From his lab in Toulouse, France, Benjamin Sanderson models the range of extreme risks to humans from climate change, research he hopes can inform policymakers planning for worsening wildfires and floods. It is the kind of work he once performed in the United States — and hopes to again soon.

Sanderson is among dozens of U.S.-based climate scientists who shifted their research to France, or sought refuge in academia or in left-leaning states like California after Republican Donald Trump was elected in 2016. They worried his administration’s distrust of science would impact their ability to finance and advance their work.

Now, with the presidential election looming — and Democrat Joe Biden ahead in the polls and promising to prioritize the role of science in policymaking — some of these researchers hope for a return to the days when the United States was viewed as the best place on earth to do their jobs.