The singer recorded a video message, with "The Office" actor Rainn Wilson, explorer Levison Wood and Robert Irwin, son of the late Australian conservationist Steve Irwin, also lending their voices to the project in conjunction with Britain's University of Exeter.
The global climate summit, hosted by British Prime Minister Boris Johnson, kicks off in Glasgow on Oct 31.
"This year our leaders are deciding the global actions required on the environment climate emergency in a critical decade for our planet," Eilish said. "We must stand together and speak up to save our planet, not just for us, but for our future generations, and we need urgent, urgent action now and to work together as one.
Britain has cast the summit as the last big chance for countries to commit to steps to slow rising temperatures.
"Courage. That's what our world’s leaders need more than anything. The decisions that they make about the climate crisis in the next decade are the most important decisions in our planet’s history," Wilson said.
Arctic Basecamp was founded by Gail Whiteman, a social scientist who studies how decision makers make sense of environmental threats such as climate change. The group has set up a tent camp for scientists at the World Economic Forum in Davos and will be attending the COP26 summit.
"This is a crisis and the Arctic is sounding the alarm. It is time that world leaders come together to create real change that ensures a safe future for humanity," Whiteman said in a statement.