Armed with diagrams and charts that would make Al Gore proud, scientists and Bush administration officials came to Capitol Hill to brief Congress on global warming.
Also today, one senator announced legislation to reduce greenhouse gas emissions 80 percent by 2050.
Some say the renewed focus in Washington is a sign that lawmakers are paying closer attention to an issue they may have to deal with sooner rather than later. But the day was not without controversy.
All of the witnesses testifying today in front of the House Committee on Government Reform agreed on several basic points: global warming is real, humans are causing it and Congress should act to address it. But there were disagreements over exactly what should be done and how fast.
Jim Connaughton, the president's policy advisor on global warming, said that President Bush thinks the issue is serious and that "humans are a big part of the problem." He said the next step is to find "sensible" ways to deal with it.
Connaughton touted the administration's list of more than 60 federal programs to address greenhouse gas emissions.
"By the end of the year, the administration will have devoted over $29 billion in taxpayer resources -- more than any other nation -- to climate science technology," Connaughton said.
"These and many other efforts are working," he said. "We are on track to meeting the president's goal."
His remarks drew immediate criticism from Rep. Henry Waxman, D-Calif., the ranking member on the committee.
"All the things you enthusiastically reported to us aim to get you to the president's global warming goal," Waxman said. "But that goal actually allows U.S. emissions of global warming pollution to rise 14 percent by 2012. Your plan is to let emissions to go up a lot. Are you trying to tell us that allowing emissions to rise is prompt action?"
Connaughton responded: "It's significantly better than the alternative path we are on."
But Waxman continued to downplay the administration's plan.
"Your goal barely even slows the growth of emissions," he said. "These types of shell games just reinforce the point that the Bush administration has very little credibility on this issue."
The Intergovernmental Panel on Climate Change, an international group of peer-reviewed scientists, predicts that global temperatures may rise anywhere from about 3 to 9 degrees Fahrenheit over the next century. The earth is already seeing the effects of a one-degree average temperature rise in only a century, primarily due to the burning of fossil fuels that release heat-trapping gases like carbon dioxide.
That one degree has already had effects, such as accelerated melting of glaciers and polar ice caps along with increased sea level rise, according to Jay Gulledge, a senior Research Fellow at the Pew Center on Global Climate Change.
"The observed changes in the climate tell us that in fact the climate system globally is quite sensitive to these levels of changes," Gulledge testified as he showed off various charts and graphs. "The changes have been faster than expected, which tells us we've probably underestimated the sensitivity of the climate system in the past."
Jeffords Calls for Reduced Emissions
Elsewhere on Capitol Hill today, Sen. Jim Jeffords, I-Vt., announced legislation that calls for mandatory incremental greenhouse gas emissions cuts: 2 percent each year from 2010 to 2020, and eventually rising to 80 percent by 2050.
Jeffords' "Global Warming Pollution Reduction Act" is similar to one Rep. Waxman introduced earlier this spring.
Several policy watchers said the recent activity in Congress is a sign that lawmakers are beginning to take global warming more seriously.
"There's definitely an upswing in the tempo," says Alden Meyer, director of strategy and policy at the Union of Concerned Scientists. "You're seeing more and more awareness on Capitol Hill that the problem is real and it's already having impacts. It's getting harder and harder to disagree about it."
But efforts to pass mandatory caps on greenhouse gas emissions have failed before, including 2005 legislation sponsored by Sen. John McCain, R-Ariz., and Sen. Joe Lieberman, D-Conn. After that defeat, New Mexico senators Jeff Bingaman (D) and Pete Domenici (R) successfully passed a resolution that called for mandatory steps to reduce greenhouse gas emissions, but it was non-binding.
Will things be different this year?
"We don't necessarily expect climate change legislation to be voted on this year," says Antonia Herzog with the National Resources Defense Council. "But I would call it the year of ideas."