Dubai, UAE - The UN's COP28 climate summit opened with the launch of a "loss and damage" fund, which drew praise and hundreds of millions of dollars, but also warnings that much more is needed to help vulnerable nations.

"We have delivered history today," the UAE's COP28 president Sultan Al Jaber told delegates who stood and applauded after the decision's adoption in Dubai.

The announcement was followed immediately by financial pledges totaling $513 million – to which the US, by far the biggest polluter in history, only contributed $17.5.

After years of dragging their feet on the issue, wealthy nations backed the fund in a landmark agreement at the COP27 summit in Sharm el-Sheikh, Egypt, last year.

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Its launch on the first day of COP28 follows fraught negotiations on the mechanics of the fund, which will be housed at the World Bank on an interim basis.

"This sends a positive signal of momentum to the world," Jaber said.

He said it was "the first time a decision has been adopted on day one of any COP and the speed in which we have done so is also unique, phenomenal and historic."

"This is evidence that we can deliver. COP28 can and will deliver," he added.

But the money pledged so far fall well short of the $100 billion that developing nations – which have historically been least responsible for greenhouse gas emissions – have said are needed to cover losses from natural disasters.

"The progress we've made in establishing a loss and damage fund is hugely significant for climate justice, but an empty fund can't help our people," said Madeleine Diouf Sarr, chair of the Group of the 46 Least Developed Countries.

The Alliance of Small Island States, among the most impacted by rising seas and other effects of climate change, said "the work is far from over."

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"We cannot rest until this fund is adequately financed and starts to actually alleviate the burden of vulnerable communities," it said.

"Success starts when the international community can properly support the victims of this climate crisis, with efficient, direct access to the finance they urgently need," the group added.

Rachel Cleetus, policy director of the climate and energy program at the Union of Concerned Scientists, said the financial commitments should be "in the billions, not millions."

"Millions would be an insult given what's happening already around the world," Cleetus told reporters.

"We want to hear the starting point is a conversation about billions and then a plan to scale it up by 2030 so that it meets the needs that are clearly rising," she said.