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United States Sectors

What is The United Statesʼ pathway to limit global warming to 1.5°C?

How to citeLast update: January 2023

The transport sector’s CO₂ emissions increased rapidly from the early 1990s to the early 2000s before levelling off and dropping following the 2008 financial crisis. Emissions had begun to rebound but dropped again during the COVID-19 pandemic. In 2017, transport emissions were the second largest source of energy-related emissions and accounted for 28% of total emissions excluding LULUCF. The current transport energy mix is dominated by oil with small shares of biomass and fossil gas.

1.5°C pathways analysed here indicate that transport CO₂ emissions would need to drop by 44–65% below 2019 levels by 2030, and by 96–98% by 2050. This would be enabled by decreasing energy demand coupled with electrification and fuel switching to hydrogen and biofuels. While the pathways show the US only reaching 5–6% electrification by 2030, this is very likely an underestimation of the potential for electrifying transport in the US.14 Between 2020 and 2021, the EV share of new light-duty vehicles nearly doubled, reaching 4.4% in 2021.

The Biden administration has announced targets to have half of all new light-duty vehicles and 30% of new medium- and heavy-duty vehicles sold in the US to be zero-emission vehicles by 2030.6,7 These targets are supported by provisions in the Inflation Reduction Act (IRA) of 2022, such as EV tax credits, installation of charging infrastructure and domestic supply chain development.3 Analysis by BNEF expects IRA provisions to increase the US EV fleet by 20% above previous projections by 2030. California and Massachusetts have set even more ambitious EV targets with other states expected to join.15

Missing from the IRA, however, were significant investments in passenger rail that had been in the failed Build Back Better bill that would help shift the US away from its dependence on cars.16

1 The United States of America. The United States of America – Nationally Determined Contribution. 2021.

2 Climate Action Tracker & New Climate Institute. USA | Climate Action Tracker. 2022.

3 Rep. Yarmuth, J. A. H.R.5376 – Inflation Reduction Act of 2022. (117th Congress, 2022).

4 Climate Action Tracker. To show climate leadership, US 2030 target should be at least 57-63% – Mar 2021. (2021).

5 U.S. Department of State. The Long-Term Strategy of the United States: Pathways to Net-Zero Greenhouse Gas Emissions by 2050. 2021.

6 Shepardson, D. U.S. aims for zero-emissions heavy-duty vehicles by 2040. Reuters. 2022.

7 The White House. Executive Order on Strengthening American Leadership in Clean Cars and Trucks. The White House. 2021.

8 Biden for President. The Biden plan to build a modern, sustainable infrastructure and an equitable clean energy future. (2020).

9 Larsen, J. et al. A Turning Point for US Climate Progress: Assessing the Climate and Clean Energy Provisions in the Inflation Reduction Act. 2022.

10 NCSL. State Renewable Portfolio Standards and Goals. NCSL. 2021.

11 Barbose, G. L. U.S. Renewables Portfolio Standards 2021 Status Update: Early Release. 2021.

12 Denholm, P. et al. Examining Supply-Side Options to Achieve 100% Clean Electricity by 2035. 2022.

13 ICAP. Welcome to the ICAP ETS Map. International Carbon Action Partnership. 2022.

14 Cui, H. & Hall, D. Annual update on the global transition to electric vehicles: 2021. ICCT. Preprint at (2022).

15 E360. U.S. Inflation Reduction Act to Boost EV Adoption by 20 Percent, Analysis Finds. Yale Environment 360. 2022.

16 Wilson, K. Advocates: Cutting High Speed Rail Out of Climate Bill Was a Mistake. Streetsblog USA. 2022.

17 While global cost-effective pathways assessed by the IPCC Special Report 1.5°C provide useful guidance for an upper-limit of emissions trajectories for developed countries, they underestimate the feasible space for such countries to reach net zero earlier. The current generation of models tend to depend strongly on land-use sinks outside of currently developed countries and include fossil fuel use well beyond the time at which these could be phased out, compared to what is understood from bottom-up approaches. The scientific teams which provide these global pathways constantly improve the technologies represented in their models – and novel CDR technologies are now being included in new studies focused on deep mitigation scenarios meeting the Paris Agreement. A wide assessment database of these new scenarios is not yet available; thus, we rely on available scenarios which focus particularly on BECCS as a net-negative emission technology. Accordingly, we do not yet consider land-sector emissions (LULUCF) and other CDR approaches which developed countries will need to implement in order to counterbalance their remaining emissions and reach net zero GHG are not considered here due to data availability.

18 In some of the analysed pathways, the energy sector assumes already a certain amount of carbon dioxide removal technologies, in this case bioenergy carbon capture and storage (BECCS).

The United Statesʼ energy mix in the transport sector

petajoule per year

SSP1 Low CDR reliance
201920302040205020 000
SSP1 High CDR reliance
201920302040205020 000
Low energy demand
201920302040205020 000
High energy demand - Low CDR reliance
201920302040205020 000
  • Natural gas
  • Coal
  • Oil and e-fuels
  • Biofuel
  • Biogas
  • Biomass
  • Hydrogen
  • Electricity
  • Heat

The United Statesʼ transport sector direct CO₂ emissions (of energy demand)


5001 0001 5002 00019902010203020502070
  • Historical emissions
  • SSP1 High CDR reliance
  • SSP1 Low CDR reliance
  • High energy demand - Low CDR reliance
  • Low energy demand

1.5°C compatible transport sector benchmarks

Direct CO₂ emissions and shares of electricity, biofuels and hydrogen in the transport final energy demand from illustrative 1.5°C pathways for The United States

Decarbonised transport sector by
Direct CO₂ emissions
1 757
619 to 987
151 to 162
28 to 74
2044 to 2054
Relative to reference year in %
−65 to −44%
−98 to −96%
Share of electricity
5 to 6
25 to 28
38 to 59
Share of biofuels
21 to 25
27 to 52
17 to 51
Share of hydrogen
1 to 15
8 to 50
12 to 55