On his first day in office last week, President Trump began to redirect American energy and environmental policy with a series of executive orders that could have long-term effects on both the climate and American businesses.

One of these January 20 orders — Unleashing American Energy — takes aim at the Environmental Protection Agency’s ability to regulate climate-warming greenhouse gases. It directs the EPA to submit recommendations on the “legality and applicability” of the agency’s 2009 endangerment finding — the science-based determination, made under the Clean Air Act, that greenhouse gases endanger public health and welfare. The endangerment finding underpins the EPA’s climate regulations.

The obscurely worded directive appears to suggest that the EPA should consider rescinding the endangerment finding, which the first Trump administration contemplated but ultimately declined to do. Rescinding the finding now would require the agency to rebut a voluminous scientific record attesting to the serious harms to public health already occurring and likely to worsen with rising temperatures. That record has only grown stronger since 2009 when the Obama administration first made the endangerment finding in the aftermath of the Supreme Court’s Massachusetts v. EPA decision, when the Court ruled that greenhouse gases are pollutants under the Clean Air Act and that the George W. Bush EPA had erred in refusing to decide, based on the science, whether these gases posed an endangerment.

But it would be an uphill battle to convince federal judges in 2025, even conservative ones, that the scientific record on climate change is wrong.

Read the full article by Jody Freeman and Carrie Jenks at the Harvard Climate Blog.