(CNN) - Former vice president and environmental advocate Al Gore sharply criticized President Obama's "failed" approach to global warming Wednesday, forcing the White House to defend its record on climate change.
Gore was supportive of Obama's action in the first six months of his administration, but the former Democratic presidential nominee said the administration has not made the case for action among the American people.
"President Obama has thus far failed to use the bully pulpit to make the case for bold action on climate change," Gore wrote in a "Rolling Stone" article published online. "After successfully passing his green stimulus package, he did nothing to defend it when Congress decimated its funding."
"Without presidential leadership that focuses intensely on making the public aware of the reality we face, nothing will change," Gore added.
But in a written response to Gore’s essay Wednesday White House official Clark Stevens outlined a number of policies the administration implemented in the last two years, including investments in clean energy through the Recovery Act that set “aggressive new joint fuel economy and emissions standards for cars and trucks,” reducing greenhouse gas emissions by "960 metric tons."
“The President has been clear since day one that climate change poses a threat domestically and globally, and under his leadership we have taken the most aggressive steps in our country’s history to tackle this challenge,” Stevens said.
Since losing the 2000 presidential election, Gore has championed global warming and advocated for a transition to clean energy. He won the Nobel Prize for his environmental efforts in 2007.
Obama, he said, has not defended the science of global warming or provided a "presidential venue" to bring the data before the public.
Although he acknowledged the political difficulty in taking a stand on the issue, Gore said the president has facts to back up his opinions.
"Assuming that the Republicans come to their sense and avoid nominating a clown, his re-election is likely to involve a hard-fought battle with high stakes for the country," Gore wrote. "But in this case, the president has reality on his side."
Updated 4:44 p.m.