Poor countries must find $4tn by 2030 to avert catastrophe, says climate study

As Paris climate change agreement is signed in New York, developing country negotiators highlight gulf between ambition and funding

Developing countries must raise more than $4tn (2,456bn), or roughly the entire annual budget of the US, to implement their climate change pledges by 2030, according to new research.

But much more money will have to be be found by the world's poorest countries to hold global temperatures enough to avoid catastrophic climate change, say British and Australian researchers who have analysed the financial implications of the pledges made to the UN last December and the money so far offered by rich countries.