Former US Vice President Al Gore and the United Nation's Intergovernmental Panel on Climate Change (IPCC) will share this year's Nobel Peace Prize.
The award is considered a significant boost to the anti-global warming campaign carried on assiduously by Gore and the UN panel.
The awarding committee cited "their efforts to build up and disseminate knowledge about man-made climate change."
Gore, 59, said he was "deeply honoured" while IPCC chairman Rajendra Pachauri, an Indian scientist, said he was "overwhelmed."
Gore was behind a blockbuster film on climate change, while the IPCC is the top authority on global warming.
Announcing the award, the Norwegian Nobel Committee praised the recipients' efforts to "lay the foundations for the measures that are needed to counteract [climate] change."
It said it wanted to bring the "increased danger of violent conflicts and wars, within and between states" posed by climate change into sharper focus.
The committee highlighted the series of scientific reports issued over the last two decades by the IPCC, which comprises more than 2,000 leading climate change scientists. The reports had "created an ever-broader informed consensus about the connection between human activities and global warming."
Gore 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.
Speaking in Washington, Gore said he was honoured.
"This award is even more meaningful because I have the honour of sharing it" with the IPCC, he said, "whose members have worked tirelessly and selflessly for many years."
He said he would donate his half of the $1.5m prize money to the Alliance for Climate Protection.
"I can't believe it, overwhelmed, stunned," IPCC chairman Rajendra Pachauri told reporters and co-workers after receiving the news on the phone at his office in Delhi.
He later told a cheering crowd of co-workers and journalists outside his office in New Delhi he hoped the award would bring a "greater awareness and a sense of urgency" to the fight against global warming.
A massive amount of work goes on behind the scenes at the IPCC, involving hundreds of scientists working to collate and evaluate the work of thousands more. In a sense, he says, this is an award for those usually unsung scientists too.
Gore made a failed bid for the US presidency in 2000, after serving as vice-president under Bill Clinton. Since then he has emerged as a leading climate campaigner - winning an Oscar for his 2006 film An Inconvenient Truth, an unlikely box-office hit.
The IPCC, established in 1988, is tasked with providing policymakers with neutral summaries of the latest expertise on climate change.