RENEWED PLEDGE: TO Clean Energy sources, Obama

President Obama joined other world leaders Tuesday in calling for immediate and substantive steps to combat climate change, saying failure to act now would bring “irreversible catastrophe.”

Speaking to a special summit on climate change at the United Nations, Obama pledged the full commitment of the United States to a global response after what he called years of responding too slowly to the magnitude of the challenge.

However, Obama’s speech lacked specific details on cutting greenhouse gas emissions that cause climate change. He also warned that the global economic recession could hinder the ability of countries to take necessary steps to combat climate change.

“We seek sweeping but necessary change in the midst of a global recession, where every nation’s most immediate priority is reviving their economy and putting their people back to work,” Obama said. “And so all of us will face doubts and difficulties in our own capitals as we try to reach a lasting solution to the climate challenge.”

Progress in the negotiations involving almost 200 countries has been slowed by disputes over the roles of industrialized powers and major greenhouse gas emitters such as the United States and emerging nations such as China that have become major emitters in their rush to economic development.

China will increase efforts to improve energy efficiency and curb the rise in CO2 emissions, President Hu Jintao has told a UN climate summit in New York. Mr Hu gave no details about the measures, which should mean emissions grow less quickly than the economy. The US, the world’s other major emitter, said China’s proposals were helpful but figures were needed.

About 100 leaders are attending the talks, ahead of the Copenhagen summit which is due to approve a new treaty. UN Secretary General Ban Ki-moon said failure to agree a treaty in December would be “morally inexcusable”.

Negotiators for the Copenhagen summit are trying to agree on a replacement for the Kyoto Protocol to limit carbon emissions.