( BBC ) - Al Gore says his Nobel Peace Prize is an "honour" and a chance to "elevate global consciousness" about the threat posed by climate change.
The former US vice-president was awarded the prestigious prize jointly with the UN's Intergovernmental Panel on Climate Change (IPCC).
The committee cited "their efforts to build up and disseminate knowledge about man-made climate change".
Mr Gore won an Oscar for his climate change film An Inconvenient Truth.
He said he accepted the award on behalf of scientists - like those in the IPCC - who had worked tirelessly for years to get the message about global warming out.
"This is the most dangerous challenge we've ever faced," he said, speaking in Palo Alto, California, some hours after the award was announced.
"I will be doing everything I can to try to understand how to best use the honour and recognition of this award as a way of speeding up the change in awareness, and the change in urgency.
"I'm going back to work right now. This is just the beginning," he said, walking out of the room after less than five minutes, and without taking questions.
The Norwegian Nobel Committee said it wanted to bring into sharper focus the "increased danger of violent conflicts and wars, within and between states" posed by climate change.
Mr Gore, 59, was praised as "probably the single individual who has done most to create greater worldwide understanding of the measures that need to be adopted", through his lectures, films and books.
He said he would donate his half of the $1.5m prize money to the Alliance for Climate Protection.
Mr Gore's selection has prompted supporters to renew calls for him to stand in next year's US presidential race. Until now, Mr Gore has said he will not run.
President George W Bush, who defeated Mr Gore in a bitter fight for the presidency in 2000, was "happy" at the "important recognition" for his rival and the IPCC, a White House spokesman said.
However, the president was not about to change his more sceptical stance on global warming to a more "Gore-style" approach, the spokesman said.
The former vice-president has emerged as a leading climate campaigner. His 2006 documentary film, An Inconvenient Truth, was an unlikely box-office hit and won two Oscars - though it was also criticised by a British judge this week for containing nine errors, and for being alarmist.
The IPCC, established in 1988, is tasked with providing policymakers with neutral summaries of the latest expertise on climate change.
The organisation involves hundreds of scientists working to collate and evaluate the work of thousands more.