The United Nations' chief negotiator on climate change says wealthy nations will have to find at least $US10 billion to help developing countries deal with climate change.
Yvo de Boer says that commitment would be one measure of success for a climate change conference to be held in Copenhagen in December.
Mr de Boer says $US10 billion is just the bare minimum to help developing nations.
Two other critical issues have to be resolved at the conference, the BBC reports.
Richer nations have to adopt stringent targets to reduce their carbon output by 2020, while the larger developing nations such as China, India and Brazil have to come forward with plans to reduce their carbon footprints.
Mr de Boer says countries cannot continue with their business as usual approach.
Leading nations participating in the summit must, he says, sign an agreement to reduce greenhouse gas emissions.
A failure to provide clear answers on all three of these political issues would mean that the Copenhagen conference would have failed - and failure there, Mr de Boer says, will mean a lot of trouble for everyone.
