The UN's COP28 climate conference formally launched on Thursday a "loss and damage" fund long sought by vulnerable nations devastated by natural disasters linked to global warming.

"We have delivered history today," the UAE's COP28 president Sultan Al Jaber told delegates, adding that his country was committing $100 million to the fund.

Germany also pledged $100 million.

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 last year.

Its launch on the first day of COP28 in Dubai 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 and to our work," Jaber said.

Jaber 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.