British citizens have voted to leave the European Union by 52–48 percent. Environmentalists and climate hawks are worried about what that might mean.

Many green leaders had called on voters to oppose a British exit from the EU — or Brexit — arguing that the EU has raised environmental standards in the U.K. and the rest of Europe. They noted that environmental problems are international in nature, so international cooperation is necessary to fight them effectively.

Outgoing United Nations climate head Christiana Figueres also warned against Brexit, saying earlier this week that the U.K. increased the ambition of European climate negotiators before and during the Paris climate talks last December.