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.

China and the United States are the biggest sources of emissions of carbon dioxide and other gases that cause the atmosphere to trap solar heat and alter the climate. Scientists say such changes are leading to drought, wildfires, rising sea levels, melting polar ice, plant and animal extinctions and other extreme conditions.

Also in the Jakarta speech, Kerry said everyone and every country must take responsibility for the problem and act immediately.

"We simply don't have time to let a few loud interest groups hijack the climate conversation," he said, referring to what he called "big companies" that "don't want to change and spend a lot of money" to act to reduce the risks.

Kerry later singled out major oil and coal concerns as the primary offenders.

"We should not allow a tiny minority of shoddy scientists and science and extreme ideologues to compete with scientific facts," Kerry told the audience at a U.S. Embassy-run American Center in a shopping mall.

"Nor should we allow any room for those who think that the costs associated with doing the right thing outweigh the benefits."

"The science is unequivocal, and those who refuse to believe it are simply burying their heads in the sand," Kerry said. "We don't have time for a meeting anywhere of the Flat Earth Society,"

Kerry said the cost of inaction will far outweigh the significant expense of reducing greenhouse gas emissions that trap solar heat in the atmosphere and contribute to the Earth's rising temperatures.

He outlined a litany of recent weather disasters, particularly flooding and typhoons in Asia, and their impact on commerce, agriculture, fishing and daily living conditions for billions of people.

"This city, this country, this region, is really on the front lines of climate change," Kerry said. "It's not an exaggeration to say that your entire way of life here is at risk."

He added: "In a sense, climate change can now be considered the world's largest weapon of mass destruction, perhaps even, the world's most fearsome weapon of mass destruction."

The solution, Kerry said, is a new global energy policy that shifts reliance from fossil fuels to cleaner technologies. He noted the President Barack Obama is championing such a shift and encouraged others to appeal to their leaders to join.

The U.S.-China statement issued just after Kerry left Beijing on Saturday said the two countries agreed on steps to carry out commitments to curb greenhouse gases, including reducing vehicle emissions, improving energy efficiency of buildings and other measures.

Beijing and Washington launched a climate change discussion last year, promising progress in five areas: reducing vehicle emissions; advanced electric power grids; capturing and storing carbon emissions; gathering greenhouse gas data; and building efficiency.

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Kerry was in Indonesia on the last leg of a three-nation tour of Asia that started in South Korea. After leaving Indonesia on Monday, he planned to visit Abu Dhabi in the United Arab Emirates.

Before the climate change speech, Kerry toured Jakarta's Istiqlal Mosque, one of the largest in the world, to pay his respects to Indonesia's Muslim majority population.