Obama understands the global-warming threat, but failed to act decisively to change U.S. climate and energy policies -- instead knuckling under to well-financed oil-industry attacks and denial-and-delay ploys from congressional Republicans, the Democrat who won the 2007 Nobel Peace Prize for climate advocacy wrote in Rolling Stone magazine.
"After successfully passing his green stimulus package, he did nothing to defend it when Congress decimated its funding," Gore wrote. "After the House passed cap and trade, he did little to make passage in the Senate a priority."
Obama's greatest power, like that of any president, is the power to persuade, Gore said, citing the late political scientist Richard Neustadt.
Yet Obama has "never presented to the American people the magnitude of the climate crisis," Gore said. "He has simply not made the case for action."
Nor has Obama "defended the science against the ongoing, withering and dishonest attacks," Gore said.
Obama has had some success linking environmental security, economic security and national security, and more recently pushing to end oil and gas subsidies, Gore said.
"But in spite of these and other achievements, President Obama has thus far failed to use the bully pulpit to make the case for bold action on climate change," he wrote.
The White House defended Obama's record, saying Obama made clear "since Day 1" that climate change "poses a threat domestically and globally."
The United States, under Obama, has taken "the most aggressive steps in our country's history to tackle this challenge," including spending billions on clean-energy technology, imposing strict auto and truck emissions standards and taking the lead in international climate-change talks, spokesman Clark Stevens told The New York Times.
Gore also attacked unnamed GOP White House hopefuls "who have felt it necessary to abandon their previous support for action on the climate crisis; at least one has been apologizing profusely to the deniers and begging for their forgiveness."
In addition, Gore attacked the news media for putting out "claptrap on climate" rather than reporting climate change is real and is most likely caused by human activities.
A 2009 State of the World Forum, unrelated to Gore, cited scientific evidence indicating global temperatures would rise more than 7 degrees Fahrenheit by 2050 without radically accelerated plans to reverse global warming.
Among the many predicted catastrophic consequences was a massive migration of "millions, if not billions, of people into what are now Canada, Scandinavia and Russia," forum President Jim Garrison told United Press International at the time.
"Just imagine the political, military, cultural and humanitarian implications of this," said Garrison, who founded the forum with former Soviet President and Nobel Peace laureate Mikhail Gorbachev in 1995.
The forum called for "a new form of moral leadership that transcends the narrow self-interests that have so badly damaged our economies and prevented serious efforts to mitigate the escalating effects of climate change," Garrison told UPI then.