U.S. Secretary of State John Kerry warned Indonesians on Sunday that man-made climate change could threaten their entire way of life, deriding those who doubted the existence of “perhaps the world’s most fearsome weapon of mass destruction”.

Kerry described those who do not accept that human activity causes global warming as “shoddy scientists” and “extreme ideologues”, and said big companies and special interests should not be allowed to “hijack” the climate debate.

Aides said Kerry had chosen Indonesia for the first of what is to be a series of speeches on the topic this year partly because, as an archipelago of more than 17,000 islands, it is particularly at risk from rising sea levels.

Kerry, who faces a politically tricky decision at home on whether to allow Canada’s TransCanada Corp to build the Keystone XL pipeline over the opposition of environmental groups, had little patience for such skeptics in his speech.