U.N. Secretary-General Ban Ki-moon urged world leaders on Thursday to make "bold pledges" for cuts in greenhouse gases by next September to guide a deal to fight climate change but acknowledged that many nations would be late.
Ban also told Reuters that rich nations' promises at U.N. climate talks in Warsaw for new funds to help the poor tackle more heatwaves, floods and rising sea levels caused by global warming were "insufficient".
Ban will host a one-day summit in New York on Sept. 23, 2014. Many developing nations want it to be a deadline for rich countries to outline planned cuts in greenhouse gases beyond 2020 as a key step towards a global climate deal in 2015.
Speaking on the sidelines of Nov. 11-22 U.N. climate talks in the Polish capital, Ban said he hoped world leaders would "announce bold actions, and bold commitments" at the summit.
But the United States has said it will unveil its plans for cuts in emissions beyond 2020 in early 2015. The European Union aims to announce its plans before the summit, giving time for a review by other nations.
"I met the U.S. delegations and I heard their positions," Ban said. "I understand that many countries still may not be ready, for their political or economic considerations."
"We may not need to wait until everybody declares their positions. So whoever can do, they should do by September next year," he said.
He also said it was "unusual" that Poland's Marcin Korolec, the president of the Warsaw talks, had lost his job as environment minister in a cabinet reshuffle on Wednesday.
"It was quite unexpected and unusual that the president of a (U.N. meeting) who was environment minister was relieved of this job," he said. Ban said Polish Prime Minister Donald Tusk had assured him Korolec would retain authority as president of the U.N. talks.
Some delegates saw the timing of the reshuffle as a sign that coal-dependent Poland, often reluctant to go along with European Union plans for tougher cuts in emissions, had little interest in the U.N. talks.
"I was told by my staff that it seems to be the first case" of a president of a U.N. meeting being demoted, Ban said.
In September, a U.N. panel of climate scientists raised the probability that global warming since 1950 is mainly manmade to at least 95 percent, from 90 percent in a former assessment in 2007 and 66 percent in 2001.
It said "sustained and substantial" cuts in greenhouse gases are needed to achieve a U.N. goal of limiting warming to less than 2 degrees Celsius (3.6 Fahrenheit) above pre-industrial times - widely seen as a threshold for dangerous change.
Developed nations agreed in 2009 to raise climate aid for developing nations to $100 billion a year from 2020 from an annual $10 billion for 2010-12. Hit by an economic slowdown, the rich are focused more on their economies than the climate and have not outlined plans for raising aid from 2013 to 2019.
"I am encouraged that pledges are now coming but I would urge member states, particularly donor countries, (to) be coming out more generously," he said. "It's not sufficient."
Many developing nations also want a new U.N. mechanism to help compensate for loss and damage from creeping effects of climate change, such as rising sea levels, desertification and ocean acidification.
Ban noted that many developing nations said $100 billion would be insufficient to cover such a new mechanism even though rich nations are reluctant.