(CN) – In 2009, the Environmental Protection Agency under President Barack Obama announced that greenhouse gasses endangered public health – a finding that formed the legal basis for fighting climate change under the Clean Air Act. Nearly a decade later, the peril from climate change is clearer than ever. And scientists are fighting to justify the EPA’s endangerment finding in a new study published Thursday in the journal Science.

The Supreme Court found in the 2007 Massachusetts v. EPA that, under the Clean Air Act, the EPA must regulate greenhouse gases once it has determined the emissions endanger the health and welfare of current and future generations. The EPA issued its first such finding two years later, based on research by the U.S. Global Change Research Program, Intergovernmental Panel on Climate Change, and the U.S. National Research Council.
Since then, the evidence has only strengthened. Yet the political will to make changes has shriveled, according to Phil Duffy, the study’s lead author and former science adviser to Obama.
“Harms from greenhouse gases and manifestations from climate change are much more real now than they were nine years ago,” Duffy said. “Nine years ago they were here, but they were more in the future with potential harms. Now they are much more immediate – things like extreme weather and wildfire, which have been very vigorously tied to climate change and are much more prominent now.”
That, and the potential for Trump-era EPA administrators to try to toss out the endangerment finding, motivated Duffy to round up experts in each category of danger to review science produced after 2009.
“There have been rumblings by people inside the Trump administration, and also people outside it who they listen to, that we should revisit or overturn the endangerment finding,” Duffy said. “If there were an attempt to overturn the endangerment finding, I imagine there would be litigation, and then this would be useful – a peer-reviewed study saying evidence is even stronger than in 2009, and it was already very strong in 2009.”
Former EPA administrator Scott Pruitt repeatedly suggested repealing the endangerment finding, according to news reports. Pruitt resigned in July amid over a dozen investigations into possible misuse of office. Acting EPA Administrator Andrew Wheeler told the Washington Post shortly after he took over leadership at the agency that he considered the endangerment finding to be settled law. But Wheeler, a former coal lobbyist, has also vowed to carry out President Donald Trump’s pro-fossil fuel agenda.
“It’s a strange time now because there have been, in the last month or two, a series of high-level science reports – one from the U.N. Intergovernmental Panel on Climate Change and the National Climate Assessment – both were very stark, and both pointed out the immediacy of the impacts and the urgent need for action,” Duffy said. “So the science is very clearly pointing in one direction and yet the policies, the U.S. policies at least, are going in the exact opposite direction.”
Duffy’s results are grim.
“What has happened now is land ice sheets are melting faster than we thought,” he said. “That means sea level rise is going to be worse than we thought and meanwhile in the last nine years, we haven’t really done anything to stop it.”
The 2009 endangerment finding was based on the peril caused by greenhouse gases in seven categories: air quality; food production and agriculture; forestry; water resources; sea level rise and coastal areas; energy, infrastructure and settlements; and ecosystems and wildlife.
This time around, Duffy and the panel of 16 scientists who co-authored the study said it was necessary to add sections for ocean acidification, violence and social instability, national security and economic well-being.