U.S. special envoy for climate John Kerry speaks during a roundtable meeting with reporters in Seoul on Sunday. The United States and China have agreed to cooperate with other countries to curb climate change, just days before a virtual summit of world leaders to discuss the issue.

In this photo provided by U.S. Embassy Seoul, U.S. special envoy for climate John Kerry gestures while speaking during a round table meeting with the media in Seoul, South Korea, Sunday, April 18, 2021. The United States and China, the world’s two biggest carbon polluters, have agreed to cooperate with other countries to curb climate change, just days before U.S. President Joe Biden hosts a virtual summit of world leaders to discuss the issue. (U.S. Embassy Seoul via AP)