More than 3,000 delegates representing 183 countries are attending a U.N. climate change conference in Bonn, Germany.
Christiana Figueres, executive secretary of the U.N. Framework Convention on Climate Change, said it was time to put words into action regarding climate change and a green energy future.
"The clean and renewable energy revolution has already begun," she said in a statement. "The challenge is to complete it in time."
World leaders at last year's climate conference in Cancun, Mexico, agreed to measures meant to limit the rate at which global temperatures increase.
"Now, more than ever, it is critical that all efforts are mobilized toward living up to this commitment," she said.
The International Energy Agency last week said global carbon emissions were moving closer to levels that shouldn't be reached for another 10 years if climate change is to be kept in check.