In an open letter to the president of the COP 25 talks, Chile's environment minister Carolina Schmidt, the organisations urged agreement on "the creation of a comprehensive financing facility, including debt relief, for developing countries experiencing such disasters."

They said money should come from wealthy nations -- historically most responsible for planet-warming carbon emissions -- in the form of tax on financial transactions, international air travel and fossil fuels.

The Madrid conference is set to be dominated by discussions on so-called "loss and damage" funding, with a sharp divide between developing nations and richer polluters over how finance should be structured.

Green groups this week said the increased pace and intensity of climate disasters, such as the twin cyclones that devastated parts of Mozambique this year, means that funding needs boosting to keep track.

They said the amount needed for loss and damage would top $300 billion annually by 2030.

"Without finance to help countries cope with climate-induced loss and damage, the most vulnerable parts of the world will sink deeper into debt and poverty every time they are hit by climate disasters they did not cause," the letter said.

Storms in Mozambique this year displaced millions, destroyed homes and crops, inflicting an estimated $3 billion in damages -- roughly 20 percent of the country's GDP.

But without a global, unified process for climate damage funding, countries are not yet obliged to get their chequebooks out.

After Cyclone Idai, the International Monetary Fund provided Mozambique with an emergency load of $118 million -- woefully short of what was needed.

"Wealthy countries have been ignoring developing nations' demands for financial support to repair the loss and damage caused by climate disasters," said Harjeet Singh, global climate change lead at ActionAid.

"Meanwhile, the climate crisis has been causing death, despair and displacement in the Global South."