Watson Institute for International and Public Affairs
Climate Solutions Lab

Is the United States Underplaying the Threat of Climate Change? Reevaluating the National Climate Assessment

November 18, 2021

Jeff Colgan profile image

Jeff Colgan and co-author Alexander Gard-Murray recently published a Climate Solutions White Paper focusing on how the summary findings directed at policymakers and technical audiences might be improved, and how a new publicfacing "Summary for American Families" could help the NCA communicate its results more broadly. 

The National Climate Assessment (NCA) is the U.S. government's official report on the science of climate change. Published in 2018, the Fourth NCA synthesizes a vast quantity of complex data gathered from 13 federal agencies and departments. Its authors should be proud of the massive scientific coordination it represents. But as the Fifth NCA is prepared for publication in 2023, we argue there is room to improve. 

For all the NCA’s comprehensiveness, its Summary Findings don’t frame climate threats forcefully enough. The underlying data can often be found somewhere in the full NCA, but the Summary does not adequately convey the implications for American lives. It contains few numbers, making it hard for readers to gauge scale and urgency. Impacts are discussed in high-level terms that don’t always capture the basic ways in which American lives will be fundamentally altered. And it doesn’t explain how even small increase could have catastrophic effects, especially if they trigger “tipping points” in the Earth’s climate.

It's one thing to write broadly about increased temperatures. It’s another to show how many days will be fatal for humans outdoors because it will be too hot and humid to sweat; to specify how many American jobs will be lost to drought and heat exhaustion; to forecast how many American homes will destroyed by heat wavedriven fires; to tally the American childhoods radically reined in and the American lives cut short. These examples illustrate the multiple impacts of just one aspect of climate change—increased temperature—and there are many others.  In every area the 4 report covers, from flooding and disease to infrastructure and agriculture, each highlevel trend has intensely personal impacts that deserve to be communicated.

The NCA does not need to champion particular policy responses. But it does need to explain, in clear and relevant terms, what’s at stake if we fail to act.