Gore, a vice president to Bill Clinton and failed candidate for the White House in 2000, has reinvented himself as a champion of climate change with his 2006 Oscar-winning documentary "An Inconvenient Truth". The IPCC, a UN body comprised of about 3,000 atmospheric scientists, oceanographers, ice specialists, economists and other experts, is the world's top scientific authority on global warming and its impact. Gore, who won an Academy Award earlier this year, had been widely tipped to win the prize.

''His strong commitment, reflected in political activity, lectures, films and books, has strengthened the struggle against climate change,'' the citation said. ''He is probably the single individual who has done most to create greater worldwide understanding of the measures that need to be adopted.''

The Nobel committee praised Gore as being "one of the world's leading environmentalist politicians."

Gore collected two Oscars earlier this year for his documentary, An Inconvenient Truth, which followed him on a worldwide tour publicizing the dangers of climate change.

Last month he also picked up an Emmy -- the highest award in U.S. television -- for "Current TV." The show, which Gore co-created, describes itself as a global television network that gives its viewers the opportunity to create and influence its programming.

This year, climate change has been at the top of the world agenda. The UN climate panel has been releasing its reports; talks on a replacement for the 1997 Kyoto Protocol on climate are set to resume; and on Europe's northern fringe, where the awards committee works, concern about the melting Arctic has been underscored by this being International Polar Year.

In recent years, the Norwegian committee has broadened its interpretation of peacemaking and disarmament efforts outlined by Swedish industrialist Alfred Nobel in creating the prize with his 1895 will. The prize now often also recognizes human rights, democracy, elimination of poverty, sharing resources and the environment.

Two of the past three prizes have been untraditional, with the 2004 award to Kenya environmentalist Wangari Maathai and last year's award to Bangladeshi economist Muhammad Yunus and his Grameen Bank.

The UN body that won the Nobel Peace Prize was surprised that it was chosen to share the honor with Al Gore for their work on climate change, the spokeswoman said.

''It was a surprise,'' said Carola Traverso Saibante of the Intergovernmental Panel on Climate Change, a UN network of 2,000 scientists. ''We would have been happy even if he had received it alone because it is a recognition of the importance of this issue.''

Gore served as vice president for eight years under President Bill Clinton. In 2000, he garnered the Democratic presidential nomination and faced off against Texas Gov George W Bush.

Gore won the popular vote but lost the election vote after the US Supreme Court denied his challenge of voting results in the key state of Florida.