Ban Ki-moon: "The policies stated so far are not enough"
UN Secretary General Ban Ki-moon has criticised leaders of the G8 industrial nations for failing to make deeper commitments to combat climate change.
On Wednesday, the leaders, meeting in Italy, agreed to cut emissions by 80% by 2050, but Mr Ban said big cuts were needed sooner rather than later.
The leaders are set to meet their counterparts from emerging economies to discuss a new deal on global warming.
US President Barack Obama will chair the session, in the city of L'Aquila.
Richard Black, BBC News
Now G8 leaders will try to persuade some major developing countries to halve global emissions by 2050. Governments such as China's, that are concerned about climate impacts, may find the figure desirable. But they are unlikely to be impressed with what they see as fine words from the West unmatched by real short-term commitments.
Unmatched, too, by money. Of the major developing nations, India especially has long argued that it will not compromise its economic growth by agreeing to climate curbs.
So if the West wants the developing world to go through its own energy revolution, it is going to have to fund a lot of it.
Our correspondent adds that India is already complaining that the G8's long-term targets for 2050 are too long-term and that G8 countries are ducking interim targets for 2020 which would make their 40-year ambitions more credible.
But in a meeting with Brazilian President Luis Inacio Lula da Silva, Mr Obama said there was still time to close the gap between developed and developing nations before UN talks on a new climate change treaty in Copenhagen in December.
The summit host, Italian Prime Minister Silvio Berlusconi, has said a deal should be all-inclusive.
"It would not be productive if European countries, Japan, the United States and Canada accepted cuts that are economically damaging while more than five billion people in other countries carried on as before," he said.
The G8 summit began in L'Aquila on Wednesday, with the first day largely taken up with discussion of the fragile state of the global economy.
The leaders also issued a statement reaffirming that they were "deeply concerned" by Iran's nuclear programme and condemning North Korea's recent nuclear test and missile launches.
African leaders will join the summit on Friday to push for a new initiative to fund farming in the developing world and tackle global hunger.
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