WASHINGTON (AP) — The United States will give $3 billion to a U.N.-established fund to help poorer vulnerable countries prepare for a changing climate and develop cleaner energy, President Barack Obama announced Saturday.

The United Nations is trying to raise at least $10 billion for its Green Climate Fund to help developing nations adjust to rising seas, warmer temperatures and more extreme weather. It also would help the nations come up with energy sources that limit or reduce heat-trapping carbon dioxide emissions from coal, oil and gas.

Obama said the money would help farmers plant more resilient crops, governments to cut carbon dioxide emissions and communities to develop better defenses against storm surges and other climate-related changes.

But Obama said combating climate change cannot be the work of government alone. “Citizens— especially young people like you — have to keep raising your voices, because you deserve to live your lives in a world that is cleaner and healthier,” he said while announcing the pledge during a speech at a university in Brisbane, Australia.

The American pledge would be the biggest to date and would double contributions to $6 billion, according to international environmental groups.

France has promised $1 billion, with Germany pledging nearly as much. Sweden, the Netherlands and Switzerland have all pledged at least $100 million, while Denmark, Norway, Mexico, Luxembourg, Czech Republic and Indonesia have pledged lesser amounts, according to officials at Oxfam America.

The South Korea-based fund, which also accepts money from private charities, was set up by the United Nations Framework Convention on Climate Change.

It wasn’t immediately clear where Obama planned to find the money. Sen. Timothy Wirth, vice chairman of the United Nations Foundation and a politician who has been on both House and Senate budget committees, said he doesn’t see how the Obama administration can get the money without approval from a Republican Congress, which he said is unlikely to happen.

But Wirth said that will work out because “almost all of this is going to be done by the private sector.” The idea is eventually to have about $100 billion flowing to the developing nations, he said.

In an effort to ensure other countries also chip in, the White House said its $3 billion pledge was contingent on the U.S. contribution not exceeding 30 percent of total confirmed pledges. The White House said it expected the U.S. share would decline over time as more countries join the effort.

“Symbolically, I think it shows bold action to keep advancing his climate agenda” despite a Republican Congress that may not even believe in global warming, said Paul Wapner, a professor of international relations and environmental politics at American University.

Chip Knappenberger of the conservative Cato Institute said his preference is for private money to go the fund. And if federal money goes to the fund it should be more to help the nations adapt to a changing climate rather than push greener energy sources, he said.

Along with several environmental activist groups, former Vice President Al Gore cheered the announcement as “strong leadership,” heading into intense climate negotiations for a new international treaty next year.

Sen. James Inhofe, R-Okla., who will likely be the new chairman of the Senate Environment and Public Works Committee, blasted the pledge in a statement, saying it’s part of more than $120 billion in spending on climate change since the president took office: “President Obama’s pledge to give unelected bureaucrats at the U.N. $3 billion for climate change initiatives is an unfortunate decision to not listen to voters in this most recent election cycle.”

In 2008, President George W. Bush pledged $2 billion to a similar fund. The Obama administration said it is building on that pledge.

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