When asked why he changed his mind, Bridenstine told The Washington Post, "I heard a lot of experts, and I read a lot. I came to the conclusion myself that carbon dioxide is a greenhouse gas, that we've put a lot of it into the atmosphere, and therefore we have contributed to the global warming that we've seen."

The scientists, from the UK, Canada, Australia and other Commonwealth countries, warn that stronger measures are needed to keep global warming under 2 degrees.

French President Emmanuel Macron will award U.S. climate scientists with grants to conduct research in France for the remainder of President Trump’s current presidential term.