The two found plenty to disagree about, however. Pope's stressed the need to dramatically cut our carbon emissions pronto. "We should reduce CO2 emissions by two tons per day, or 80 percent, by 2050," he said, citing efficiency, compact communities, investment in public transit, and putting shipping on electrified rails as ways to achieve that goal.

"The places where we've extracted oil have suffered," he said. "We should accept the principle that toxic waste producers must take full responsibility for restoring those areas." He then issued a second challenge, suggesting that a global fund be established to clean up these communities, funded by 10 percent of oil company profits for the next ten years.

O'Reilly chose not to respond directly, instead emphasizing energy security and the fact that like the Sierra Club, Chevron cares deeply about the environment and energy efficiency. "What we disagree on is the extent to which renewable energy sources can replace fossil fuels, and how quickly that can happen. We must be realistic."

Asked how much he thought America's carbon emissions could be reduced by 2050, O'Reilly said 20 to 25 percent-although later in the debate he lowered that figure to 10 to 15 percent. "I think the American spirit is to do this much faster," countered Pope.

One of the evenings sharpest exchanges occurred after Pope said that the public and state governments were out ahead of the U.S. Congress in addressing climate change. "We need to acknowledge the warning we're getting from scientists, and the government has to enable energy companies to make this change," he asserted.

"Good luck getting government to move faster," O'Reilly said.

"It would help if you'd get out of the way," Pope replied.

As the evening progressed, both men emphasized and re-emphasized their main points, Pope stressing that energy efficiency can and must be brought about quickly, and O'Reilly countering that replacing conventional energy sources in a short period of time is unachievable. "We must be realistic in how quickly technology and economics will permit a transition away from fossil fuels," he said.

Asked why Chevron invests relatively little in renewable energy sources, O'Reilly pointed out that 2 percent of the company's budget goes to renewables, mostly geothermal, making it the biggest geothermal producer in the world.

"Why not wind energy?' asked Murray.

"We don't need to invest in wind energy,' O'Reilly replied. "We're in the fuels business, not the electricity business.

Asked what goals he had for Chevron by 2050, O'Reilly said, "We don't have a goal for anything by 2050 except to be a successful energy company. But we might be able to achieve a 10 to 15 percent CO2 reduction by 2050."

"For Chevron to be successful, it needs to change those numbers," Pope charged.

One of the evening's more amusing moments came when Murray read a question from the audience asking the two men's salaries.

"Around $200,000," Pope said.

"$14 million including bonuses," O'Reilly offered.

But in response to another audience question about how many lobbyists the two organizations deploy in Washington, Pope said the Sierra Club has 40 people in its D.C. office, "not all of whom are lobbyists." Chevron has about 20 lobbyists in the nation's capital.

As the debate drew to a close, one audience member shouted, "What about war? What about war for oil?" But Murray said that was a question for another time and place, and Pope and O'Reilly shook hands once again to sustained applause.

Check out the video of the conference:

Other cool stuff on Celsias:
Expanded Coalitions Support Climate Bill
Global Warming: Will Our Actions Stop A Grim Future?

Follow us on Twitter: Celsiastweets