Leaders from the world's emerging economies and G8 countries have agreed to limit global warming to within 2 degrees Celsius above pre-industrial levels. But they failed to hammer out more substantial targets of cutting greenhouse gas emissions.

Italian Prime Minister Silvio Berlusconi (R) speaks alongside US President Barack Obama during a press conference at the Group of Eight (G8) summit in L'Aquila, central Italy. [Saul Loeb/CCTV/AFP]

Leaders from a 17-nation group called the Major Economies Forum struck a deal to limit global warming at a summit in L'Aquila, Italy on Thursday. The group includes the G-8 countries namely Canada, Britain, France, Germany, Italy, Russia, Japan and the United States. And it also includes China, India, Mexico, Brazil, South Africa, Indonesia, Australia, South Korea and the EU.

This is the first time that the rich and emerging nations together declared that average global temperatures should not rise higher than two degrees Celsius above those of pre-industrial times.

But, they made no commitments to do anything in the near term, for example by 2020, to reach that goal.

UN Secretary-General, Ban Ki-Moon, was sharply critical of the leaders for failing to make more commitments to reducing climate change in the near future.

Ban Ki-Moon, UN Secretary-General, said, "The policies that they have stated so far is not enough, is not sufficient enough, to meet the targets that the scientists of the Intergovernmental Panel on Climate Change have suggested. This is the science. We must work according to the science. This is politically and morally imperative and a historic responsibility for the leaders for the future of humanity."