BEVERLY HILLS, California: US President-elect Barack Obama on Tuesday vowed he would "engage vigorously" in global climate change talks and that denial was no longer an acceptable response to global warming.

Obama said in a surprise video message to an international conference on climate change hosted by five US state governors that he would show new leadership on the issue as soon as he takes office in January.

The President-elect also addressed his message directly to delegates at United Nations climate change talks in Poland next month.

"While I won't be president at the time of your meeting and while the United States has only one president at a time, I've asked members of Congress who are attending the conference as observers to report back to me on what they learn there," Obama said.

"And once I take office, you can be sure that the United States will once again engage vigorously in these negotiations, and help lead the world toward a new era of global cooperation on climate change.

"Now is the time to confront this challenge once and for all. Delay is no longer an option. Denial is no longer an acceptable response. The stakes are too high. The consequences, too serious."

Obama's comments came at the start of a two-day conference hosted by California Governor Arnold Schwarzenegger to discuss and develop strategies aimed at combating climate change.

Republican Schwarzenegger, who has repeatedly clashed with the outgoing administration of President George W. Bush over climate change issues, welcomed Obama's remarks.

"I'm very, very happy," he told delegates. "It's very important for our country, because we have been the biggest polluter in the world, it's time to work together with other countries to fight global warming."

Schwarzenegger was among five US governors hosting the event, which also features some 800 officials from Australia, Brazil, Canada, China, the European Union, India, Indonesia, Mexico, New Zealand, Poland, Spain, United Kingdom.

Schwarzenegger has vowed to make the environment a key issue of his second term in California and signed a historic bill in 2006 that saw California become the first in the nation to impose limits on global warming gases.

Under the plan, California will aim to slash the state's carbon dioxide emissions by 25 percent by the year 2020, a figure that Schwarzenegger has said is equivalent to removing 6.5 million vehicles from the road. - AFP/de