Gore's comments came hours after the Nobel committee announced he would share the award with the U.N. Intergovernmental Panel on Climate Change for their work to raise awareness about global warming.

"This is a chance to elevate global consciousness about the challenges that we face now," Gore said, speaking to reporters in Palo Alto, California. "It truly is a planetary emergency, and we have to respond quickly."

The former vice president said he would donate his half of the $1.5 million prize to the Alliance for Climate Protection, an organization he founded to persuade people to reduce global warming by cutting pollution.

"That amount is very small compared to the enormous challenge that lies ahead," Gore said, including organizing a massive grass-roots movement and a mass advertising campaign focused on "trying to change the way people think."  Watch Gore describe what he calls a 'planetary emergency' »

Earlier Friday, a White House spokesman said President Bush was pleased that Gore, Bush's opponent in the 2000 presidential race, had won the award.

"Of course, he's happy for Vice President Gore, happy for the International Panel on Climate Change scientists, who also shared the Peace Prize," White House deputy press secretary Tony Fratto said. "Obviously it's an important recognition, and we're sure the vice president is thrilled."

Fratto said Bush would not be under any pressure to adopt mandatory caps on greenhouse gas emissions, a policy Gore has advocated.

Gore's ex-boss, former President Clinton, also said he's "thrilled by this well-deserved recognition," and credited Gore with "warning and educating us about the dangers of climate change for decades. He saw this coming before others in public life."

The Nobel committee's announcement cited Gore and the IPCC "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change."

The award ceremony will be held December 10 in Oslo, Norway.

In recent weeks, Gore has been the target of a campaign to persuade him to enter the 2008 presidential race.

 source involved in Gore's past political runs told CNN that he definitely has the ambition to use the peace prize as a springboard to run for president.

But he will not run, because he won't take on the political machine assembled by Sen. Hillary Clinton, said the source. If the senator from New York had faltered at all, Gore would take a serious look at entering the race, the source said. But Gore has calculated that Clinton is unstoppable, according to the source.

Gore repeatedly denied he has any plans to run again, but this week a group of grass-roots Democrats calling themselves "Draft Gore" took out a full-page ad in The New York Times in a bid to change his mind. Watch Gore discuss global warming and politics

"Your country needs you now, as do your party, and the planet you are fighting so hard to save," the group said in an open letter.

"America and the Earth need a hero right now, someone who will transcend politics as usual and bring real hope to our country and to the world."

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

"He is probably the single individual who has done most to create greater worldwide understanding of the measures that need to be adopted," said Ole Danbolt Mjos, chairman of the Nobel committee.

In making the announcement, Mjos said, "Through the scientific reports it has issued over the past two decades, the IPCC has created an ever-broader informed consensus about the connection between human activities and global warming.

"Thousands of scientists and officials from over 100 countries have collaborated to achieve greater certainty as to the scale of the warming."

Said Rajendra Pachauri, chairman of the U.N. panel: "This is an honor that goes to all the scientists and authors who have contributed to the work of the IPCC."

Renate Christ, secretary of the panel, called the award "the most significant recognition that the IPCC has received."

The Intergovernmental Panel on Climate Change was established in 1988 to study climate change information. The group doesn't do independent research but instead reviews scientific literature from around the world.

The U.N.-sanctioned group was formed by the World Meteorological Organization and U.N. Environment Program.

U.N. Secretary-General Ban Ki-moon said he was "delighted" with the news that Gore and the IPCC will share in prize.

The Nobel caps a series of prestigious awards associated with Gore, including two Oscars this year for the 2006 documentary film, "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 giving viewers the opportunity to create and influence its programming.

Previous American recipients of the peace prize include former Presidents Carter in 2002, Wilson in 1919 and Theodore Roosevelt in 1906.

In 1973, Secretary of State Henry Kissinger shared the award with North Vietnam's Le Duc Tho. The Rev. Martin Luther King Jr. received the honor in 1964

Gore was vice president for eight years before winning the 2000 Democratic presidential nomination and running against Bush.

But he failed in his White House bid -- despite winning the popular vote -- when the U.S. Supreme Court rejected his challenge over voting results in Florida, securing an Electoral College majority for Bush