U.N. Secretary General Ban Ki-moon said on Sunday he was hopeful that a goal of limiting global temperature rises to a maximum 2 degrees Celsius could be achieved, but urged governments to take practical action before it was too late.
"We have to ask the leaders to commit to bold ambitious targets and we will ask them to accelerate their actions on the ground," Ban told a two-day conference on climate change in the United Arab Emirates capital Abu Dhabi.
Ban said both meetings would be "solution shops" for an urgent problem.
Many developing nations want a one-day summit in New York on September 23 to be the deadline for rich countries to outline planned cuts in greenhouse gases beyond 2020, seen as a key step towards securing a global climate deal in 2015.
Governments have promised to limit temperature rises to a maximum 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial times to avert ever more heatwaves, floods, droughts and rising sea levels that the U.N.'s Intergovernmental Panel on Climate Change (IPCC) says are linked to man-made warming.
An IPCC report issued in April and endorsed by governments said such levels were still attainable but that policies currently in place put the world on target for a temperature rise of up to 4.8 C (8.6 F) by 2100.
Temperatures have already risen by about 0.8 C (1.4F) since the Industrial Revolution of the 18th and 19th centuries.
The report is the main scientific guide for nations working on a U.N. deal to be agreed in late 2015 to rein in greenhouse gas emissions that have hit repeated highs this century.
Ban said he would discuss the issue with Chinese leaders on a planned trip this month. Rapid industrial growth in China and other big developing countries has been blamed for increasing greenhouse gas emissions.
"We expect that China will do more and other BRIC (Brazil, Russia, India and China) countries will do more," Ban said without elaborating what measures he expected them to take.