Former US Secretary of State John Kerry on Friday slammed US President Donald Trump's decision to pull out of the landmark Paris Climate Change Agreement.

Calling Trump's withdrawal from the Paris deal the "single greatest act of irresponsibility of any President of the United States at any time", he said, "Trump has pulled out of the Paris agreement, the American people have not." He was addressing the two-day closing plenary of the Global Climate Action Summit (GCAS) in this California city. It was co-chaired by California Governor Edmund G. Brown and UN Secretary-General's Special Envoy for Climate Action Michael R. Bloomberg.