Chile's President Sebastian Pinera announces that he is calling off the Asia-Pacific Economic Cooperation Economic Forum, APEC, and Climate Change COP25 Conference, at La Moneda presidential palace in Santiago, Chile, Wednesday, Oct. 30, 2019. Pinera said that the ongoing protests have led him to call off the two major international summits that his country had been scheduled to host. (Ramon Monroy/ATON via AP)

WASHINGTON (AP) — Chile's abrupt decision Wednesday to withdraw as host of the United Nations' top climate conference leaves organizers scrambling for a second time to find a venue for the leading strategy sessions on global warming.

The annual U.N. conference has become the go-to place for diplomats and scientists from around the world to discuss how to tackle climate change, from setting rules on greenhouse gas reduction to helping poor countries cope with the effects of extreme weather and sea-level rise.

Chilean President Sebastian Pinera expressed "great pain" when he went on television to announce that 13 days of sometimes-deadly street protests and clashes forced the country to call off two major international summits, including the climate meeting scheduled for Dec. 2 to Dec. 13 that was to be a follow-up to the pivotal Paris climate accord in 2016.

Chile's reluctant cancellation comes after Brazil backed out of hosting the climate summit, after right-wing President Jair Bolsonaro won election last year. Some scientists were troubled by the news.

"Oh, dear," said Henry Jacoby, a climate expert at the Massachussetts Institute of Technology. "That's a shock to the system."

U.N. Climate Change Executive Secretary Patricia Espinosa issued a statement saying that "alternative hosting options" were being explored. And a U.N. official, speaking on condition of anonymity for lack of authorization to comment publicly, said all U.N. venues were being considered. Those would include New York, Geneva, Vienna and Bonn, Germany, and Nairobi, Kenya.

The Santiago conference was meant to work out some of the remaining unresolved climate rules, smoothing the way for a bigger effort in the 2020 summit: encouraging countries to increase their commitments to cutting emissions.

Skipping this year's conference entirely and leaving all the work for next year's summit could risk the success of that push for lower emissions, Jacoby said.

"To load everything into one" conference — "I think they'll work pretty hard not to do that," he said.

Rachel Cleetus, policy director at the Union of Concerned Scientists think tank and science advocacy group, said Chile's decision was understandable.

"It's a tough decision but the right one for Chile at the moment," she told The Associated Press.

As for whether the summit could be moved or postponed, Cleetus said "every effort" would be made to hold some type of meeting. She rejected the suggestion that the summits were a "talk fest" and skipping one would not make much of a difference.

Such conferences "are the venue where the global community comes together to decide how to tackle this problem together," she said. "The climate challenge requires every country to act, but it requires us to act collectively."

President Donald Trump committed to pulling out of the Paris accord as one of the first acts of his presidency. The United States still sends a team to the summit, however. A State Department spokesman did not immediately return a request for comment for any planning following Chile's withdrawal.

In this photo released by Chile’s presidential office, President Sebastian Pinera, center, accompanied by Chile's Foreign Minister Teodoro Ribera, left, and Environment Minister Carolina Schmidt, announces that he is calling off the Asia-Pacific Economic Cooperation Economic Forum, APEC, and Climate Change COP25 Conference, at La Moneda presidential palace in Santiago, Chile, Wednesday, Oct. 30, 2019. Pinera said that the ongoing protests have led him to call off the two major international summits that his country had been scheduled to host. (Marcelo Segura/Chile's Presidential Office via AP)
Anti-government demonstrators march past La Moneda presidential palace in Santiago, Chile, Wednesday, Oct. 30, 2019. President Sebastian Pinera cancelled two major international summits after nearly two weeks of nationwide protests over economic inequality that have left at least 20 dead and damaged businesses and infrastructure around the country. (AP Photo/Rodrigo Abd)
Anti-government demonstrators gather outside La Moneda presidential palace in Santiago, Chile, Wednesday, Oct. 30, 2019. Chilean President Sebastián Pinera cancelled two major international summits after nearly two weeks of nationwide protests over economic inequality that have left at least 20 dead and damaged businesses and infrastructure around the country.(AP Photo/Rodrigo Abd)