Former Secretary of State John Kerry returned to the public spotlight Monday suggesting that the threat of climate change outweighs a nuclear attack from North Korea.

“A nuclear weapon overtly brandished in the hands of the wrong person, in the wrong country, receives significant focus and crisis management, and rightly so,” Kerry said. “But a silent killer that compounds its destructive power daily and threatens the lives of literally billions of people with increasing destructive force is ignored and even mocked.”