He accused skeptics of using shoddy science and scientists.
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U.S. Secretary of State John Kerry on Sunday called climate change perhaps the world’s “most fearsome” destructive weapon and mocked those who deny its existence or question its causes, comparing them to people who insist the Earth is flat.

In a speech to Indonesian students, civic leaders and government officials, Kerry tore into climate change skeptics. He accused them of using shoddy science and scientists to delay steps needed to reduce emissions of greenhouse gases at the risk of imperiling the planet.

A day earlier, the U.S. and China announced an agreement to cooperate more closely on combating climate change. American officials hope that will help encourage others, including developing countries like Indonesia and India, to follow suit.