The Long-term Strategy of the United States. Pathways to Net-Zero Greenhouse Gas Emissions by 2050

2.1 ELECTRICITY catalyzed through providing incentives and standards to reduce pollution from power plants; investing in Fast and cost-effective emission-reducing investments technologies to increase the flexibility of the electricity are available in the electric power sector, which is system, such as transmission, energy efficiency, currently the second-largest producer of emissions in the energy storage, smart and connected buildings, and United States. That is why the United States set a goal non-emitting fuels; and leveraging carbon capture and to reach a 100% carbon pollution-free electricity system storage (CCS) and nuclear. Significant deployment by 2035, which can be achieved through multiple cost- of energy efficiency reduces overall demand and effective technology and investment pathways. In fact, can lower peak load, reducing grid capital costs and this transition has already been accelerating in recent making investments in carbon-free power generation years—driven by plummeting costs of key technologies go further. Research, development, demonstration, like solar, onshore wind, offshore wind, and batteries, and deployment of new software and hardware as well as enhanced policies and increased consumer solutions will further support the transformation to a demand for clean, reliable, and affordable power. carbon pollution-free, resilient, reliable, and affordable Further acceleration of clean energy deployment can be electricity system. 14 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S

2.2 TRANSPORTATION 2.3 BUILDINGS Vehicles have become the largest emissions source Buildings and their energy-consuming systems— in the United States—driven by fossil fuel use in light- electricity used and fossil fuels burned on site for heating duty cars, trucks, and SUVs, followed by medium- and air, heating water, and cooking—have long lifetimes. heavy-duty trucks, buses, air, off-road vehicles, rail, Therefore, the priority in this decade is to rapidly and shipping. There are many opportunities to reduce improve energy efficiency and increase the sales share GHG emissions from transportation while also saving of clean and efficient electric appliances—including money for households and businesses, improving heat pumps for space conditioning, heat pump water environmental quality and health in communities, heaters, electric and induction stoves, and electric and providing more choices for moving people and clothes dryers—while also improving the affordability of goods. At its core, this requires electrifying most energy and the equitable access to efficient appliances, vehicles to run on ever-cleaner electricity and shifting efficiency retrofits, and clean distributed energy to low-carbon or carbon-free biofuels and hydrogen in resources in buildings. This includes investment in public applications like long-distance shipping and aviation. buildings such as public housing, government facilities, schools, and universities. Research and demonstration To support this outcome, the United States set a goal investments now will also advance new solutions for for half of all new light-duty cars sold in 2030 to be efficient, grid-interactive, and electrified buildings. zero-emission vehicles, to produce 3 billion gallons of sustainable aviation fuel by 2030, and to accelerate Achieving 100% clean power generation by 2035 will deployment and reduce costs in every mode of also eliminate upstream emissions from electricity transportation. This will occur through lower vehicle and facilitate carbon-free and efficient electrification costs; fuel economy and emissions standards in light-, of appliances and equipment in buildings. Moreover, medium- and heavy-duty vehicles; incentives for zero- partnerships like the Environmental Protection Agency emission vehicles and clean fuels; investment in a new (EPA) ENERGY STAR and the advancement of building charging infrastructure to support multi-unit dwellings, energy codes and appliance standards will ensure public charging, and long-distance travel; scaling up that building envelopes, electric appliances, and other biorefineries; comprehensive innovation investments to equipment become increasingly efficient over time. reduce hydrogen costs; and investment in infrastructure Efficient electric space heating and cooling and water that supports all modes of clean transportation—such heating offer important opportunities to employ grid- as transit, rail, biking, micro mobility, and pedestrian interactive demand to lower energy bills for households options. and businesses while more cost-effectively utilizing carbon-free electricity. Making progress this decade requires investing in domestic manufacturing and reliable supply chains for clean fuels, batteries, and vehicles. In addition, research, 2.4 INDUSTRY development, demonstration, and deployment of The industrial sector emits GHGs through multiple electrification and zero- or low-carbon fuels for aviation complex pathways. This includes CO2 emitted indirectly and shipping will ensure we have the technology through electricity and directly through on-site fossil to continue reducing emissions across the entire fuel combustion and power generation, as well as transportation sector in the years leading to 2050. emissions of CO2 and non-CO2 GHGs leaked from on- site use or emitted through industrial processes (such as cement production). Industrial decarbonization can be delivered through energy efficiency; industrial electrification; low-carbon fuels, feedstock, and energy 15 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S sources; and industrial CCS. Achieving clean power 2.5 AGRICULTURE, FORESTRY, AND LAND USE by 2035 will eliminate the emissions from grid power consumed by industry and make possible the carbon- America’s vast lands provide opportunities to both free electrification of certain industrial processes that reduce emissions and sequester carbon. Capitalizing are currently dominated by fossil fuel use. Low- and on these opportunities includes: continuing to expand medium-temperature process heat are candidates forest area, extending rotation lengths, protecting forest for industrial electrification in the near term through area, integrating trees into urban areas and agriculture, increased use of industrial heat pumps, electric boilers, scaling up climate-smart agricultural practices such as or electromagnetic heating processes. cover crops, and employing rotational grazing on our agricultural lands. Even more leverage can be derived Additional technologies and process innovations are through programs and incentives to improve agricultural also needed to address other industrial emissions, productivity; such practices and technologies can free up including high-temperature heat and process emissions land for other uses as well as reduce agricultural methane from steel, petrochemical, and cement production. and N2O emissions through, for example, improved Fundamentally new processes will be needed to address manure management and improved cropland nutrient the chemical process emissions associated with the management. Enhanced investment in forest protection production of these commodity materials that have and forest management, along with science-based and large GHG emissions footprints. Energy efficiency sustainable efforts to reduce the scope and intensity measures make carbon-free electricity and other low- of catastrophic wildfires and to restore fire-damaged carbon industrial fuels stretch as far as possible and as forest land, are vital to protecting and growing the largest early as possible. land sink. Alongside these efforts, the United States will support nature-based coastal resilience projects including The United States will also scale support for pre-disaster planning as well as efforts to increase carbon related research, development, demonstration, sequestration in waterways and oceans by pursuing commercialization, and deployment of zero-carbon “blue carbon.” Finally, climate-smart practices can industrial innovations. This includes incentives for also lower the emissions intensity of biofuels needed carbon capture and new sources of clean hydrogen— for decarbonizing transportation. Actions taken now produced from renewable energy, nuclear energy, and through this decade will ensure we maximize the or waste—to power industrial facilities. To drive potential of our lands and waters to sequester carbon to the market for these solutions, the United States the greatest extent possible by 2050. government will also use its procurement power to support early markets for these very low- and zero- Across these sectors, the U.S. federal government is carbon industrial goods. working with Tribal governments, states, and localities to support rapid deployment of new carbon-pollution- Additionally, monitoring and control technologies are free technologies and facilities while ensuring they needed to prevent the release to the atmosphere of meet robust and rigorous standards for workers, public non-CO2 GHGs from industrial operations, including and environmental safety, and environmental justice. methane, fluorinated gases, black carbon, and other Accomplishing the goals this decade and setting up the potent short-lived climate pollutants. The United economy for further reductions after 2030 also requires States has finalized regulations to phase down the use investment in innovation and U.S. manufacturing to lower of fluorinated gases consistent with our obligations the cost of new technologies needed in the future, grow under the Kigali Amendment to the Montreal Protocol. the domestic manufacturing base and supply chains for Addressing methane emissions will also require setting those technologies, and train the workforce needed. stringent standards for oil and gas production and investing in plugging leaks from coal, oil, and gas mines and wells. 16 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S CHAPTER 3: PATHWAYS TO 2050 NET-ZERO EMISSIONS IN THE UNITED STATES The decisive decade through 2030 is central to setting 3.1 ASSESSING MITIGATION OPPORTUNITIES the United States—and the world—on a pathway that TO ACHIEVE NET-ZERO EMISSIONS keeps warming of 1.5°C within reach. For all countries, 2030 is an essential waypoint that is part of a longer Achieving rapid emissions reductions requires path to reach global net-zero emissions by mid-century. integrating near-term policy drivers with a strategy The ambitious policies and goals described in Chapter to assess and manage longer-term factors like capital 2 will set the United States on a pathway to achieve stock turnover and technological innovation. To this our 2030 target. At the same time, these actions will end, this LTS employs diverse analytical approaches also catalyze the longer-term changes in the American to project the impact of alternate assumptions about energy, industrial, and land systems required to achieve policies, technologies, and other drivers. These afford net-zero by 2050. a broad understanding for what long-term net-zero technology transformations would look like globally [16] This chapter presents the results of a comprehensive as well as providing roadmaps for how to affect those analysis undertaken to assess potential pathways to transitions rapidly [17]. net-zero emissions in the United States by no later than 2050. These pathways are all grounded in our strategy In light of the Paris goals to develop and communicate to achieve our 2030 NDC and our goal of 100% carbon national emissions reductions pathways, such analytical pollution-free electricity by 2035. These transition approaches have also been applied to understanding pathways are not only affordable, but, because of the specific national circumstances and opportunities, benefits from reduced climate change and improved including those within the United States. Some of these public health, they will also create wide-ranging benefits U.S.-specific studies focus on policy frameworks to drive (see Chapter 7). It will require ambitious action and near-term action that would set the U.S. on a pathway investment grounded in intensive engagement with to longer-term net-zero or 1.5°C-compatible emissions communities, workers, and businesses to ensure that the [18] [19] [20]. In parallel, others look at the potential benefits of the transition are equitably distributed—with for integrating all-of-society strategies that include a focus on those communities that remain overburdened diverse levels of government and other actors [21]. and underserved. 17 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S Others have focused on overall long-term technological be achieved through diverse, proven approaches, transformations and associated emission reduction ranging from new and more efficient appliances and strategies that would be necessary for reduction to the integration of efficiency into new and existing net-zero in the U.S. by 2050. Many of these 2050 buildings, to sustainable alternate manufacturing studies address emissions reduction across the entire processes and the integration of efficiency into new economy and for all gases [14] [22] [23]; others focus on and existing buildings. specific areas or sectors such as energy, electricity [13] [24], transportation [25], or manufacturing [26]. This 4. REDUCE METHANE AND OTHER NON-CO2 EMISSIONS. research has advanced thinking about what is possible Non-CO2 gases such as methane, HFCs, nitrous within the United States and what robust strategies to oxide, and others contribute significantly to reach 2050 net-zero could look like. The assessment warming, with methane alone contributing fully and analytical approaches presented here are original to half of current net global warming of 1.0°C. There this report but also recognize the many insights offered are many profitable or low-cost options to reduce in this wider literature, including but not limited to non-CO2 sources, such as implementing methane studies specifically on 2050 net-zero pathways. Insights leak detection and repair for oil and gas systems from this literature are consistent in what they tell us and shifting from HFCs to climate-friendly working about the critical elements supporting the long-term fluids in cooling equipment. The U.S. is committed emissions reduction trajectory for the United States. to taking comprehensive and immediate actions to reduce methane domestically. And through the This trajectory rests on the integration of five Global Methane Pledge, the U.S. and partners seek complementary technological transformations: to reduce global methane emissions by at least 30% by 2030, which would eliminate over 0.2°C 1. DECARBONIZE ELECTRICITY. Electricity delivers of warming by 2050. The U.S. will also prioritize diverse services to all sectors of the American research and development to unlock the innovation economy. The transition to a clean electricity needed for deep emissions reductions beyond system has been accelerating in recent years— currently available technologies. driven by plummeting costs for solar and wind technologies, federal and subnational policies, 5. SCALE UP CO2 REMOVAL. In the three decades to and consumer demand. Building on this success, 2050, our emissions from energy production can the United States has set a goal of 100% clean be brought close to zero but certain emissions electricity by 2035, a crucial foundation for net-zero such as non-CO2 from agriculture will be difficult to by 2050. decarbonize completely by mid-century. Reaching net-zero emissions will therefore require removing 2. ELECTRIFY END USES AND SWITCH TO OTHER CLEAN carbon dioxide from the atmosphere, using FUELS. We can affordably and efficiently electrify processes and technologies that are rigorously most of the economy—from cars to buildings and evaluated and validated. This requires scaling up industrial processes. In areas where electrification land carbon sinks as well as engineered strategies. presents technology challenges—for instance aviation, shipping, and some industrial processes— There are many plausible pathways through 2050 to we can prioritize clean fuels like carbon-free achieving a net-zero emissions economy. However, hydrogen and sustainable biofuels. developments in these sectors over time are interdependent. For example, widespread adoption 3. CUT ENERGY WASTE. Moving to cleaner sources of in leading energy efficiency practices in buildings energy is made faster, cheaper, and easier when could significantly impact overall electricity demand, existing and new technologies use less energy reducing the amount of new clean energy installations to provide the same or better service. This can 18 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S required. The insight that sectors are interdependent 3.3. ANALYSIS OF POTENTIAL U.S. demonstrates the importance of policy and incentives TRAJECTORIES TO NET-ZERO EMISSIONS to realize the benefits of decarbonization across BY 2050 the economy. Recent developments in energy, manufacturing, and information technology have The new analysis presented here offers insights into made swift and substantial reductions possible. what the overall emissions profile for the United Well-designed policies can help to ensure rapid and States could look like between now and 2050 under affordable economy-wide decarbonization. For example, a set of alternate assumptions about the evolution accelerated shifting to carbon-free power makes end- of technological costs, economic growth, and other use electrification an even more effective strategy drivers to 2050. We use two economy-wide models to drive down emissions. In addition, policies can (GCAM and OP-NEMS), a range of sensitivity scenarios, maximize the benefits of decarbonization and ensure supplemental models for key sectors, and comparisons that underserved communities benefit equitably from to the growing literature on pathways to net-zero the transition to a clean energy system. For example, emissions. This provides transparency on what the inclusive investment programs to scale up financing possible pathways to 2050 net-zero might look like, and for efficient electric home upgrades can help level the how those different pathways would affect the evolution playing field for underserved households and ensure of specific sectors and rates of deployment for specific effective consumer protections. technologies. The assessment presented in this chapter reflects model

3.2 CURRENT U.S. GHG EMISSIONS TRENDS outputs that are subject to several types of uncertainty. IN 2021 The goal of showing these outputs is to illustrate the evolution of the U.S. economy and resulting emissions Net U.S. GHG emissions peaked in 2007 [27] after over time. While the technology assumptions and growing through much of the previous century, driven policy goals for the decade to 2030 are largely mainly by combustion of fossil fuels to meet growing understood, there is increasing uncertainty after 2030 demand for energy services. Since their peak, net U.S. on how any individual technology or sector will evolve. GHG emissions have declined, driven by a combination We show several different pathways based on alternate of forces. Federal policy has played a crucial role, assumptions. These sensitivities illustrate a range of including through sustained research and development credible and plausible pathways to net-zero by 2050. investments which propelled an initial shift from coal to gas power and the simultaneous and now dominant growth of renewables; incentives for renewables and 3.3.1 DESCRIPTIONS OF THE MODELS zero-emission vehicles; and sector-specific regulations such as emissions standards for power plants, fuel Global Change Assessment Model (GCAM) economy standards, and appliance efficiency standards. Tribal governments, U.S. states, cities, counties, and The LTS scenarios were produced in the Global Change other non-federal actors have played a similarly crucial Analysis Model (GCAM) by the Pacific Northwest role across all sectors of the economy. Moreover, National Laboratory. The Global Change Analysis this federal and subnational investment and policy Model (GCAM) is an integrated assessment model has propelled a virtuous cycle of technology cost covering all major GHGs and all sectors of the economy, reductions inducing even larger markets for key carbon- linking the world's energy, agriculture, and land use free technologies which, in turn, drives further cost systems with a climate model. It is used to explore reductions through scale and learning. the interactions of emissions-reducing investments and activities across the U.S. and global economy. The model is designed to assess climate change policies and 19 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S technology strategies for the globe over long time scales. Global Timber Model (GTM) GCAM runs in 5-year time steps from 2005 to 2100 and includes 32 geopolitical regions in the energy and The Global Timber Model (GTM) is a dynamic economy module and 384 land regions in the agriculture intertemporal optimization economic model that and land use module. The model tracks emissions and determines timber harvests, timber investments, and atmospheric concentrations of GHGs (CO2 and non- land use optimally over time under assumed future CO2), carbonaceous aerosols, sulfur dioxide, and reactive market, policy, and environmental conditions. This gases and provides estimates of the associated climate model’s approach provides a simulation of harvesting, impacts, such as global mean temperature rise and sea planting, and management intensity decisions that level rise. GCAM can incorporate emissions pricing and landowners might undertake in response to timber emission constraints in conjunction with the numerous and carbon market demands, including future price technology options including solar, wind, nuclear, and expectations. These activities include afforestation carbon capture and sequestration. The model has and land use change, forest management, and forest been exercised extensively to explore the effect of products activity in response to policies and markets. technology and policy on climate change and the cost The model generates projections using detailed of mitigating climate change. GCAM is a community biophysical and economic forestry data for different model primarily developed and maintained at the Joint countries or regions globally, including the U.S., China, Global Change Research Institute, a partnership between Canada, Russia, and Japan. It used macroeconomic Pacific Northwest National Laboratory (PNNL) and the data from Annual Energy Outlook 2021 for the U.S. University of Maryland [28]. and global parameters from Shared Socioeconomic Pathway 2 (SSP2) [30]. The model has been widely used to assess forest dynamics and carbon outcomes under Office of Policy – National Energy Modeling System various demand and land carbon sink scenarios, climate (OP-NEMS) impacts, and other applications [31] [32]. The LTS scenarios were constructed using a version of the National Energy Modeling System (NEMS) Forestry and Agriculture Sector Optimization Model developed by the U.S. Department of Energy (DOE) with Greenhouse Gases (FASOM-GHG) Office of Policy (OP-NEMS). NEMS is an integrated energy-economy modeling system for the United States The Forestry and Agriculture Sector Optimization that projects the production, imports, conversion, and Model with Greenhouse Gases (FASOM-GHG) model consumption of energy, subject to assumptions on is a partial-equilibrium dynamic intertemporal, price- macroeconomic and financial factors, world energy endogenous, mathematical programming model markets, resource availability and costs, cost and depicting land transfers and other resource allocations performance characteristics of energy technologies, between and within the agricultural and forest sectors and demographics. The version of NEMS used in this in the United States. FASOM-GHG includes detailed report has been run by OnLocation, Inc., with modeling representations of agricultural and forest product approach determined with input from the DOE Office markets, contemporary forest inventories, intersectoral of Policy and other DOE technology offices. Because resource competition and land change costs, and costs OP-NEMS projects only CO2 emissions related to the of mitigation strategies. The results from FASOM- energy sector, external assumptions were provided GHG yield a dynamic simulation of prices, production, regarding non-CO2 GHGs and land use, land-use change, management, consumption, GHG effects, and other and forestry. OP-NEMS includes enhancements for clean environmental and economic indicators within these hydrogen, sustainable biofuels, and industrial carbon two sectors, under the chosen policy scenario. The capture, transport, and storage [29]. result provides insight into cross-sectoral inter- and intra-regional responses to policy stimuli reflecting 20 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S the spatial heterogeneity in production of agriculture (i.e., carbon dioxide removal, sector-specific and forestry products across the U.S. To date, FASOM- technologies, and non-CO2 mitigation technologies), GHG and its predecessor models have been used to energy prices, population, and economic growth. examine the effects of GHG mitigation policy, climate The advanced LTS scenario assumptions account for change impacts, public timber harvest policy, federal currently available opportunities as we build back from farm program policy, bioenergy prospects, and pulpwood the pandemic by using advanced assumptions for production by agriculture among other policies and electricity, transportation, industry, and buildings as environmental changes [33]. modeled in GCAM and OP-NEMS. The underlying assumptions in the scenario sets are U.S. Department of Agriculture Forest Service as follows. Carbon removal levels represent the sum of Resources Planning Act (RPA) modeling system the net land sink, derived from modeled projections of The LTS scenarios reflect results from the U.S. Department land use, land use change, and forestry (LULUCF), and of Agriculture (USDA) Forest Service Resources Planning plausible levels of carbon dioxide removal technology Act (RPA) modeling system which comprises the Forest adoption such as biomass energy with CCS and direct Dynamics model, integrated and harmonized with the air capture from the literature [37] [38]. The combined USDA Forest Service RPA Land Use Change Model and carbon removals from these sources are roughly 1,000, the Forest Resource Outlook Model (FOROM) Global 1,400, and 1,800 MtCO2 per year in 2050 over the Trade Model [34]. This modeling system supports the low, medium, and advanced cases, respectively. The projections of renewable resources across the U.S. in advanced and lower technology assumptions for the the USDA 2020 Resources Planning Act Assessment. electricity and transportation sectors rely largely upon Projections were developed under current climate the National Renewable Energy Laboratory’s Annual conditions without CO2 fertilization and values are added Technology Baseline. The advanced assumptions to USDA agriculture soils projections. The storage and for the buildings and industrial sectors draw on the flux of carbon in harvested wood products and solid waste existing literature and programmatic goals for the disposal sites was projected using FOROM. advanced cases and slower improvements in the lower cases, which are more aligned with standard model parameters. For non-CO2 reductions, the advanced U.S. EPA Non-CO2 Marginal Abatement Cost (MAC) technology assumptions accelerate the availability of Model and Report low-cost technologies but do not alter long-term costs. The U.S. EPA Non-CO2 Marginal Abatement Cost (MAC) Oil and natural gas prices are calibrated to the 2021 Model is a bottom-up engineering cost model that EIA Annual Energy Outlook’s oil and gas supply cases evaluates the cost and abatement potential of non-CO2 in the reference scenario, i.e., without a net-zero 2050 mitigation technologies [35]. The associated non-CO2 target. Population and GDP, the final set of assumptions, mitigation report [36] provides a comprehensive economic span compound annual growth rates from 2020 to analysis on the costs of technologies to reduce non-CO2 2050 of 0.5% to 0.7% for population and 1.1% to 1.8% gases and the potential to reduce them by sector. for GDP. Also, the LULUCF modeling effort included the use of 5 different models to generate business as usual and potential mitigation outcomes from different

3.3.2 SCENARIO DESCRIPTIONS land-based activities, including afforestation, improved & KEY ASSUMPTIONS forest management, harvested wood products storage, The LTS analysis includes multiple scenarios highlighting and fire reduction techniques. This exercise included different pathways for achieving net-zero GHG emissions alignment of several key inputs and parameters, by 2050. The figures in this chapter present results for a including use of input data from the Forest Inventory range of assumptions including the land sink, technologies and Analysis database and, in some cases, application 21 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S Table for LTS Technology Assumptions by Sector Model(s) Used LTS Scenario Carbon Electricity Transportation Industry Buildings Non-CO2 GCAM OP-NEMS Removal Balanced Advanced Medium Advanced Advanced Advanced Advanced Advanced x Lower Non-CO2 Medium Advanced Advanced Advanced Advanced Lower x Lower Buildings Medium Advanced Advanced Advanced Lower Advanced x Lower Industry Medium Advanced Advanced Lower Advanced Advanced x Lower Medium Advanced Lower Advanced Advanced Advanced x Transportation Lower Electricity Medium Lower Advanced Advanced Advanced Advanced x Lower Removals Lower Advanced Advanced Advanced Advanced Advanced x x Higher Removals / Higher Advanced Lower Lower Lower Lower x x Lower Technology High Oil & Gas Price Medium Advanced Advanced Advanced Advanced Advanced x Low Oil & Gas Price Medium Advanced Advanced Advanced Advanced Advanced x High Population & Medium Advanced Advanced Advanced Advanced Advanced x GDP Low Population & Medium Advanced Advanced Advanced Advanced Advanced x GDP Table 1: Long-Term Strategy Scenarios. To explore multiple ways to reach our net-zero emissions goal in 2050, this analysis includes twelve scenarios (shown in the left most column of the table). The ‘Balanced Advanced’ scenario includes medium levels of carbon removals from the atmosphere through our land use, land use change, and forestry (LULUCF) sink and carbon dioxide removal (CDR) technologies, and advanced technology assumptions allowing for a balanced approach across sectors. The next six scenarios explore lower technology assumptions for electricity, transportation, industry, buildings, non-CO2, and carbon removals, respectively. Next is a scenario that includes higher levels of carbon removals combined with lower technology assumptions for multiple sectors. The last four scenarios explore high and low oil and gas price sensitivities, and high and low population and GDP growth projections. of Shared Socioeconomic Pathway (SSP) 2 information As described above, this reduction can result from for macroeconomic drivers. The land use models applied combinations of five major categories of action: energy in this analysis did not incorporate assumptions of efficiency; decarbonizing electricity; fuel switching and demand of CCS or bioenergy as mitigation options, as energy transitions; sequestering carbon through forests, these modeling aspects were accommodated in GCAM soils, and CO2 removal technologies; and reducing and OP-NEMS. non-CO2 emissions. Figure 3 presents a vision for how such categories of action can combine to reach net-

3.4 ECONOMY-WIDE PATHWAYS TO 2050 zero. This figure shows a representative pathway from 2005 net emissions levels through 2050 in the form of NET-ZERO EMISSIONS a waterfall chart (the left-hand side of the figure). This Achieving the 2050 net-zero goal will require reducing representative pathway provides a rough approximation net U.S. emissions from roughly 6.6 Gt CO2e in 2005 for reaching net-zero emissions using contributions (and 5.7 Gt CO2e in 2020), to zero by no later than 2050. from all sectors. 22 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S The right-hand side of the figure shows seven additional Several broad lessons from this figure are clear. First, scenarios from our analysis that are based on different in the absence of additional policies, emissions would assumptions about how technologies and policies will remain largely flat moving forward. Results in the figure evolve over time. This includes a “balanced advanced” show reductions from a baseline scenario to 2050— scenario with high levels of action across all sectors, as that means that only reductions beyond the baseline well as scenarios where one of the sectors (buildings, scenario are reflected in the colored bars. Achieving net- industry, transportation, electricity, non-CO2, land sink) zero emissions will require actions that go far beyond contributes a lower level of reductions. These alternate business as usual. scenarios serve to illustrate how the balance across technologies and policy strategies could vary while still Second, roughly 4.5 Gt of the 6.5 Gt annual reduction reaching the net-zero 2050 goal. from 2005 levels will likely come from transforming the energy system. This starts with decarbonizing REPRESENTATIVE PATHWAY TO 2050 NET-ZERO ALTERNATE PATHWAYS TO 2050 NET-ZERO Figure 3: Emissions Reductions Pathways to Achieve 2050 Net-Zero in the United States. Achieving net-zero across the entire U.S. economy requires contributions from all sectors, including: efficiency, clean power, and electrification; reducing methane and other non-CO2 gases; and enhancing natural and technological CO2 removal. The left side of the figure shows a representative pathway with high levels of action across all sectors to achieve net-zero by 2050. The right side shows a set of alternative pathways depending on variations in uncertain factors such as trends in relative technology costs and the strength of the land sector carbon sink. 23 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S electricity by shifting to renewables and other over 30 countries representing about 30% of global emissions-free power. This shift could lead to over emissions and 60% of the global economy had joined 1 Gt of annual reduction by 2050. A second pillar of the Pledge (See Box in Chapter 5). As detailed in the energy transformation is simply to use energy more NCS, the United States is implementing comprehensive efficiently to provide the same services. Solutions actions to drive down methane in this decade, including like better insulation, advanced heat pumps for new standards for landfills and oil and gas operations space and water heating, and efficient computers as well as major investments to remediate abandoned and electronics can save consumers billions on their coal, oil, and gas mines and wells. The United States is annual energy bills. Cutting energy waste also reduces also committed to incentives and innovations to reduce the rate of investment needed for new clean energy agricultural methane and agricultural N2O emissions. generation as demand grows. This pillar alone could Finally, a global HFC phasedown is expected to avoid up contribute roughly 1 Gt of annual reductions by 2050. to 0.5°C of global warming by 2100. A third pillar of energy transformation is to switch as many uses as possible to clean energy—including Fourth, removing CO2 from the atmosphere is a clean electricity, but also including low-carbon necessary component for reaching net-zero. Although fuels and clean hydrogen. Efficient electrification of most emissions across the economy can be eliminated transportation, buildings, and other end uses can also through the above strategies, a few processes or transform the energy sector by reducing overall energy activities that lead to emissions are currently difficult demand. Electric motors in vehicles, for example, are or costly to eliminate or have no viable existing approximately three times more efficient than internal substitutes, and despite many available cost-effective combustion engines, and electric heat pumps are up mitigation opportunities, non-CO2 GHG emissions to three times more efficient than heating with natural cannot be fully reduced to zero. This means that gas or electric resistance. These activities would lead reaching net-zero will require additional contributions to nearly 2 Gt of annual reductions by 2050. from removals until viable zero-emission solutions are developed and deployed. Overall, these removals Third, other non-CO2 GHG emissions represent a would come from two broad categories of activities. critical component of the overall reduction strategy, One is through nature-based approaches that rely on collectively representing roughly 0.5 Gt of reductions natural carbon sinks—land and ocean—by expanding by 2050. These gases have sources across many or enhancing conservation, restoration, sustainable sectors and include methane emissions from management and other activities that would enhance agriculture, waste management, and fossil fuel use, natural removal of carbon as well as protect our HFCs used in refrigeration, and N2O from agriculture vital natural ecosystems and related services and and industry. Such gases often offer low cost and high biodiversity. A second set of approaches is through impact reductions. For example, globally, methane various technologies and processes that directly accounts for half of the net 1.0°C of warming already capture CO2 from the atmosphere and store it (such occurring. Because of its relatively short lifetime in as direct air or ocean capture, bioenergy with CCS, the atmosphere, compared to CO2, rapidly reducing or enhanced mineralization). Technologies capable methane emissions is the single most effective strategy of carbon dioxide removal are available today, but at to reduce warming over the next 30 years and is nascent stages and therefore will require additional crucial in keeping to the 1.5°C limit. The United States research, development, and deployment now through co-leads with the EU the Global Methane Pledge that 2050 (more discussion of CDR technologies can be aims to eliminate over 0.2°C of potential warming by found in section 6.4). 2050 by cutting global methane pollution at least 30% by 2030 relative to 2020 levels. As of October 2021, 24 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S CHAPTER 4: TRANSFORMING THE ENERGY SYSTEM THROUGH 2050 The energy sector is pivotal for achieving net-zero emissions by 2050. Achieving net-zero is possible through a range of pathways, which depend on how technologies and policies evolve over the three-decade period. Nevertheless, by modelling a range of pathways with plausible assumptions for this evolution (see Figure 4), we Transportation can distinguish broad trends and Buildings important drivers of the energy sector 2.0 Industry Energy Emissions (Gigatons CO2) transformation. Electricity CDR 1.0 Figure 4: U.S. Energy CO2 Emissions to 2050 by Economic Sector. Electricity CO2 emissions and direct CO2 emissions from the transportation, buildings, and industry fall dramatically in all scenarios, with the greatest reductions coming from electricity, followed 0.0 by transportation, and non-land sink carbon dioxide removals (CDR) increase. Notes: Historical data are from EIA Monthly Energy Reviews, projections include data from all LTS scenarios using both GCAM and OP-NEMS, 2005 2020 2050 projections are shown in ten-year time steps. 25 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S

4.1 ELECTRICITY by increases in renewables and decreases in coal-fired generation (see Figure 5). Continued cost reductions The United States has set a goal for 100% carbon in generation and storage are expected to enable even pollution-free electricity by 2035, and this goal will more rapid reductions of emissions from this sector. provide an important foundation for the Long-Term New policies, incentives, market reforms, and other Strategy of the United States. Electricity is used in actions will be needed to ensure that electricity sector every economic sector, and all 2050 net-zero pathways emissions continue to decrease as total electricity depend on rapidly decarbonizing electricity and demand increases. expanding the use of this decarbonized electricity into as many uses as possible to displace polluting fuels. The electricity sector will continue to evolve rapidly as The electricity sector, which contributes about a quarter it decarbonizes. Expected continued cost reductions of all U.S. GHG emissions, has been reducing CO2 in renewable generation as well as battery and other emissions for years, with major shifts caused in part storage technologies could see emissions decreases of Fossil w/ CCS Fossil w/o CCS Electricity Generation (Trillion kWh)

6.0 Nuclear Renewables Non-Fossil Combustion Biomass w/ CCS 4.0 2.0 0.0 2005 2020 2050 Figure 5: U.S. Electricity Generation 2005-2050. Generation by source in trillion kilowatt-hours. Total generation expands to 2050 due to increased use of clean electricity in new applications in transportation, industry, and buildings. Renewable generation increases rapidly to keep pace with growing electricity demand and ensure that the share of renewables continues to expand to 2050. Note: Historical data are from EIA Monthly Energy Reviews, projections include data from all LTS scenarios using both GCAM and OP-NEMS, projections are shown in ten-year time steps. 26 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S roughly 70-90% by 2030 on a path toward the 2035 changing supply and demand over all increments of 100% clean electricity goal. As shown in Figure 5, solar time. In particular, longer-duration storage solutions and wind generation continues to increase substantially and appropriate incentive mechanisms will be critical. through 2050, while existing nuclear generation Absent new action, supply chains may become stressed remains in operation and could see growth in the by limited availability of raw materials (such as rare 2030s and 2040s. Unabated fossil generation (coal earth elements), manufacturing capacity, and skilled or gas generation without CCS technology) declines, workforce. Some pathways may also require significant and existing fossil fueled plants start to be fitted with expansion of carbon capture and storage technologies carbon capture. By 2050, clean generation provides during the overall transition, which bring specific zero emission electricity to the rest of the economy, challenges around technology development and siting. with all electricity providing 15-42% of primary energy. These challenges are substantial but can be addressed Recent analyses suggest that wholesale electricity through an integrated strategy of investment, prices, on average, are unlikely to change significantly innovation, and new technology deployment. Large- as we shift to a cleaner grid by 2030, with price impact scale deployment of renewables can be accelerated estimates ranging from a 4% decrease to a 3% increase by investments in grid infrastructure and advanced [39]. Additionally, the transition to clean electricity is technologies. Grid infrastructure investments, expected to reduce exposure of U.S. consumers to fuel including the buildout of new long-distance, high- supply shocks [40]. voltage transmission projects, can enhance resilience, improve reliability, better integrate variable generation Investment in clean energy generation must continue resources, lower electricity costs, and unlock the best through mid-century as overall electricity generation clean energy resources by connecting them to demand increases to meet demand growth from other sectors. centers. Significant deployment of energy efficiency Average annual total capacity additions without storage can also help reduce the scale of investment required from 2021 to 2030 range from 58 gigawatts per year by lowering the total energy demand that must be met. (GW/yr.) to 115 GW/yr.; in 2031 to 2040 they range Analyses show that as the sector becomes increasingly from 54 GW/yr. to 167 GW/yr.; and in 2041 to 2050 decarbonized, advanced technologies will be brought they range from 67 GW/yr. to 123 GW/yr. Storage online to meet peak load and adjust to seasonal capacity additions from 2021 to 2030 average 0.4 GW/ changes in demand. Advanced technologies—which yr. to 2.7 GW/yr.; in 2031 to 2040, they range from 3 could include clean hydrogen combustion or fuel cells, GW/yr. to 40 GW/yr.; and in 2041 to 2050 they range enhanced geothermal systems, long-duration energy from 11 GW/yr. to 64 GW/yr. storage, advanced nuclear, and fossil generation This rapid evolution and scale of change in the with CCS—can provide clean firm resources that can electricity sector is ambitious, with high and sustained balance increased variable generation. However, these deployment of new technologies through mid-century. technologies require a rapid, sustained acceleration Many significant challenges and barriers exist [14] [22]. in research, development, and deployment. The The electricity transition will require adding significant significant investments in generation and transmission amounts of new zero-carbon electricity capacity at a will underpin job growth across the nation, creating sufficient pace to replace uncontrolled fossil fuel-fired opportunities in cities and rural areas alike, particularly generation while also providing ample clean supply for when paired with workforce training. Expansion a growing economy with increased electrification. New of the transmission system, stronger interregional transmission, distribution, and storage infrastructure coordination, and distributed generation also provide will be needed to maintain and improve grid reliability, resilience to natural disasters, saving lives and including adapting the electric grid to be flexible to protecting businesses. 27 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S RAPID DECARBONIZATION IN THE U.S. ELECTRICITY SECTOR IS UNDERWAY The electricity sector in the United States has been decarbonizing rapidly, with significant increases in renewable deployment in recent years. The shift to lower-emissions sources has been under way for decades, with early contributions from nuclear and then fossil gas. More recently, since around 2010, federal investment policies, tax credits, and regulatory actions, as well as state policies, research and development, and market trends, drove significant renewable deployment. At the same time, between 2010 and 2019, more than 546 coal-fired power units retired, totaling 102 GW of capacity, with another 17 GW of capacity planned for retirement by 2025 [41]. This has led to a dramatic shift in the sources of U.S. electricity, with renewables now accounting for more generation than coal (Figure 6). In addition, the sum of coal and natural gas generation has also declined in the last decade, pointing to the important role of renewable energy. One of the challenges to reach the 2050 net-zero goal (as well as the 2035 100% clean electricity goal) is the large amount of new zero-emission capacity (primarily renewables) that will need to be deployed annually to enable an increasingly large share of clean electricity generation. Figure 7 shows some indicative estimates of the magnitude of the annual capacity additions needed to remain on pace toward our goals, in comparison to recent historical levels of capacity additions. Recent trends in renewable deployment are encouraging. Solar and wind capacity additions were about 32 GW in 2020, the highest on record, and are expected to be about 28 GW in 2021. Acceleration will be needed but the deployment rate has been growing quickly. 28 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S 2.0 Source (percentage of Electricity Generation (Trillion kWh) 2020 total)

1.5 Natural Gas (40%) 1.0 Renewables (21%) Nuclear (20%) Coal (19%) 0.5

0.0 Other (<1%) 1950 1960 1970 1980 1990 2000 2010 2020 Figure 6: Annual U.S. Electricity Generation from All Sectors 1950-2020 (trillion kilowatt-hours). The electricity sector has been rapidly decarbonizing since 2008. This figure shows electricity net generation in all sectors (electric power, industrial, commercial, and residential) and includes both utility-scale and small-scale solar. Rapid increases in solar, wind, and other renewable generation means that in 2020, for the first time, renewable generation surpassed coal generation. Coal generation has declined rapidly, replaced by natural gas and renewables. Source: EIA [42]. HISTORICAL CAPACITY ADDITIONS REPRESENTATIVE PATHWAY TO 2050 NET- ZERO ALTERNATE PATHWAYS TO 2050 NET- ZERO 80 80 70 70 New Installed Capacity (Gigawatts per year) New Installed Capacity (Gigawatts per year) Other 60 Nuclear 60 Solar 50 Wind 50 0. 05Fossil w/ CCS 80 70 60 50 40 30 20 Fossil w/o CCS 1 0 40 40 30 30 20 20 10 10 0 0 2000 2010 2020 2021-2030 2031-2040 2041-2050 2021-2050 Average Figure 7: Electric Generation Capacity Additions 2000-2050. Renewable capacity additions have been growing rapidly in the past decade (left) and are more closely approaching levels that will be needed to sustain the overall decarbonization trend in electricity needed to reach the 2050 goal. A representative pathway (center) shows deployment of total zero- carbon technologies roughly on the order of 60–70 GW per year. Diverse scenarios in this analysis show a range of potential pathways to achieve net zero (right). Note: Historical data are from EIA Monthly Energy Reviews, projections include data from all LTS scenarios using GCAM. Other scenarios not shown in the figure have cumulative nuclear capacity additions ranging up to 90–100 GW through 2050. 29 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S

4.2 TRANSPORTATION The United States will continue to increase the use of electricity and sustainably produced low-carbon The transportation sector provides vital mobility fuels in the transportation sector while shifting away services for people and goods with on-road vehicles, from fossil sources (Figure 8). Over time, electricity, planes, trains, ships, public transportation, and a wide carbon beneficial biofuels, and hydrogen will become variety of other modes. It is currently the highest increasingly clean. The availability and adoption of emitting sector, representing 29% of all U.S. emissions these low-carbon fuels in the coming decades will [27]. To reduce emissions to net-zero by 2050 we will largely depend on the economics of production and/ need to ensure that zero-emission vehicles dominate or procurement, the competitiveness of bioenergy new sales for most types of vehicles by the early 2030s, and hydrogen compared to alternative low-carbon as well as infrastructure to support alternate modes of technologies across sectors, policy support, private transportation, such as trains, bikes, and public transit. 30 Alternative Fuels Electricity Fossil Transportation Energy (Exajoules) 20 Figure 8: U.S. Transportation Final Energy Use 2005-2050. Overall transportation energy in exajoules (EJ) decreases while the use of electricity and alternative fuels, including biomass-derived fuels and hydrogen, increases to power nearly the full U.S. transport system by 2050. While light-duty vehicles are almost all electric by 2050 in most scenarios, there 10 is uncertainty in other transportation sectors. Uncertainties in the future share of low-carbon bioenergy vs. hydrogen makes can affect the potential for electrification in the sector. These results show end use consumption instead of service demand (e.g., per mile travelled), so electricity demand appears smaller than alternative fuels demand due to the major inherent efficiency advantages of electric vehicles. Note: Historical data are from EIA 0 Monthly Energy Reviews, projections include data from all LTS scenarios using both GCAM and OP-NEMS, projections are shown in ten-year 2005 2020 2050 time steps. 30 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S investment and, in the case of bio-based energy, the An integrated strategy to address these substantial ability to minimize potential negative land carbon challenges can help accelerate the development and outcomes and other environmental impacts of biomass rapid expansion of new transportation technologies. production. Although demand for transportation An expanded network of public transit options and services increases through mid-century, the total infrastructure will increase urban mobility, helping energy consumed in this sector declines due to a to reduce emissions and increase equity in mobility. combination of regulations and technological advances Electrifying segments of the rail system will decarbonize which drive efficiency improvements and deliver the existing rail system with the added benefit of societal and consumer benefits. enabling a more robust electric grid along railroad “right of way.” Additionally, “vehicle to grid” innovations may A central component of the U.S. Long-Term Strategy provide support for grid services. Accelerated research, in transportation is the expanded use of new development, demonstration, and deployment of lower- transportation technologies—including a rapid carbon fuels, such as clean hydrogen and sustainable expansion of zero-emission vehicles—in as many biofuels, will contribute to the decarbonization of applications as possible across light-, medium-, applications that may be more difficult to electrify and heavy-duty applications. Already, the growing including aviation and marine transportation and some popularity of electric vehicles (EVs), supported medium- and heavy-duty trucking segments. by incentives and continued advances in battery technology, is spurring greater EV adoption and industry goals for even higher EV sales. Other 4.3 BUILDINGS technologies can serve as important complements Buildings house our population and provide a working to EVs. The President’s goal and associated policies environment for commercial sectors including offices, to ensure half of all new vehicles sold in 2030 zero- colleges and K-12 schools, restaurants, grocery stores, emissions vehicles (including battery electric, plug- and retail shops. Homes and commercial buildings in hybrid electric, or fuel cell electric vehicles) will are responsible for over one-third of CO2 emissions continue to spur growth across all zero-emission vehicle from the U.S. energy system. Of this, roughly two- types. thirds of buildings sector emissions currently come This rapid deployment of zero-emissions vehicles from electricity, with the remainder coming from is ambitious and will need to occur at a large scale direct combustion of gas, oil, and other fuels for space across all vehicle types. Many challenges and barriers heating, water heating, cooking, and other services, and exist [14] [22] [25]. For example, costs for electric buildings currently account for about three quarters of technologies, fueling, and charging infrastructure U.S. electricity sales [43]. Electricity is used in buildings remain high in some applications. Some transportation for lighting, space heating and cooling, water heating, segments, such as aviation, will likely remain difficult to electronics and appliances, and other services. CO2 electrify and some legacy vehicles will continue to be emissions from buildings have been falling since 2005, necessary in the near term, both of which would require due to increases in energy efficiency, the decarbonization alternate sources of low-carbon fuels that have yet to of the electricity sector, and a modest trend towards the be deployed at the necessary scale. The existing built electrification of end uses. These emissions reductions environment creates also high dependency on owner- have been achieved even as commercial building occupied vehicles and presents numerous obstacles to square footage has increased by more than 25% and alternate mobility options and shifting between modes the population has grown by more than 10% since such as transit, biking, or walking. 2005. All buildings need to be decarbonized with an emphasis on strategies that deliver for overburdened and underserved communities. For example, in the residential sector, households with an annual income below 31 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S $60,000 account for nearly 50% of all household electrification. Heat pumps and other electric heaters energy consumption, making it essential that efforts to and electric cooking account for more than 60% of decarbonize buildings are accessible to all households sales by 2030 and nearly 100% of sales by 2050. [44]. Energy demand in buildings is reduced by 9% in 2030 and 30% in 2050. The key driver of reducing building emissions is efficient use of electricity for end uses (such as While recent trends are encouraging, the building heating, hot water, cooking, and others). Alongside sector presents some unique challenges to rapid the decarbonization of electricity, these changes can decarbonization. Foremost is the often-long lifetime bring building sector emissions to near-zero by 2050. of buildings. Many buildings built today will still be in Across multiple possible pathways, building efficiency active use by 2050, which means that even immediate improvements also reduce the overall demand for actions to improve new buildings take years before energy by the sector, despite the substantial growth making a significant impact in the overall building stock. in the number of buildings, floorspace, and population These factors affect all aspects of buildings including expected through 2050 (Figure 9). Within this overall the outer shell; heating, ventilation, and air conditioning decrease in energy demand, the share of electricity in systems; and appliances and lighting—although some final energy demand grows as end uses are electrified, of these are more amenable to retrofitting than others. from about 50% in 2020 to 90% or more by 2050 In addition, energy efficiency and efficient electrification because the on-site combustion of gas, oil, and other have barriers relating to their upfront cost structure, fuels decreases substantially; however, the growth is financing, competing landlord and tenant incentives. also limited through energy efficiency and efficient These issues can be particularly difficult in underserved 15 Electricity Buildings Energy (Exajoules) 10 5 Figure 9: U.S. Buildings Site Energy 2005- 2050. Overall building site energy use in Fossil exajoules (EJ) decreases at the same time as certain applications (e.g., heating) switch from fossil fuels (and some biomass) to clean 0 electricity. Note: Historical data are from EIA Monthly Energy Reviews, projections include data from all LTS scenarios using both GCAM 2005 2020 2050 and OP-NEMS. 32 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S communities, which will also need widespread access to conditions, improving health and safety. The role of state retrofits and new building technologies, though innovative utility regulators will be especially important, as approval financing tools such as inclusive investment programs can of new rate structures and consumer incentive programs deliver substantial benefits to these communities while will be vital in realizing the full potential of consumer reducing or eliminating financing barriers and ensuring benefits. Finally, building improvements will come from consumer protections. manufacturing, construction, and installation performed by skilled, well-paid American workers in communities To address these challenges, pursuing multiple options across the country. effectively help achieve the necessary rapid emissions reductions in buildings while also reducing the energy cost burden for families and businesses and improving 4.4. INDUSTRY the health and resilience of communities. There are three The U.S. industrial sector, currently produces roughly important sources of emissions reductions: technological 23% of U.S. GHG emissions and 30% of emissions advances including from envelope improvements (e.g., from the energy system [45]. It is heterogeneous, attic and wall insulation, sealing leaks, and efficient producing a wide range of products with diverse and windows), improved efficiency of electric end uses (e.g., sometimes specialized processes. The energy-intensive lighting, refrigeration, appliances, and electronics), and and emissions-intensive industries include mining, the efficient electrification of space and water heating, steel manufacturing, cement production, and chemical cooking, and clothes drying in both existing and new production, and collectively produce nearly half of overall buildings. The rapid deployment of heat pumps for industrial emissions. In addition to the CO2 emissions space heating and cooling and water heating is the resulting from industrial demand for electricity, the central strategy for the efficient, flexible electrification industrial sector emits GHGs directly from many of buildings. By increasing the amount of demand- operations and processes including the use of fossil fuels responsive heating, cooling, and water heating on the grid, for onsite energy use and as feedstocks, direct process these technologies can respond to shifts in renewable emissions of CO2 from cement production and other generation levels on short notice and reduce the overall industries, and emission of non-CO2 GHGs such as N2O cost of a low- or zero-carbon generation mix. from nitric and adipic acid production. Efficient and electrified buildings provide substantial Although there are many hard-to-decarbonize elements consumer benefits. The most important benefit is reduced of industrial activities, investments in technologies utility bills for households and businesses which are for advanced non-carbon fuels, energy efficiency, and both direct (through lower energy usage) and indirect electrification can reduce overall industrial sector (through lower energy prices). More efficient buildings CO2 emissions by 69-95% by 2050. A large range of significantly reduces electricity demand and lessen winter potential pathways for the industrial sector are shown peaking loads as the sector electrifies, reducing the cost in Figure 10. Overall energy use drops in most scenarios of new generation, transmission, and distribution, which through energy efficiency and materials efficiency in turn reduces energy prices for American families and investments. In these scenarios, overall electricity use businesses. These bill savings would be most beneficial to in the sector grows only slightly due to electrification. low-income households, which typically face the greatest However, in scenarios that rely on a large quantity energy burden. Buildings can also support electric vehicle of hydrogen, electricity use increases dramatically charging infrastructure and rooftop solar installations, to produce the hydrogen through electrolysis. In all key elements of the broader energy transition. More scenarios, low-carbon fuels (including electricity) grow efficient buildings also retain indoor temperature for as a percentage of total energy use. longer during power outages under extreme weather 33 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S Figure 10: Industry Final Energy Use 2005-2050. Overall industrial energy use in exajoules (EJ) decreases to 2050 while certain applications switch from fossil fuels to clean electricity, hydrogen, or biofuels. Electricity use increases further in scenarios with larger hydrogen 20 production due to the high electricity demand for that pro-cess. In this analysis, CCS in deployed in industry for process emissions, but there is limited representation of CCS on industrial energy in the models we use. Accordingly, it is likely that a Industry Energy (Exajoules) greater share of industrial fossil energy emissions 15 could be captured by 2050 than is shown here. Fossil w/o CCS Note: Historical data are from EIA Monthly Energy Reviews, projections include data from all Fossil w/ CCS LTS scenarios using both GCAM and OP-NEMS, Electricity projections are shown in ten-year time steps. Biomass w/o CCS 10 Biomass w/ CCS Hydrogen 5 0 2005 2020 2050 Reducing energy-related GHG emissions from industry the specific needs of each subsector. Key strategies include presents a set of unique challenges [14] [22] [26]. A energy efficiency, material efficiency, electrification, primary feature of this sector is that it is diverse: unlike adoption of low-carbon fuels and feedstocks, and CCS. electricity or buildings, for example, whose emissions Energy efficiency, waste heat recovery, and accelerated come from a relatively small set of activities, industrial adoption of advanced technologies such as additive activities and infrastructure are designed around a large manufacturing, can significantly reduce energy demand set of processes. Some of these processes might have and lower costs to businesses. Material efficiency relatively straightforward substitutes, but in other cases incorporates structural changes in manufacturing that either those substitutes may not exist yet or might be include product recycling and reuse, material substitution, higher cost. In some cases, alternate sources of process and demand reduction. Electrification of heated, fuel- heating may need to be identified. In other cases, CCS consuming industrial processes and equipment is a viable applications may be needed but these may be expensive pathway for some subsectors, such as light industry. or infeasible at existing production facilities. At the Low-carbon fuels and feedstocks, including clean hydrogen same time, scaling up of material efficiency could be and low-carbon biofuels, can reduce emissions from challenging because of product design limitations or processes that are difficult to electrify. Finally, CCS can be consumer demand. Many of these challenges also used for emissions that are hard to abate through other affect the non-CO2 emissions from industry, which are means, particularly in the cement, chemicals, and iron discussed further in Chapter 5. and steel industries. Increased investments in research, development, demonstration, and deployment will advance In response to these challenges, the industrial energy technologies in production of iron and steel, cement, transition can be enabled to decarbonize at a sufficiently chemicals, and other industries, enabling these sectors to rapid pace through a diverse set of approaches tailored to adopt low-carbon production. 34 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S CHAPTER 5: REDUCING NON-CO2 EMISSIONS THROUGH 2050

5.1 INTRODUCTION Non-CO2 GHGs make up 20% of the U.S. contributions to global warming [27]. Non-CO2 GHGs are highly potent heat trapping gases, many of which have greater near-term climate impacts than CO2 [36]. As shown in Figure 11, three gases make up the majority of non-CO2 GHG emissions in the United States: methane (CH4), nitrous oxides (N2O), and fluorinated gases (including HFCs) [27]. The three sources that produce the largest proportion of emissions are soil management (i.e. agriculture and land use), livestock, and energy. While mitigation opportunities exist for many sources of non-CO2 GHG emissions, costs and applicability vary. Because it is challenging to eliminate all of these sources, some remaining non-CO2 emissions will need to be offset in 2050 by net-negative CO2 emissions. This analysis estimates that the total technical potential Figure 11: Sources of U.S. Non-CO2 GHG Emissions, 2019. for non-CO2 GHG mitigation across all sectors is Contribution to 2019 U.S. GHG emissions from non-CO2 approximately 35% without reducing the underlying sources partitioned by type and sector. The contributions are shown in CO2 equivalent, meaning that they are represented activities [36]. Reducing the use of fossil fuels through in proportion to their global warming contribution 100 years efficiency and fuel switching also has the potential after emission. Approximately half of the global warming contribution of non-CO2 gases in 2019 came from methane, to further drive down non-CO2 GHG emissions by with nitrous oxide contributing the second most, followed by 19% given the relationship between fugitive methane fluorinated gases. 35 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S emissions from the extraction, processing, and end- development of new or more effective mitigation use of fossil fuels. These reflect multiple technological technologies and approaches. In addition, in a way that options that United States can use to achieve the is similar to the industrial energy emissions described in necessary reductions in non-CO2 GHG emissions to Chapter 4, the sources of non-CO2 emissions are diverse. reach net-zero total emissions by 2050 (Figure 12). This means that individual strategies must be developed Under these scenario assumptions, there remain non- for each sub-sector and gas. CO2 GHG emissions in the 2030 and 2050 timeframes, which must be offset by carbon dioxide removal. In light of these challenges, this LTS analysis of non- CO2 GHG mitigation potential assumes only modest Reductions in non-CO2 emissions face several technological and cost improvements over time. Because challenges. First is an underdeveloped set of mitigation these assumptions may be conservative, additional, strategies in certain subsectors. In part because of lower-cost, and more rapid reductions could be realized, a lack of historical focus on non-CO2 reductions, the and this will remain an area of active inquiry. Achieving set of available mitigation approaches for these gases more significant long-term reductions of non-CO2 GHG is still relatively small and, in many cases, in earlier emissions will require major technological advances stages of technological development. This means and new, or more effective, backstop mitigation options. that through 2050, overall non-CO2 emissions can be In sectors with less developed current approaches, held roughly constant by deploying currently available this could include new research and development into mitigation technologies. Achieving long-term reductions identifying and commercializing new technologies of non-CO2 emissions below current levels requires to reduce non-CO2 emissions. In other sectors, new Non-CO2emissions (Million metric tons CO 2equivalent) 600 Methane 400 Nitrous Oxide 200 Fluorinated gases 0 2005 2020 2050 Figure 12: Pathways for Non-CO2 Reductions from 2020 to 2050. This figure shows the range of pathways available for non-CO2 mitigation from today to 2050 across all modeled scenarios. In all scenarios there is significant reduction from the 2020 reference, highlighting the importance of non-CO2 abatement. 36 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S mitigation options are under development and nearing gas, such as some of the methane and N2O from commercialization that could result in large volumes the agriculture sector, cannot be abated in the 2050 of non-CO2 mitigation and further reduce non-CO2 timeframe even after applying all available mitigation emissions (see Box 4). technologies, and will have to be offset by negative CO2 emissions.

5.2 KEY ABATEMENT OPPORTUNITIES

5.2.1 METHANE Potential reductions in non-CO2 gases can come from a diverse set of actions, and these actions together Methane is a potent GHG and accounts for about half of aggregate to significant levels (Figure 13). Technical the current observed warming5 of 1.0°C, according to the potential includes technologies like anaerobic digestion latest report of the Intergovernmental Panel on Climate of manure in the agricultural sector and leakage 5 Greenhouse gas emissions in total have contributed 150% of the observed detection and mitigation in the oil and gas sector. warming of 1.0⁰C, but emissions of cooling aerosols have counter-acted As discussed above, some portion of each non-CO2 some of that warming. 800 Mitigation >$100 Mitigation Technical Potential (MtCO2equivalent) 600 Mitigation <$100 Mitigation >$100 Mitigation <$100 400 Mitigation >$100 Residual Residual 200 Mitigation <$100 Residual 0 Methane Nitrous oxide Fluorinated gases Figure 13: Non-CO2 Mitigation Technical Potential by Gas (MtCO2e) in 2050. This figure shows potential reductions in 2050 from non-CO2 emissions in methane, nitrous oxide, and fluorinated GHGs. It is constructed from abatement cost curves using technologies like anaerobic digestion of manure in the agricultural sector and leakage detection and mitigation in the oil and gas sector. Some abatement technologies are negative cost and many cost less than $100 per metric ton of CO2e. Technical abatement potential is most significant for methane and fluorinated gases. 37 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S 150 Coal Mining Croplands Landfills Break-even Price ($/tCO2e) 100 Livestock Oil and Natural Gas Rice Wastewater 50 0 0 100 200 300 Methane Emissions Reductions (MtCO2e) Figure 14: 2050 Methane Abatement Potential in the United States. This figure shows sources of methane abatement potential in 2030 in the United States [36]. This marginal abatement cost curve indicates the price at which methane mitigation from various sources of methane are cost-effective. This figure does not include additional abatement that can be achieved by reducing the underlying activities that drive emissions. These additional reductions from activity driver changes are included in the GCAM modeling and reflected in Figure 12. Change [1]. Methane is primarily generated by fossil and natural gas typically fall into three categories: fuel energy operations (oil, gas, and coal), waste equipment modifications or upgrades; changes in operations, and livestock and agricultural operations. operational practices, including directed inspection, There are cost effective methane abatement options repair and maintenance (DI&M); and installation across all these sectors [36]. Figure 14 shows 2050 of new equipment [35]. Abatement measures methane abatement potential by source. are available to mitigate emissions associated with a variety of system components, including Methane mitigation opportunities by sector include: compressors, engines, dehydrators, pneumatic • ENERGY SECTOR METHANE. Energy sector fugitive controls, pipelines, storage tanks, wells, and others. methane emissions result from operations in the oil Commercially-available mitigation technologies can and natural gas sector and the coal mining sector. also recover and reduce CH4 emissions from coal In some cases, a large proportion of oil and gas mining operations. These reduction technologies methane emissions come from a small number consist of one or more of the following primary of sources. Methane mitigation measures in oil components: a drainage and recovery system to 38 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S remove CH4 from the underground coal seam, an end use application for the gas recovered from the GLOBAL drainage system, and/or a ventilation air methane (VAM) recovery or mitigation system [35]. The CH4 mitigation potential from the energy sector at METHANE $100/tCO2e is 144 million metric tons of carbon dioxide equivalent (MtCO2e) or approximately 43% of 2030 energy sector non-CO2 GHG emissions PLEDGE and remains an important source of potential mitigation through 2050. • WASTE METHANE. Landfills produce CH4 and other landfill gases through the natural process of In September 2021 at the Major Economies Forum, the bacterial decomposition of organic waste under United States and European Union jointly announced anaerobic conditions. Landfill gases are generated the Global Methane Pledge. As of October 2021, over a period of several decades, with flows usually over 30 supportive countries, representing well over beginning within 2 years of disposal. Abatement 30% of global methane emissions and 60% of global options to control landfill emissions are grouped into three categories: (1) collection and flaring, GDP, had already joined—with many more expected. (2) landfill gas (LFG) utilization systems, and Countries joining the Global Methane Pledge commit to (3) enhanced waste diversion practices (e.g., a collective goal of reducing global methane emissions recycling and reuse programs) [35]. Within the by at least 30% from 2020 levels by 2030. They also waste category, wastewater treatment is the commit to moving towards using highest-tier inventory second most important source of non-CO2 GHGs. methodologies to quantify methane emissions, with a Methane emissions in wastewater treatment could particular focus on high emission sources. be significantly reduced by 2050 through currently Delivering on the Pledge would reduce warming by at available mitigation options, such as anaerobic least 0.2°C by 2050. In addition, it would prevent over biomass digesters and centralized wastewater 200,000 premature deaths, hundreds of thousands treatment facilities. Improved operational practices, of asthma-related emergency room visits, and over 20 such as controlling dissolved oxygen levels during million tons of crop losses a year by 2030 by reducing treatment or limiting operating system upsets, can ground-level ozone pollution caused in part by methane. also help reduce N2O emissions from wastewater treatment [35]. The CH4 mitigation potential The United States is pursuing significant methane from the waste sector non-CO2 GHG at $100/t reductions on multiple fronts. The Long-Term Strategy is 8 MtCO2e or 6% of total 2030 waste sector analysis shows that the United States can do its part emissions and remains an important source of to meet the global goal of the Global Methane Pledge potential mitigation through 2050. by reducing domestic methane emissions by over • LIVESTOCK METHANE. Emissions from livestock 30% below 2020 by 2030. This level of reduction include enteric fermentation and manure would avoid 11,000 premature deaths, 1,600 asthma- management. Enteric fermentation is a normal related emergency room visits, and 4.1 million tons of mammalian digestive process, where gut microbes agricultural losses per year in the United States. produce CH4. Livestock manure management produces CH4 emissions during the anaerobic 39 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S decomposition of manure and N2O emissions Nitrous oxide mitigation opportunities by sector during the nitrification and denitrification of the include: organic nitrogen content in livestock manure and urine [35]. Without altering underlying demand, • AGRICULTURAL NITROUS OXIDE. Agriculture is the the mitigation potential of livestock methane at source of over 82% of nitrous oxide emissions. $100/t is 70 MtCO2e or 27% of 2030 livestock Most N2O is produced in soils by bacteria through non-CO2 GHG emissions and remains an the processes of nitrification and denitrification important source of potential mitigation through which occur with fertilizer application. It is also 2050. emitted in lesser amounts from livestock waste, rice production, and soil management such as • CROPLAND AND RICE PRODUCTION METHANE. draining, irrigation, and land use change. Nitrous The anaerobic decomposition of organic matter oxide emissions can be mitigated by changing (i.e., decomposition in the absence of free fertilizer management practices to increase the oxygen) in flooded rice fields produces CH4. efficiency of plant uptake of nitrogen [35]. Practices GHG mitigation scenarios include several factors include precision agriculture, using nitrification that influence the amount of CH4 produced and inhibitors, and splitting annual applications into carbon sequestration in soils, including water seasonal applications. The mitigation potential from management practices and the quantity of the agriculture sector at $100/t is 8.8 MtCO2e, organic material available to decompose [35]. The which is 2.5% of 2030 nitrous oxide emissions mitigation potential from the agriculture sector at from agriculture [36] and remains a small source of $100/t is 1.7 MtCO2e or 1% of 2030 agricultural mitigation through 2050. CH4 emissions [36]. • NITRIC AND ADIPIC ACID PRODUCTION. Nitric acid is an inorganic compound used primarily

5.2.2 NITROUS OXIDE to make synthetic commercial fertilizer. Adipic Nitrous oxide (N2O) is a potent GHG with 298 acid is a white crystalline solid used as a feedstock times more warming potential than carbon dioxide in the manufacture of synthetic fibers, coatings, and a long atmospheric lifetime (approximately 114 plastics, urethane foams, elastomers, and synthetic years). N2O comes from natural and anthropogenic lubricants. The production of these acids results sources and is removed from the atmosphere in nitrous oxide emissions as a by-product. By mainly by photolysis (i.e., breakdown by sunlight) 2030, about two-thirds of nitrous oxide emissions in the stratosphere. In the United States, the main from this source category are projected to be from anthropogenic sources of N2O are agricultural soil adipic acid production driven by high demand management, livestock waste management, mobile growth compared with about one-third from nitric and stationary fossil fuel combustion, adipic acid acid production. Abatement measures applicable production, and nitric acid production. N2O is also to nitric acid are characterized by the point in the produced naturally from a variety of biological sources production process they are implemented, but in soil and water, although this report only covers generally involve catalytic decomposition of the man-made sources only. Figure 15 shows 2050 nitrous oxide by-products [35]. Thermal destruction nitrous oxide abatement potential by source. is the abatement option applied to the adipic acid production process. The mitigation potential from nitric and adipic acid production at $100/t is 17.7 MtCO2e or 62% of total sectoral 2030 nitrous oxide emissions [36] and remains an important source of mitigation through 2050. 40 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S

5.2.3 FLUORINATED GASES to replace ozone-depleting substances (ODS) in refrigeration, air conditioning, aerosols, fire suppression, Fluorinated gases (F-GHGs) are anthropogenically- and as foam blowing agents. HFC emissions reductions generated and used in a range of applications. are achievable by preventing or reducing leaks and Sometimes referred to as “climate superpollutants,” transitioning to the use of alternatives with low global they are highly potent GHGs, capable of trapping warming potential (GWP). Figure 16 shows 2050 hundreds to thousands of times more heat per fluorinated GHG abatement potential by source. molecule than carbon dioxide. According to the 2021 Inventory of U.S. Greenhouse Gas Emissions Under the American Innovation and Manufacturing and Sinks [27], most fluorinated gases emitted are (AIM) Act of 2020, in September 2021 the EPA hydrofluorocarbons (HFCs). A substitute for ozone- finalized a rule that phases down HFCs through an depleting substances, HFCs were initially developed allowance allocation and trading program. The AIM 150 Livestock Nitric Adipic Rice Break-even Price ($/tCO2e) 100 Croplands 50 0 0 10 20 30 40 50 N2O Emissions Reductions (MtCO2e) Figure 15: 2050 Nitrous Oxide Abatement Potential in the United States. This figure shows sources of nitrous oxide abatement potential in 2050 in the United States. This marginal abatement cost curve indicates the price at which nitrous oxide mitigation from various sources of are cost-effective. This figure does not include abatement associated with a reduction of the underlying activities that drive emissions. These additional reductions from activity driver changes are included in the GCAM modeling and reflected in Figure 11. 41 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S Act, along with this rule, provides the domestic legal 5.2.4 BLACK CARBON framework to implement the phasedown of HFCs outlined in the Kigali Amendment to the Montreal Black carbon (soot) is not a GHG, but a powerful Protocol, which 124 countries have joined to date. The climate-warming aerosol [1] that is a component of fine phasedown will effectively decrease the production and particulate matter (PM2.5) that enters the atmosphere import of HFCs in the United States by 85% by 2036 on through the incomplete combustion of fossil fuels, the same step-down schedule as laid out in the Kigali biofuels, and biomass [46]. The Arctic is particularly Amendment and is expected to result in reductions of vulnerable to warming from black carbon. Black carbon more than 4.5 billion metric tons of carbon dioxide- is also a local air pollutant, contributing to major health equivalent by 2050. impacts that disproportionately affect low-income and marginalized communities [47]. Transitioning from Achieving significant HFC reductions by 2050 will fossil fuel combustion for electricity and transport rely on a three-pronged approach. First, phase down (on-road and off-road) to cleaner alternatives is key to the production and import of HFCs. Second, address reducing black carbon emissions in the United States. the existing stock of refrigerators and air conditioners, Flaring in the oil and gas sector is an additional source which already contain HFCs and have potential to leak of black carbon. The EPA estimates that U.S. black into the atmosphere over the coming decades. Third, carbon emissions have been reduced significantly since deploy the next generation of low-GWP alternatives 2013 primarily due to reductions in the road and off- to existing HFCs. Additional RD&D support to ensure road transport sectors, largely through policies and new alternatives to HFCs continue to enter the market strategies to reduce the emissions from mobile diesel may also be important, including both new molecules engines. Strengthening particulate matter standards and new uses for existing alternatives. Combining these and addressing legacy diesel vehicles and emissions approaches, the mitigation potential of HFCs at less associated with ports, including from ships, port than $100/t is 84 MtCO2e which is 39% of total 2030 equipment, and trucks, would further contribute to sectoral emissions and remains an important source of meeting national climate, health, and climate justice mitigation through 2050. goals. 42 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S 150 Aerosols Aluminum Electric Power Systems Break-even Price ($/tCO2e) 100 Fire Extinguishers Foams Magnesium Photovolatics Refrigeration and AC 50 Semiconductors Solvents 0 40 80 120 160 F-Gas Emissions Reductions (MtCO2e) Figure 16: 2050 Fluorinated GHG Abatement Potential in the United States: This figure shows sources of fluorinated GHG abatement potential in 2050 in the United States. This marginal abatement cost curve indicates the price at which F-GHG miti-gation from sources of are cost-effective. This figure does not include additional abatement that can be achieved by reducing the underlying activities that drive emissions. These additional reductions from activity driver changes are included in the GCAM modeling and reflected in Figure 11. 43 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S NON-CO 2 BREAKTHROUGH TECHNOLOGIES: REDUCING METHANE FROM ENTERIC FERMENTATION While many low-cost abatement opportunities exist today for non-CO2 emissions—and are reflected in this analysis—some specific applications do not have current, low-cost mitigation opportunities. A renewed focus on research and development for these EPA and other researchers are collecting information to remaining non-CO2 emission processes could potentially assess these technologies. Asparagopsis, 3-NOP, and other provide significant benefits as well as dramatically lower the technologies that may increase non-CO2 GHG mitigation. The costs of reductions. While not required to achieve our 2050 science and economics of Asparagopsis is far from settled, net-zero goal, such advances could provide valuable additional with important remaining questions surrounding the costs to flexibility in how that goal could be achieved. grow, harvest, and process Asparagopsis into feed, to assess scalability to produce marketable quantities (or directly One example of this kind of positive breakthrough may be synthesize bromoform); and to assess the long-term tolerance emerging. Without a technological advance, there is limited of cattle and the applicability to different production and methane abatement potential from enteric sources—cattle, regulatory systems. If national-scale developments prove sheep, and goats—which produce methane as part of their technically and economically feasible, Asparagopsis could digestive process. While improving productivity can, to a potentially decrease livestock emissions by as much as 160 limited extent, help reduce methane emissions per pound MtCO2e (60%) in 2030. 3-NOP has shown strong potential for of beef or gallon of milk, it does not provide a route to methane reduction across multiple trials, with over 45 peer- major reductions. However, recent research suggests that reviewed papers examining numerous aspects of the potential new technologies might be able to offer greatly increased impacts of this additive. 3-NOP has been shown to be effective effectiveness. New discoveries of low-cost feed additives in reducing enteric emissions by about one-third in dairy cows indicate the possibility that these would unlock large and up to 70% in beef finishing trials without unacceptable additional potential emissions reductions. Examples of these side-effects. More innovation and testing are needed to further additives include red algae (Asparagopsis) and a compound, develop these solutions and bring them to market. 3-Nitrooxypropanol (3-NOP). 44 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S CHAPTER 6: REMOVING CARBON THROUGH 2050 AND BEYOND

6.1 THE NECESSITY OF CO REMOVAL TO REACH 2 NET-ZERO Efficiency, electrification of end uses, decarbonization of the electricity sector, and reduction in non-CO2 emissions are the most important CO2 levers for decarbonizing the U.S. Non-CO2 economy and will be the emphasis of Land Sink the overall strategy to reach net-zero Net Emissions (Gigatons CO2e)

5.0 CDR by 2050. Net-GHG Figure 17: Balancing Emissions Reductions and Removals to Reach 2050 Net-Zero. This figure shows the range of outcomes 2.5 for mitigation pathways as well as removals pathways to achieve net-zero by 2050. Some sources of non-CO2 emissions, and potentially some CO2 emissions, cannot be reduced to zero, and these must be balanced by CO2 removals. CO2 removals can happen through land sinks, such as forest growth 0.0 and soil carbon sequestration, or through carbon dioxide removal technologies such as direct air capture or carbon capture and sequestration in industry or electricity generation. Note: Historical data in this figure are from the U.S. GHG Inventory (2021). 2005 2020 2050 45 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S However, as mentioned in previous sections, some Though the overall U.S. lands net carbon sink has been activities will be difficult to decarbonize completely relatively stable for recent decades, the future of that by 2050. Because of this, removals of CO2 from the sink is uncertain [50], and several challenges exist to atmosphere will be critical to enable the United States bolstering it and expanding it significantly. Substantial to reach net-zero by 2050 and to achieve net negative forested lands, including large portions of our Western emissions thereafter. This implies an important role public lands, now have older forests which sequester for the land sector, which can increase natural carbon less CO2 and are more vulnerable to natural disturbances dioxide removal and storage from the atmosphere, [51]. Moreover, increased levels of disturbances—fires, as well as a role for technologies including advanced insects, diseases, droughts, and storms—are expected carbon dioxide removal (CDR) technologies. Carbon in the future, along with other potential ecosystem dioxide removal technologies will only deliver desired changes such as CO2 fertilization, due to climate change. societal and environmental benefits if their deployment These changing environmental conditions will also is well-designed and well-governed. Figure 17 shows dictate the future degree of mitigation and adaptation the range of outcomes for mitigation pathways as well capabilities and opportunities [53]. These factors are as removals pathways to achieve net-zero by 2050. already having an impact: total carbon removal in the land use, land use change, and forestry (LULUCF) sector

6.2 MAINTAINING AND ENHANCING CO2 has decreased by approximately 11% since 1990 [27]. In addition, U.S. lands include diverse ecosystems which REMOVAL THROUGH THE U.S. LAND complicates efforts at comprehensive and timely data CARBON SINK collection, as well as monitoring and verification of U.S. lands provide myriad social, economic, and baseline emissions, sequestration, and GHG outcomes environmental benefits. The United States has 8% of of mitigation activities. In addition, the land base is the world’s forests (310 million ha) and 8% of global finite in terms of its ability to continue to provide food, agricultural lands (400 million ha) [48]. These lands fiber, and essential ecosystem and biodiversity services provide essential ecological, economic, and non- while also supporting potentially increased levels of monetary social services, and will also be critical in carbon-beneficial biomass for energy production and supporting economy-wide decarbonization over the carbon removal strategies through bioenergy and next 30 years and beyond. CCS. In addition, CO2 removals via natural systems can be more variable than those in other sectors or Our lands, and human activities on those lands, emit technologies, as they are subject to reversals, e.g., from CO2 to the atmosphere through land conversion, soil natural disturbances like fires, storms, and pests or degradation, and forest loss and degradation, but also from individual landowners changing land management remove it via photosynthesis and store it as carbon practices. Also, with respect to policies, U.S. lands are in trees, other vegetation, soils, and products. For the held and managed for different objectives by a range last several decades, U.S. lands have been a net carbon of different stake-holders that operate under different sink, meaning more CO2 is sequestered than emitted legal, social, and environmental norms. Achieving land annually from the land sector. This historic trend was sector goals necessitates coordination and cooperation due in part to millions of acres shifting into forest with millions of private landowners, private sector from other uses and the conservation and continued corporations, and non-governmental organizations, regrowth of trees on already forested lands, much of as well as Tribal, local, state, and federal government which had been deforested before the early 1900s [49]. agencies. Today’s forest sink is still increasing but at a decreasing rate [27]. In 2019, the U.S. land carbon sink yielded net These challenges may be counterbalanced, at least in CO2 removals of 813 MtCO2e, offsetting approximately part, by changes in the economy, policy actions, and 12.4% of economy-wide GHG emissions [27]. investments. Achieving significant land carbon benefits 46 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S by 2050 and beyond requires targeted, science-based • AGRICULTURAL LANDS. There are potential action in the near term and over the next several substantial GHG mitigation and increased removal decades. These actions must not only work to enhance opportunities on U.S. croplands and grasslands our land carbon sink but also ensure our lands continue via activities that conserve and/or increase soil to provide a host of other benefits, including provision carbon and employ innovative lands management of goods, jobs, ecosystem services, recreational and approaches such as agroforestry, rotational grazing, spiritual spaces, and biodiversity preservation. For reduced tillage, residue management, and more. example, public and private investments in natural climate solutions (e.g., augmented federal programs, • BIOENERGY. Biomass is a key component of efforts private entities’ involvement in land conservation and to decarbonize the energy sector, as studies have offset markets) can increase acreage, productivity, shown that higher levels of biomass availability and overall health of U.S. forested lands [52] [54]. and use can offer lower-cost mitigation than Strengthening existing and supporting new emerging decarbonization strategies without biomass (e.g., [60] [61]). Bioenergy can be particularly useful in timber markets, especially in the fast-growing climes of Southeast United States, can also help maintain and deep decarbonization scenarios, as it can be used to expand forested lands [55]. Policies, incentives, and decarbonize energy use in multiple sectors through investments that can support an enhanced sink through a range of different energy pathways (e.g., liquid activities such as reforestation and soil carbon retention fuel, biogas, electricity, and hydrogen production) will be central. Low- or zero-carbon biomass for and it can be used in combination with CCS to bioenergy and BECCS applications can also contribute to further reduce GHG emissions [9]. Efforts aimed at emissions reductions. These policies and programs must employing biomass use for energy should include include safeguards to minimize issues such as potential safeguards to ensure actual emissions reductions reversals and leakage to the extent possible, and include to the atmosphere and reflect consideration of the efforts to bolster our ability to monitor, track, and verify many non-carbon consequences of large-scale emissions reductions at different scales. biomass production and use (e.g., competition with food production and biodiversity and broader Specific areas of focus include: ecosystem impacts). • FORESTS. GHG benefits in the relative near term can come from activities such as avoided forest land 6.3 ASSESSING POTENTIAL LAND SECTOR conversion to other uses. Some forest sector actions, PATHWAYS such as longer harvest rotations or increased carbon The LTS pathways explored for this study include storage in harvested wood products and substitution varying degrees of private and public investment of more fossil-intensive construction materials with in natural climate solutions in both forestry and wood products, can yield both near- and long-term agriculture, such as improved forest management, benefits [56]. There are considerable opportunities fire reduction activities, afforestation, and improved for reforestation in the United States [57], potentially agricultural soil management. To better reflect the up to 133 million acres [58]. Other activities like uncertainties associated with estimating the complex afforestation, improved forest management and carbon dynamics of different terrestrial ecosystems and reduced natural disturbances (e.g., avoided forest related market interactions, and the potential extent fires via fuel treatments such as thinning and of land use change between sectors, the U.S. LULUCF prescribed fires) can offer incremental near-term net projections through 2050 are presented as a range, carbon benefits and may yield substantial benefits in as seen in Figure 18. This range was developed via a the long term [59]. collaborative multi-agency effort using different models reflecting alternate modeling techniques. 47 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S 0 LULUCF Sink (Mt CO2equivalent) BAU Range -500 -1,000 NCS Action Range -1,500 2005 2020 2030 2040 2050 Figure 18: Land Use, Land Use Change, and Forestry CO2 Business as Usual and LTS Action Projections with Uncertainty Ranges. There is a range of possible CO2 outcomes for both the reference case and the Long-Term Strategy action case. Historic values are from the U.S. GHG Inventory [27] and projected values are derived from a range of land sector models. Estimates include forest ecosystem carbon pools, harvested wood products carbon storage, and land use and land use conversion fluxes across land types. The analysis is based on several sectoral lands models 6.4 CO2 REMOVAL THROUGH ENGINEERED including the Global Timber Model (GTM), the Forestry APPROACHES and Agriculture Sectoral Optimization Model with Greenhouse Gases (FASOM-GHG), three U.S. Forest In addition to the land sector CO2 reduction potential, Service models (the Resources Planning Act (RPA) technological CO2 removal options could be deployed Forest Dynamics model, the RPA Land Use Change over coming decades to support the net-zero emissions model, and the Forest Resource Outlook model), and goal. While some technologies for such activities do USDA agricultural soil carbon projections, to provide exist, advanced CDR technologies are today in various a range of potential land sink projections in 2050. stages of development. As shown in Figure 18, there is a significant range of At this early stage, it is difficult to estimate exactly possible land sector pathways which could enable the which combinations of technologies might be most United States to meet its net-zero goal by 2050. achievable and appropriate in terms of deployment, but potential strategies include: 48 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S • BIOMASS CARBON REMOVAL AND STORAGE. but the potential capacity of CO2 mineralization This is a carbon dioxide removal approach where could be quite high [62]. CO2 is produced from the combustion, gasification, or other conversion of low- or zero-carbon biomass, • OCEAN-BASED CDR. for example to generate electricity or produce This is a CDR approach that removes dissolved CO2 hydrogen, and the resulting CO2 emissions are from the ocean. Ocean-based approaches include captured and then stored in a manner that prevents nature-based approaches (e.g., kelp afforestation), it from reentering the atmosphere. Specifically, engineered approaches (e.g., electrochemical CO2 the captured CO2 emissions are compressed into capture from seawater), or a combination of the a fluid and transported to a specified site, where two (e.g., growing macroalgae and sinking it to the they are injected into deep, underground geological sea floor). Ocean-based CDR is in early stages of formations, such as former oil and gas reservoirs or research and development and merits closer study. deep saline formations for long-term storage. CDR The early stages of these potential removal strategies efforts using biomass as an input, such as biomass present some visible challenges to large scale use for energy with CCS, should include safeguards deployment by 2050. For example, there is currently to ensure actual emissions reductions to the no large-scale proof of concept for DAC technology atmosphere (e.g., including, to the extent possible, or bioenergy with carbon capture and storage, making robust GHG accounting), and reflect consideration it difficult to determine how well the technology can of the many non-carbon consequences of large- scale up and what the true cost and adverse impacts scale biomass production and use (e.g., competition of the technology are at large scale. In parallel, some with food production and biodiversity and broader technical obstacles remain. Research to date indicates ecosystem impacts) [61]. that DAC requires high energy use for each metric ton • DIRECT AIR CAPTURE AND STORAGE (DACS). of CO2 removed. Other technologies, such as enhanced This is a technology that captures CO2 emissions mineralization, are still in nascent stages of research and directly from ambient air (instead of from point development, so the potential magnitude of reductions sources, such as power plants or industrial facilities), and the timeframes over which these technologies might via solvent, solid sorbent, or mineral processes. deliver reductions is unknown. Other uncertainties The captured CO2 is then either compressed and associated with large-scale deployment of some sequestered permanently in a geological setting or technologies like BECCS could have broader upstream converted into a usable material such as a synthetic GHG and other environmental implications (e.g., life- aggregate in concrete production. cycle GHG outcomes of biomass production). • ENHANCED MINERALIZATION. Addressing these challenges and uncertainties This is a CDR approach that accelerates natural will require a substantial and integrated research, geologic processes around mineral reactions with development, and deployment strategy. As one step CO2 from the ambient air, leading to permanent towards the development and deployment of new carbon storage through carbonate rock. There are approaches to CDR, Congress recently created the several types of mineralization processes: in situ (e.g., Carbon Dioxide Removal Task Force to “establish a CO2 reactions in geologic formations underground), research, development, and demonstration program…to ex situ (e.g., CO2 reactions that involve extraction, test, validate, or improve technologies and strategies to transport, and grinding of minerals), and surficial remove carbon dioxide from the atmosphere on a large (e.g., ambient weathering using CO2-enriched fluids scale” [63]. However, additional actions will be needed and on-site minerals like mine tailings). Research and to understand and innovate on CDR options, to reduce development for enhanced mineralization is still early, uncertainties, and to ensure sustainable outcomes. 49 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S CHAPTER 7: BENEFITS OF CLIMATE ACTION THROUGH 2050

7.1 THE BENEFITS FROM A TRANSFORMED, change, which are already being felt. For example, air NET-ZERO ECONOMY pollution kills thousands of people in the United States annually [64] and millions worldwide, particularly in Bold and timely climate action towards net-zero the lowest-income countries, and ongoing international will help the United States and the world avoid the conflicts are exacerbated by climate change [65]. worst impacts of climate change—and provide a The longer action is delayed, the faster the transition transformative boost to the U.S. economy and the must be, potentially causing severe disruption [66]. health and well-being of all Americans. Reductions Moreover, delay incurs more severe consequences such in fossil fuel combustion and reductions in non-CO2 as changed weather regimes (including new extremes emissions will improve air quality and reduce the [67]), higher sea level rise, greater ocean acidification dangerous risks of climate change. The expansion of [68], and a higher likelihood of reaching catastrophic new industries will create high-quality jobs, maintain damages or “tipping points” and potentially irreversible economic competitiveness, and enable sustainable, ecological impacts. These impacts have health and broad-based economic growth. The benefits from this economic costs for all, but they are borne unequally, transformation are not constrained by political borders: with greater consequences for low-income countries U.S. action and ambitious action from other countries globally and communities of color, low-income will have positive spillover effects including driving communities, and indigenous communities within the down the cost of carbon-free technologies and reducing United States [69]. For example, Black children are the costs of climate induced disasters and conflicts 34-41% more likely to live in areas with the highest around the world, particularly for lowest-income projected increases in asthma diagnoses due to nations that are least able to adapt. climate-driven changes in particulate air pollution [68]. These impacts are addressed more completely in the In addition to the economic gains, action to meet the National Climate Strategy [2]. net-zero goal will, combined with global efforts, allow the United States to avoid the worst impacts of climate 50 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S

7.2 IMPROVEMENTS IN PUBLIC HEALTH disease; and reduced food and water quality. In addition to immediate fatalities associated with the events Climate-driven changes in weather, human activity, and themselves, extreme weather events can exacerbate natural emissions are all expected to impact future air underlying medical conditions and disrupt critical health quality across the United States [70]. Acting now on care, resulting in potentially lasting consequences. climate change and decarbonizing our energy sector Furthermore, temperature increases have been linked will result in vastly cleaner air, immediate and long-term to increases in premature death due to exposures to improvements in public health, and ecological benefits both cold and heat extremes; additionally heat exposure throughout the United States. These benefits arise from has led to increases in emergency room visits and several sources. hospital admissions for heat-related illnesses such as REDUCING GHGS CAUSES REDUCTION IN POLLUTANTS cardiovascular and respiratory conditions, kidney failure, HARMFUL TO HEALTH, WELL-BEING, AND PRODUCTIVITY. and preterm birth, among others [77]. There are large Reducing GHGs to net-zero by 2050 will disparities in urban heat environments in many U.S. cities simultaneously reduce other pollutants, including that put lower-income people and people of color at particulate matter (PM), ozone and PM precursors, higher risk of heat exposure [79]. Changes in temperature nitrous oxides (NOx), sulfur dioxide (SO2), and other and rainfall patterns have been implicated in the spread air toxics. These benefits will be more significant in of some infectious diseases in some areas, including communities overburdened by air pollution. Ozone mosquito-borne Zika and West Nile viruses, by creating and PM are air pollutants that adversely affect human conditions that promote the expansion, abundance, and health and are monitored and regulated with national activity of certain disease vectors [76] [78]. Waterborne standards [71]. Human exposures to these pollutants diseases have been associated with excessive rainfall as have been associated with premature death, hospital well as drought conditions. Water temperature increases admissions, and respiratory ailments, among others. have contributed to the growth of toxic algal blooms and A total of 60,600 deaths in the United States in 2019 harmful pathogens (e.g., Salmonella and Campylobacter), alone were attributable to PM and ozone exposure [73]. the presence of which can adversely affect food The energy sector accounts for 80% of emissions of security and availability [77]. As for air pollution, the NOx and 96% of SO2 [70]. As the economy transitions benefits of action to reduce impacts will be strongest to carbon-free energy, reductions in air pollution are in communities that are historically disadvantaged, also expected to increase productivity of the workforce low-income, and/or lack access to health services and due to health improvements. Beyond the traditional prevention and are therefore most vulnerable to climate focus on mortality impacts, there is emerging evidence change [68]. For example, Hispanic and Latino individuals that minor health impacts from air pollutants can also are 25-43% more likely to currently live in areas with the adversely affect educational attainment and reduce highest projected labor hour losses in weather-exposed labor productivity, e.g., fewer tasks completed and industries due to increases in high-temperature days. fewer hours worked [74]. Such improvements would be important because climate projections show a direct 7.3 AVOIDING COSTLY CLIMATE IMPACTS impact of future extreme temperatures reducing hours worked in the economy [75]. Avoiding climate change will provide immediate and sustained benefits to the economy across several REDUCING CLIMATE CHANGE SEVERITY SAVES LIVES categories. Global emissions reductions can substantially AND IMPROVES HEALTH. Climate change threatens reduce the damages of climate change in the United the health and well-being of Americans through States [80]. One estimate shows reduced monetary catastrophic events; increases in heat-related illnesses damages from a subset of climate change impacts of and deaths; increases in vector-, food-, and water-borne $49 billion/year in 2050 and up to $388 billion/year in 51 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S 400 Annual Benefits of Climate Mitigation (Billion 2017$ US) Water Resources Labor Coastal 300 Infrastructure Health Impacts 2090 to the U.S. economy in 1.5°C- 200 compatible scenarios compared to a reference scenario, from factors such as fewer deaths, less damage to infrastructure, and fewer lost 100 wages.6 Similarly, Figure 19 shows the large and increasing benefits that accrue over time to the overall economy from a low-emissions 0 pathway.7 This analysis is only a lower bound estimate as it does not 2050 2070 2090 include a comprehensive accounting of all potential impacts such as other Figure 19: Projected Annual Benefits of Climate Mitigation for health effects, effects on managed and Select Years. Benefits from keeping to a 1.5⁰C trajectory grow unmanaged ecosystems, some indirect significantly over time. U.S. annual economic impacts for a subset of sectors for the Reference minus 1.5°C scenario8. Impacts effects, and social impacts. presented in billions of $2017. 6 The temperature and radiative forcing for the two scenarios are 8 17 U.S. sectors are represented in this figure. Health impacts consist calculated from the median over an ensemble of 600 MAGICC v7.5.1 of the following sectors: extreme temperature mortality, ozone and runs selected to match assessed proxy ranges [112]. For the 1.5°C PM2.5 mortality, valley fever, wildfire health effects, and suppression and scenario, global mean temperature reaches 1.5°C in 2100 with a southwest dust health effects. Coastal impacts consist of the following corresponding radiative forcing of 2.45 Wm-2 and 3.8°C in 2100 with a sectors: coastal property, hightide flooding and traffic, and tropical corresponding radiative forcing of 7.60 Wm-2 for the Reference scenario. storm wind damages. Infrastructure consists of the following sectors: Descriptions of future population, GDP, the transformation of global rail and road infrastructure, electricity demand and supply, electricity temperature change to continental U.S. temperature change, estimation transmission and distribution, and urban drainage. Water resources of sea level rise, and other parameters and assumptions can be found in consist of the following sectors: water quality, winter recreation, and [111]. This framework includes impact estimates that employ a variety inland flooding. Lastly, the labor sector represents lost wages. of assumptions regarding adaptive responses to climate impacts. The general adaptation scenarios considered in the analyses do not capture the complex issues that drive adaptation decision-making at regional and local scales. Adaptation and scenario assumptions used in this analysis: High Tide Flooding and Traffic impacts assume reasonably anticipated adaptation measures; Rail, Roads, Electricity Transmission and Distribution Infrastructure, and Coastal Properties assume reactive adaptation; Extreme Temperature Mortality assumes cities in cooler climates will adapt and become more resilient similar to present day cities in warm climates; and Ozone and PM2.5 Mortality uses 2011 emissions of co-emitted pollutants. The rest of the sectors do not explicitly model adaptation. 7 Damages, and therefore avoided damages, increase over time due to the increasing divergence in global mean temperature change between the two scenarios along with growing populations; more valuable potentially vulnerable infrastructure; and higher valuation of avoided mortality. 52 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S

7.4 ENHANCED CLIMATE SECURITY but drought, floods, and other disasters related to climate change have been associated with large-scale There is a growing body of evidence that climate change displacement of people and, in some cases, this has led can exacerbate conflict and reduce global security. to political instability and conflict. Climate change is a national security threat because it is globally destabilizing, changes military operating Climate change is related to both short-term conditions, and demands new missions [81]. This phenomena such as extreme weather events and means that mitigating the risk of climate change not long-term impacts such as rising sea levels and only delivers ecological, public health, and economic persistent drought. All of these can affect the lives benefits, but also enhances national and global security. and potentially the movements of large numbers of By acting early and leading by example, the United people in a way that can increase stresses within States can build confidence in global efforts to reduce and between countries. Tropical storms, which are the risk of climate change [82]. The risks of a changing expected to become more severe as climate continues climate can make existing conflict more violent, lead to to change (and have already become more severe in the instability, and, through more erratic weather, affect the Atlantic Basin), already can displace large populations. ability of the military to respond to security concerns. Hurricane Katrina, for example, traumatically displaced The U.S. National Intelligence Estimate assessment tens of thousands of people from the city of New is that “climate change will increasingly exacerbate Orleans. In a country with lower capacity to address risks to U.S. national security interests as the physical such crises, a similar event could create climate impacts increase and geopolitical tensions mount about refugees and cause instability. Continued, more how to respond to the challenge” [83]. frequent, or more severe drought is also an expected result of climate change. In agricultural societies, Extreme weather and conditions increasingly severe drought can exacerbate stresses. Drought attributed to climate change already impact U.S. contributed to the current civil war in Syria, causing infrastructure, through the effects of sea level rise, internal destabilization as well as political stresses in storms, and wildfire. The U.S. Department of Defense neighboring countries due to the resulting refugee crisis calls climate change a “top management challenge” [88]. The impacts of long-term changing sea level have because of the threat to operational security and to already led to climate refugees, including in parishes the physical infrastructure of installations [84], and in southern Louisiana [89]—and this can be disruptive finds that climate change is reshaping the geostrategic, across the world. For example, a further sea level rise of operational, and tactical environments with significant six inches (15 cm) could displace millions from the Nile implications for U.S. national security and defense [6]. It Delta in Egypt [90]. Instability in strategically important can also impact military readiness by diverting military regions, even far from the United States, is a national assets and personnel to assist with disaster recovery, security concern. storms, and wildfire impact [85]. Societies can respond to crises like drought and water Experts agree that climate-related events (droughts, stress by strengthening political relationships that storms, wildfires, and flooding) are already contributing can benefit mutual security [91], but, in particular for to conflict [86]. While the main conflict drivers have vulnerable societies, the impacts of climate change may been related to low socioeconomic development, result in increased conflict. Actively working to mitigate low state capability, intergroup inequality, and a climate change along with helping communities to history of conflict, these drivers can be exacerbated build resilience and adapt may reduce the risks of these by disruption related to climate change [87]. Clear conflicts. causal relationships between climate change and specific conflicts are the subject of ongoing research, 53 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S

7.5 BUILDING A STRONGER U.S. ECONOMY the pathway to carbon neutrality more economically and politically feasible [97] [98]. Smart public The revolution in climate solutions has already begun. investments in innovation stimulate private investment The fastest-growing power generation technologies and economic growth and can help establish new (and are solar and wind, with a record-setting 35 GW of often unforeseen) productive industries in the process deployment in 2020, accounting for about 80% of new [99] [100] [101]. One recent study finds social returns capacity [92]. Globally, the zero-emissions vehicle share from investments in research and development are as of new car sales is expected to rise from 2% today to much as four times larger than private returns [102], nearly 30% by 2030 [93], with significantly higher and an analysis of data on 16 advanced countries numbers in the United States in line with reaching between 1980 and 1998 found that a 1% increase 50% new car sales. In these and many other sectors, in public research and development investment the transition to carbon neutrality will accelerate for generated an extra 0.17% in long-run output [103]. The compatibility with international climate targets [94], benefits of accelerating innovation will spill over to our representing rapidly expanding new markets in the international partners, including to developing countries United States and globally. which will be hit hardest by climate damages and can The economic opportunity of decarbonization is least afford to take actions in response. immense. The United States is well-positioned to Although the overall economy will benefit from the incubate new innovators and firms, with a well-trained transition to carbon neutrality, certain fossil fuel- workforce and institutions that have enabled global dependent sectors and regions will have a more leaders in information technology, biotechnology, difficult transition. Some communities are already pharmaceuticals, and other industries [95]. Moreover, experiencing economic challenges from the declines a unique endowment of natural resources makes in fossil fuel-related employment [104], while others geographic regions of the country well-suited to be (predominantly low-income communities, communities hubs of a wide range of carbon-free activities [40]. The of color, and indigenous communities) are experiencing United States can lead in the clean technologies for disproportionate impacts of climate disasters and air the 21st century, manufacturing crucial technologies pollution. A comprehensive policy strategy can support like batteries, electric vehicles, and heat pumps, American workers and firms through the transition, without sacrificing critical worker protections or a fair creating high-quality jobs throughout the country, distribution of benefits of economic activity. including in historically marginalized communities and Because innovation is cumulative and because many in regions that have lost major employers and taxpayers. environmental technologies have returns to scale, investing early in the development of new technologies [96] will boost innovation in climate solutions and make The United States can lead in clean technologies and jobs for the 21st century and is well-positioned to incubate new and innovative firms. 54 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S CHAPTER 8: ACCELERATING GLOBAL CLIMATE PROGRESS With our ambitious NDC target to cut emissions in half with lower climate footprints. And we can develop, or more by 2030, and our goal for net-zero emissions train, and educate workers for productive and healthier no later than 2050, the United States has committed to work in new and fast-growing industries. Undoubtedly, sustained investment in a vibrant clean economy that the U.S. roadmap will evolve as we learn more about the will propel global climate action while improving social, potential for new technologies in diverse applications, economic, and health equity at home. and as new policy platforms are developed over time. The United States intends to regularly review and This report has presented the U.S. Long-Term Strategy update this Long-Term Strategy as needed to consider to achieve these ambitious goals. The road ahead such developments and the latest science. to 2050 contains opportunities, uncertainties, and challenges. The opportunities are clear and broad Given the rapid pace of action in the United States ranging, and collectively offer a pathway to reinventing and other leading countries, if other major economies and reinvigorating the American economy to be adopt similar levels of ambition, the world can keep a equitable, globally competitive, and supportive of safer 1.5°C future within reach. For its part, the United global climate and sustainability goals. It will rely on States currently emits 11% of annual global GHGs American innovation and partnerships across all of (second to China, which emits 27% of the global total), society, including Tribal and subnational governments; so eliminating U.S. emissions by 2050 will make an private sector businesses, industry, and investors; non- important direct contribution to reaching our shared governmental organizations and cultural institutions; global climate goals. However, others must step up with universities, research organizations, and educational both long-term and short-term ambition, and many institutions; and our people. Together, we can meet are already doing so. To date, at least 63 countries the challenges in developing and deploying new clean representing over half current global emissions have technologies at scale. We can discover new and committed to net-zero GHG emissions targets. Many creative ways to provide better services and products more, representing over 70% of global emissions, are in 55 T H E LON G -TE RM STRATEGY O F THE U NITE D STATE S diverse stages of identifying and committing to similar But the United States, EU, UK, Japan, Canada, net-zero targets by mid-century [105] [106] [107]. Republic of Korea, South Africa, and other ambitious These commitments matter: achieving near-net-zero major economies cannot do it alone. Strong 2030 emissions globally by 2050 will dramatically improve NDCs will be required by all G20 economies to cut our chances of limiting global warming to near 1.5°C. global emissions by at least 40% by 2030. Enhanced action by all G20 members to adopt high ambition However, while the rapid expansion of 2050 targets 2030 NDCs and mid-century net-zero commitments and long-term strategies is encouraging, commitments could reduce warming by over 0.5°C and keep 1.5°C to act by 2030 are also critical. Countries representing within reach [108]. Globally, this is the moment for all well over half of the global economy, including nearly the world’s major economies to act to rapidly reduce all the G7 countries, have already put forward strong emissions to meet ambitious 2030 NDC targets and 2030 NDCs. 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