Kelly Ramirez was distraught as she watched the US presidential election results come in on 9 November. The soil microbial ecologist at the Netherlands Institute of Ecology in Wageningen started texting friends — all women scientists — back in the United States. They were appalled at the eventual winner, Republican Donald Trump, for what they saw as his cavalier attitude towards facts and discriminatory actions against groups such as Muslims, Latinos and women.

Although few of the scientists had any experience with political activism, they felt an urge to respond to Trump’s victory. “By Thursday I said, ‘enough crying about it: let’s do something,’” Ramirez says.

The result was a pledge signed by more than 11,000 women scientists in which they commit “to build a more inclusive society and scientific enterprise”. It is just one manifestation of the scientific community’s unusually active response to the incoming president. Around the world, individual researchers and representatives of scientific societies are signing letters of protest or advice, offering to counsel Trump’s transition team and ramping up efforts to communicate the value of science to the public.

“It is an encouraging sign that there is a ‘Trump effect’ on scientists’ willingness to stand up for science,” says Geoffrey Supran, a climate scientist at Harvard University and the Massachusetts Institute of Technology, both in Cambridge. Supran, who has a history of climate activism, helped to organize a letter to Trump on climate policy that was signed by more than 800 Earth scientists.