Elon Musk has made good with his promise to leave President’s Trump’s advisory councils following the U.S.’s withdrawal from the Paris Agreement.

Taking to Twitter, Musk said “Am departing president councils. Climate change is real. Leaving Paris is not good for America or the world.” Musk had been a member of Trump’s infrastructure council, his manufacturing jobs council and the President’s strategic and policy forum.

The Paris Agreement, agreed to in December 2015, saw 195 countries provide commitments to combat climate change. By withdrawing, the United States becomes just the third country on earth not to have signed the agreement, joining Syria and Nicaragua, the latter of which didn’t sign because it thought the agreement wasn’t tough enough.

On the back of Trump’s decision, the governors of California, Washington and New York have all agreed to form an alliance to achieve climate goals.

In a statement, Governor Jerry Brown said “If the President is going to be AWOL in this profoundly important human endeavor, then California and other states will step up.”

President Trump has claimed that the Paris Agreement would punish it and stymie economic growth, hurting local workers.