It remains technically possible to keep planetary warming to a tolerable level, the Intergovernmental Panel on Climate Change found, according to a report released here. But even in parts of the world such as Europe that have tried hardest, governments are still a long way from taking the steps that are sufficient to do the job, the experts found.

BERLIN — The countries of the world have dragged their feet so long on global warming that the situation is now critical, analysts appointed by the United Nations reported Sunday, and only an intensive worldwide push over the next 15 years can stave off potentially disastrous climatic changes later in the century.


“We cannot afford to lose another decade,” said Ottmar Edenhofer, a German economist and cochairman of the committee that wrote the report. “If we lose another decade, it becomes extremely costly to achieve climate stabilization.”

The report is likely to increase the pressure to secure an ambitious new global climate treaty that is supposed to be completed in late 2015 and take effect in 2020. But the divisions between wealthy countries and poorer countries that are making such a treaty difficult, and have long bedeviled international climate talks, were on display yet again in Berlin.

Some developing countries insisted on stripping charts from the report’s executive summary that could be read as requiring greater effort from them, while rich countries, including the United States, struck out language implying they needed to write big checks to the developing countries.

Both points survived in the full version of the report, but they were deleted from a synopsis meant to inform the world’s top political leaders.

The report did find some reasons for cautious optimism. The costs of such renewable energy as wind and solar power are now falling so fast that their deployment on a large scale is becoming practical, the report said. In fact, extensive use of renewable energy is already starting in countries such as Denmark and Germany, and to a lesser degree in some US states, including California, Iowa, and Texas.


Moreover, since the intergovernmental panel issued its last major report in 2007, many more countries, states, and cities have adopted ambitious climate plans, an indication that the political determination to tackle the problem is growing in many parts of the world.

They include China and the United States, which are both doing more domestically than they have been willing to commit themselves to in international treaty negotiations.

The Intergovernmental Panel on Climate Change is a UN body that includes hundreds of scientists, economists and other experts. The group periodically reviews the science and economics of climate change and issues major reports every five to six years.