Getting to Net-Zero Emissions by 2050

The United Nations’ Global Climate Change Conference (COP26) will bring together world leaders to discuss how to reduce greenhouse gas emissions to net-zero by the year 2050. A number of expert reports from the National Academies have assessed the latest in climate science, technology options, and socioeconomic dimensions related to that goal. This resource provides an at-a-glance look at findings and U.S. policy-relevant advice from those reports.

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Why Net-Zero Emissions by 2050?

Reduce Impacts of Climate Change
The current greenhouse gas induced warming of Earth is essentially irreversible on human timescales. The amount and rate of further warming will depend on how much more CO2 is added to the atmosphere. A sharp reduction in CO2 emissions is needed to slow climate change and avoid the most severe impacts on weather extremes, ecosystems, human health, and infrastructure.
Meet International Agreements
The 2016 Paris Agreement set an aspirational target of limiting warming to 1.5°C (2.7°F). Meeting that goal will require global emissions to be reduced by about 45 percent from 2010 levels by 2030, reaching net-zero emissions by 2050. Meeting those emissions targets will require dramatic reductions in global CO2 emissions combined with the active removal of CO2 from the atmosphere.
Improve Health, Benefit Society
Efforts to reduce greenhouse gas emissions will have additional benefits. For example, fossil fuel emissions are responsible for the majority of air pollution, which kills millions globally each year. This transition also presents an opportunity to build a more competitive U.S. economy, increase the availability of high-quality jobs, and address social injustices that permeate our current energy system.

Emissions Reduction Strategies

Avoiding the worst impacts of climate change requires a portfolio of options. The primary focus should be on implementing technologies to reduce greenhouse gas emissions, particularly CO2, complemented by efforts to remove and reliably sequester carbon from the atmosphere and to curb emissions of other greenhouse gases.

As the first line of defense against climate change, the world is transforming its energy system from one dominated by fossil fuel combustion to one with net-zero emissions of carbon dioxide. Accelerating Decarbonization of the U.S. Energy System (2021) identifies technology goals, socioeconomic goals, and policy options and federal actions that would put the United States on a fair and equitable path to net-zero in 2050.

Technology Goals

Achieving a net-zero emissions energy system will require that the United States begin working on five technology goals:

As of 2020, U.S. electricity generation was composed of about 60% fossil fuels, 20% nuclear, and 20% hydropower and other renewables. There are many sources of energy that produce little or no CO2 emissions, including solar, wind, geothermal, and hydropower.

To meet the goal of net-zero by 2050, the United States should double the share of electricity generated by non-carbon-emitting sources to at least 75% by 2030, which will require:

  • Record-setting deployment of solar and wind technologies
  • Scaling back coal and some gas-fired power plants,
  • Preserving operating nuclear plants and hydroelectric facilities where possible.

Reducing emissions will require that existing and planned transportation, building, and industrial infrastructure be converted to use electricity from low-carbon sources where possible.  Meeting net-zero targets by 2050 will require that by 2030 the United States:

  • Aim for 50% of all new vehicle sales to be zero emissions vehicles.
  • Replace 20% or more of fossil fuel furnaces with electric heat pumps in buildings.
  • Require that new building construction is all electric except in the coldest climate zones.
  • Begin the transition to low-carbon heat sources for industrial process that cannot be fully electrified.

Technology advances such as LED lighting and energy efficient appliances have helped high-income countries substantially reduce energy use per capita and per unit of economic output.  Efficiency gains to date, however, are not enough.  Meeting net-zero targets by 2050 will require that by 2030 the United States:

  • Reduce total energy use in new buildings by 50%.
  • Lower energy used for space conditioning and plug-in devices in existing buildings each year to achieve a 30% reduction by the end of the decade.
  • Increase goals for industrial energy productivity (dollars of economic output per energy consumed) each year.

Achieving the transition to clean electric power generation requires development of the infrastructure to support it.  By 2030, the United States should:

  • Increase overall electrical transmission capacity by approximately 40% to better distribute high quality and low-cost wind and solar power from where it is generated to where it can be used.
  • Accelerate the build-out of the electric vehicle recharging network.

The nation should triple federal investment in clean energy research, development, and demonstration (RD&D) in order to provide new technology options, reduce costs for existing options, and better understand how to manage a socially-just energy transition.

Socioeconomic Goals

The transition to a carbon-neutral energy system has the potential to revitalize the U.S. economy, create 1-2 million jobs over the next decade, and address inequities in our current energy system. Policies to enable the transition to net-zero emissions should be designed to advance four critical socioeconomic goals to ensure an equitable transition:

Global demand for clean energy and climate mitigation solutions will reach trillions of dollars over the coming decades, creating an opportunity to revitalize U.S. manufacturing, construction, and commercial sectors, while providing a net increase in jobs paying higher wages than the national average.

U.S. policies should promote equitable access to the benefits of clean energy systems, including reliable and affordable energy, new training and employment opportunities, and opportunities for wealth creation. Policies for the net-zero emissions economy should also work to eliminate inequities in the current energy system that disadvantage historically marginalized and low-income populations.

There will be a need to identify and mitigate job losses and other impacts on labor sectors and communities negatively impacted by the transition of the U.S. economy to net-zero emissions. U.S. policies should promote fair access to new long-term employment opportunities and provide financial and other support to communities that might otherwise be harmed by the transition.

A cost-effective strategy (balanced by equity considerations) will reduce carbon emissions, strengthen the U.S. economy, and avoid undue burdens on American households and businesses during the transition to a net-zero emissions economy.

Recommended U.S. Policies

The following policy changes would help support the U.S. transition to a new energy system.

  • Setting an official U.S. emissions budget for carbon dioxide and other greenhouse gases to support the goal of reaching net-zero emissions by 2050
  • An economy-wide price on carbon, in addition to other policies focusing on particular sectors
  • A new National Transition Task Force to evaluate how best to support labor sectors and communities that will be affected by the energy transition
  • A new Office of Equitable Energy Transitions within the White House to establish criteria, measure, and report back on net-zero transition impacts and equity considerations
  • A new independent National Transition Corporation to provide support and opportunities for displaced workers and affected communities
  • A new Green Bank, capitalized initially at $30 billion and rising to $60 billion by 2030, to ensure the required capital is available for the net-zero transition and to mobilize greater private investment
  • A comprehensive education and training initiative to develop the workforce required for the net-zero transition, to fuel future innovation, and to provide new high-quality jobs
  • Setting national standards for clean electricity and electrification and efficiency standards for vehicles, appliances, and buildings

Additional Resources
Explore more about the policy options in this interactive tool.

Reducing emissions is a primary goal, but deployment of negative emissions technologies (NETs) will also be needed.  Meeting the goal of net-zero by 2050 will likely require the removal globally of about 10 Gt/y CO2 by 2050 and 20 Gt/y by 2100.  Negative Emissions Technologies and Reliable Sequestration: A Research Agenda (2019) assessed the costs, potential for carbon removal, and barriers to overcome for several available and emerging technologies.

Assessed Potential and Limiting Factors of NET Technologies

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Terrestrial Carbon Removal and Sequestration Biomass Energy with Carbon Capture and Sequestration Carbon Mineralization Coastal Blue Carbon Direct Air Capture

View this table for details on costs, CO2 removal rate, and limiting factors for each technology assessed.

NETs Ready to Deploy

Terrestrial carbon removal strategies and BECCS could be scaled up to capture and store substantial amounts of carbon: ~1 Gt CO2/yr in the United States and ~10 Gt CO2/yr globally. However, unprecedented rates of adoption of agricultural soil conservation practices, forestry management practices, and waste biomass capture would be needed. Practically, about half the full potential is achievable.

NETs with High Potential but High Costs and Uncertainty

Direct air capture or carbon mineralization could be revolutionary, because of the large potential capacity for CO2 removal. The primary impediment to direct air capture is high cost.  Carbon mineralization needs to be better understood.

Recommended Research on NETs

A substantial research initiative is needed that is focused on the following goals:

  • Improve existing NETs by increasing their capacity and reducing their negative impacts and costs;
  • Make rapid progress on direct air capture and carbon mineralization technologies;
  • Advance NET-enabling research on biofuels and CO2 sequestration that should be undertaken anyway as part of an emissions mitigation research portfolio.

The ocean covers 70% of the Earth’s surface and provides much of the global capacity for natural carbon sequestration. It currently holds roughly 50 times as much inorganic carbon as the preindustrial atmosphere.

The ocean’s natural capacity to store carbon could be enhanced with strategies that act to remove CO2 from the atmosphere and upper ocean and store it in ocean reservoirs, such as marine plants and geologic, or geological reservoirs for some period of time.

A Research Strategy for Ocean-Based Carbon Dioxide Removal and Sequestration (2021) develops a research agenda to assess the benefits, risks, and potential for responsible scale up of six specific ecosystem-based and technological ocean-based CDR approaches.

Ocean-based Carbon Dioxide Removal (CDR) Strategies

The report assessed six carbon dioxide removal (CDR) and sequestration strategies conducted in coastal and open ocean waters. Each approach was evaluated based on its existing knowledge base, potential efficacy, durability, scale, project costs, monitoring and verification, viability and barriers, and governance and social dimensions.

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View this table to compare the six ocean CDR technologies.

OCEAN-CDR RESEARCH PRIORITIES

At present, society and policymakers lack sufficient knowledge to fully evaluate ocean CDR outcomes and weigh the trade-offs with other climate response approaches, and with environmental and sustainable development goals. A research program should be implemented to address current knowledge gaps. The best approach will involve a diversified research investment strategy that includes both cross-cutting, common components and coordination across multiple individual CDR approaches in parallel.

Amongst the biotic approaches, research on ocean iron fertilization and seaweed cultivation offer the greatest opportunities for evaluating the viability of possible biotic ocean CDR approaches; research on the potential CO2 removal and sequestration permanence for ecosystem recovery would also be beneficial in the context of ongoing marine conservation efforts.

Amongst the abiotic approaches, research on ocean alkalinity enhancement, including electrochemical alkalinity enhancement, have priority over electrochemical approaches that only seek to achieve carbon dioxide removal from seawater (also known as carbon dioxide stripping).

Cross-Cutting Research Priorities

 

Estimated Budget

Duration (yr)

Total

Model international governance framework for ocean CDR research

$2-3M/yr

2-4yrs

$4-12M

Application of domestic laws to ocean CDR research

$1M/yr

1-2yrs

$1-2M

Assessment of need for domestic legal framework specific to ocean CDR


Development of domestic legal framework specific to ocean CDR 

$1M/yr

2-4yrs

$2-4M

Mixed-methods, multi-sited research to understand community priorities and assessment of benefits and risks for ocean CDR as a strategy

$5M/yr

 4yrs

 $20M

Interactions and tradeoffs between ocean CDR, terrestrial CDR, adaptation, and mitigation, including the potential of mitigation deterrence

$2M/yr

 4yrs

 $8M

Cross-sectoral research analyzing food system, energy, Sustainable Development Goals, and other systems in their interaction with ocean CDR approaches

$1M/yr

4yrs

$4M

Capacity-building research fellowship for diverse early-career scholars in ocean CDR

$1.5M/yr

2yrs

$3M

Transparent, publicly accessible system for monitoring impacts from projects

$0.25M/yr

4yrs

$1M

Research on how user communities (companies buying and selling CDR, NGOs, practitioners, policymakers) view and use monitoring data, including certification

$0.5M/yr

4yrs

$2M

Analysis of policy mechanisms and innovation pathways, including on the economics of scale up

$1-2M/yr

2yrs

$2-4M

Development of standardized environmental monitoring and carbon accounting methods for ocean CDR 

$0.2M/yr

3yrs

$0.6M

Development of a coordinated research infrastructure to promote transparent research

$2M/yr

3-4yrs

$6-8M

Development of a publicly accessible data management strategy for ocean CDR research

$2-3M/yr

2yrs

$4-6M 

Development of a coordinated plan for science communication and public engagement of ocean CDR research in the context of decarbonization and climate response

$5M/yr

10yrs

$50M

Development of a Common Code of Conduct for ocean CDR research

$1M/yr

2yrs

$2M

Total Estimated Research Budget
(Assumes all 6 CDR approaches moving ahead)

~$30M/yr

2-10 yrs

~$125M

Research Needed to Advance Ocean CDR Approaches

 

Estimated Budget

Duration (yr)

Total Budget

Carbon sequestration delivery and bioavailability

$5M/yr

5yrs

~$25M

Tracking carbon sequestration

$3M/yr

5yrs

~$15M

In field experiments- >100 tons Fe
  and >1000 km^2 initial patch size followed over annual cycles

$25M/yr

10yrs

~$250M

Monitoring carbon and ecological shifts

$10M/yr

10yrs

~$100M

Experimental planning and extrapolation to
  global scales

$5M/yr

10yrs

~$50M

Total Estimated Research Budget 

$48M/yr

5-10 yrs

$445M

Estimated Budget of Research Priorities

$33M/yr

5-10 yrs

$290M

 

Estimated Budget

Duration (yr)

Total Budget

Technological readiness: Limited and controlled open ocean trials to determine durability and operability of artificial upwelling technologies 
(~ 100 pumps tested in various conditions)

$5M/yr

5yrs

$25M

Feasibility Studies

$1M/yr

1yr

$1M

Tracking carbon sequestration

$3M/yr

5yrs

$15M 

Modeling of carbon sequestration based upon achievable upwelling velocities and known stoichiometry of deep water sources. Parallel mesocosm and laboratory experiments to assess potential biological responses to deep water of varying sources 

$5M/yr

5yrs

$25M   

Planning and implementation of demonstration scale in situ experimentation (> 1 year, >1000 km) in region sited based input from modeling and preliminary experiments  

$25M/yr

10yrs

$250M   

Monitoring carbon and ecological shifts

$10M/yr

10yrs

$100M 

Experimental planning and extrapolation to global scales
(early for planning and later for impact assessments)

$5M/yr

10yrs

$50M

Total Estimated Research Budget

~$53/yr

5-10 yrs

$466M

Estimated Budget of Research Priorities

$5M/yr

5-10 yrs

$25M

 

Estimated Budget

Duration (yr)

Total Budget

Technologies for efficient large-scale farming
  and harvesting of seaweed biomass

$15M/yr

10yrs

$150 M
(based on present MARINER funding levels)

Engineering studies focused on the conveying of harvested biomass to durable oceanic reservoir with minimal losses of   carbon 

$2M/yr

10yrs

$20 M

Assessment of long-term fates of seaweed biomass & byproducts

$5M/yr

5yrs

$25M

Implement & deploy a demonstration-scale
  seaweed cultivation & sequestration system

$10M/yr

10yrs

$100M

Validate & monitor the CDR performance of a
  demonstration-scale seaweed cultivation & sequestration system

$5M/yr

10yrs

$50M

Evaluate the environmental impacts of
  large-scale seaweed farming and sequestration

$4M/yr

10yrs 

$40M

Total Estimated Research Budget

$41M/yr

5-10 yrs

$385M

Estimated Budget of Research Priorities

$26M/yr

5 years

$235M

 

Estimated Budget

Duration (yr)

Total Budget

Restoration ecology and carbon

$8M/yr

5yrs

$40M 

Marine protected areas: Do ecosystem-level protection and restoration scale for marine CDR?

$8M/yr

10yrs

 $80M

Macroalgae: Carbon measurements, global range, and levers of protection

$5M/yr

10yrs

 $50M

Benthic communities: disturbance and restoration

$5M/yr

5yrs

 $25M

Marine animals and CO2 removal

$5M/yr

10yrs

 $50M

Animal nutrient-cycling 

$5M/yr

5yrs

 $25M

Commercial fisheries and marine carbon

$5M/yr

5yrs

 $25M

Total Estimated Research Budget

$41M/yr

5-10 yrs

$295M

Estimated Budget of Research Priorities

$26M/yr

5-10 yrs

$220M

 

Estimated Budget

Duration (yr)

Total Budget

Research and development to explore and improve the technical feasibility/and readiness level of ocean alkalinity enhancement approaches (including the development of pilot scale facilities)

$10M/yr

5yrs

$50M

Laboratory and mesocosm experiments to explore impacts on physiology and functionality of organisms/communities

$10M/yr

5yrs

$50M

Field experiments

$15M/yr

5-10yrs

$75-150 M

Research into the development of appropriate monitoring and accounting schemes, covering CDR potential and possible side effects.    

$10

5-10yrs

$50-100 M

Total Estimated Research Budget

$45M/yr

5-10 yrs

$180-350M

Estimated Budget of Research Priorities

$25M/yr

5-10 yrs

$125-200M

 

Estimated Budget

Duration (yr)

Total Budget

Demonstration projects including CDR verification and environmental monitoring

$30M/yr

5yrs

$150M

Development and assessment of novel electrode materials

$10M/yr

5yrs

$50M

Assessment of environmental impact and acid management strategies

$7.5M/yr

10yrs

$75M

Coupling whole rock dissolution to electrochemical reactors and systems

$7.5M/yr

10yrs

$75M

Development of hybrid approaches

$7.5M/yr

10yrs

$75M

Resource mapping and pathway assessment

$10M/yr

5yrs

$50M

Total Estimated Research Budget

$72.5M/yr

5-10 yrs

$475M

Estimated Budget of Research Priorities

$55M/yr

5-10 yrs

$350M

While reducing carbon dioxide emissions is a primary goal, much can be done to reduce other greenhouse gases that contribute to climate change. Methane, nitrous oxide, and some industrial gases (e.g., hydrofluorocarbons) comprise about 18 percent of U.S. greenhouse gas emissions in terms of CO2 equivalents.

Sources of Methane
Human activities that emit methane (the primary component of natural gas) include petroleum and natural gas systems, cattle and manure management, landfills, and coal mines. Levels of atmospheric methane have risen steadily over the past century and are unprecedented over the past 2,000 years as measured in ice cores. Methane is second only to carbon dioxide in its contribution to rising global average temperatures.

Sources of Nitrous Oxide
Human activities that emit nitrous oxide are primarily from agriculture and also from fossil fuel combustion, and industrial processing. Levels of nitrous oxide in the atmosphere have risen steadily since the Industrial Revolution and more sharply over the past four decades.

Reducing and Tracking Methane Emissions

Methane is not as long-lived in the atmosphere as carbon dioxide, but it is a more powerful warming agent.  Reducing methane emissions could help prevent the worst impacts of climate change.  Efforts to reduce methane emissions, along with reductions in black carbon emissions, could help reduce global mean warming in the near term, with additional benefits for air quality and agricultural productivity.

Tracking atmospheric methane levels and methane emissions is essential for informing efforts to reduce it.  However, tracking is difficult given the many human and natural sources of methane.  Improving Characterization of Anthropogenic Methane Emissions in the United States (2018) recommends strengthening measurement, monitoring, and inventories of methane emissions and launching a nationwide research effort to address knowledge gaps.

Reducing Emissions from Agriculture

Agriculture is a large source of non-CO2  greenhouse gases. Livestock farming may be responsible for as much as 14.5 percent of all human-induced greenhouse gas emissions (including CO2).  Methane is produced when livestock digest their food and also is emitted in large quantities from rice paddies.  Nitrous oxide arises from applications of fertilizer. 

Environmental Engineering for the 21st Century: Addressing Grand Challenges (2020) identifies several pathways to reducing agricultural emissions, including:

  • Feeding livestock easier-to-digest foods and strategically managing livestock waste through proper storage, reuse as fertilizer, and recovery of methane
  • Precision agriculture techniques to help farmers minimize fertilizer use and reduce nitrous oxide emissions. 
  • Shifting dietary patterns to de-emphasize animal-based protein, particularly beef.
  • Reducing food waste, which is currently estimated at one-third of all food produced.


Evidence of Climate Change

It is now more certain than ever, based on many lines of evidence, that humans are changing Earth’s climate. Climate Change: Evidence and Causes (updated 2020), a booklet produced by the National Academies and The Royal Society, lays out the evidence that human activities, especially the burning of fossil fuels, are responsible for much of the warming and related changes observed around the world.  The booklet includes a section on Basics of Climate Change for those who want to learn more.

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Earth’s Average Surface Temperatures are Increasing

Since 1900, Earth’s average surface air temperature has increased by about 1 °C (1.8 °F), with over half of the increase occurring since the mid-1970s. A wide range of other observations such as reductions in Arctic sea ice, reduced snowpack, and ocean warming, along with indications from the natural world, such as poleward migrations of some species, provide incontrovertible evidence of planetary-scale warming.


Figure 1a: Annual Global Temperature 1850-2019

Figure 1b: Evidence that Earth's Climate is Changing

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Levels of Atmospheric Greenhouse Gases are Increasing

The average concentration of atmospheric CO2 measured at the Mauna Loa Observatory in Hawaii has risen from 316 parts per million (ppm) in 1959 (the first full year of data available) to more than 411 ppm in 2019.

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Human Activities are Changing the Climate

Rigorous analysis of all data and lines of evidence shows that most of the observed global warming over the past 50 years or so cannot be explained by natural causes and instead requires a significant role for the influence of human activities.

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Projected Warming Given Current Emissions

If emissions continue on their present trajectory, without either technological or regulatory abatement, then warming of 2.6 to 4.8 °C (4.7 to 8.6 °F) in addition to that which has already occurred would be expected during the 21st century.

Connect with National Academies Climate Work


Climate Crisis Demands ‘Urgent and Ambitious’ Response

The presidents of the National Academies said in an October 29, 2021 statement that COP26 presents a historic global opportunity to agree on emissions reduction targets to avoid the most intolerable impacts of climate change.

The National Academies conducts a wide range of ongoing activities related to climate change, including studies, events, roundtables, and initiatives.   To learn more, visit our Climate Resources website and subscribe to the National Academies climate email list to stay apprised of news and opportunities to participate.

Reports Referenced in this Resource:

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