As Donald Trump prepared to become the 45th president of the United States, scientists from around the country marked the day by taking to Twitter.

During the election campaign, Trump repeatedly remarked on issues of science, often incorrectly. He claimed that climate change is a hoax invented by the Chinese. He also said that he would pull out of the Paris climate agreement, which aims to cut CO2 emissions in an effort to reduce the pace at which the planet is warming.

His cabinet nominations have also concerned scientists, with Rick Perry poised to head the department of energy, which, in 2011, he said he wanted to do eliminate (he has since apologized and said he's had a change of heart).

Scott Pruitt, the Trump nominee to head the U.S. Environmental Protection Agency (EPA), has no scientific training. Trump has said he'd like to eliminate the agency and gut environmental policies.

Scientists have flooded Twitter with tweets about science policy and scientific research.