UCS Delivers Letter Signed by Hundreds of Scientists Supporting EPA’s Proposed Update to Calculating Costs of Climate Change

The Union of Concerned Scientists (UCS) today delivered a letter to the U.S. Environmental Protection Agency (EPA) in support of their draft report on the social cost of greenhouse gases, which includes provisions to strengthen the estimates U.S. government agencies use to calculate the economic damages associated with the release of each ton of heat-trapping emissions. Under this proposal, the central value of the 2020 estimate of the damage caused by a metric ton of carbon dioxide—commonly referred to as the “social cost of carbon”—would increase from $51 to $190. The proposal also updates the social cost of methane and nitrous oxide gases. The letter was signed by approximately 400 experts, including climate scientists Drs. Andrea Dutton, Michael Mann, and Don Wuebbles, and economists Drs. Linda Bilmes, Eric Maskin, and Gary Yohe.

“This update by the EPA more closely reflects the latest climate science and economics to help ensure government agencies are appropriately accounting for the damages caused by U.S. global warming emissions, and the significant benefits from cutting them,” said Dr. Rachel Cleetus, the policy director and lead economist in the Climate and Energy Program at UCS. “The mounting costs of the climate crisis are already evident in the United States and around the world and will only continue to worsen as the planet warms—a reality that must be accurately accounted for in our nation’s policies. While this update is a welcome and significant step, it’s still conservative in estimating the true costs of climate change, as it doesn’t fully factor in impacts to human health, livelihoods, ecosystems, loss of cultural heritage, the significance of surpassing irreversible climate thresholds, or ways in which pre-existing socioeconomic inequities could be further exacerbated by global warming.”

The letter emphasizes especially strong support for these provisions included in EPA’s draft update:

• Better incorporation of a broader range of climate impacts and associated costs to account for continued advances in peer-reviewed scientific and economic literature.
• Reducing the discount rate applied to future damages, as a way of helping to ensure that costs and benefits to current and future generations are better accounted for in today’s policies and actions.
• Accounting for global damages in recognition of the fact that heat-trapping emissions are global pollutants, meaning the choices one country makes could affect the climate impacts experienced by other nations.
  Letter signatories also urge EPA and the Biden administration to continue to invest in regular, systematic updates to these vital estimates based on advances in science and economics, as well as the perspectives of a diverse group of interdisciplinary experts and the communities being hit hardest by the climate crisis.

The following UCS experts, who are also letter signatories, are available to speak about the significance of this proposed change.

• Dr. Rachel Cleetus, the policy director and lead economist for the climate and energy program at UCS. She is based in Cambridge, Massachusetts. Click here to view her full biography.
• Dr. Brenda Ekwurzel, the director of climate science and senior climate scientist at UCS. She is a co-author of the Fourth National Climate Assessment. Dr. Ekwurzel is based in Washington, D.C. Click here to view her full biography.

If you would like to talk to an expert, please contact UCS Climate and Energy Media Manager Ashley Siefert Nunes.