DENVER -- Even as governments worldwide have largely failed to limit emissions of global warming gases, the decline of fossil fuel production may reduce those emissions significantly, experts said yesterday during a panel discussion at the Geological Society of America meeting.

Conventional production of oil has been on a plateau since 2005, said James Murray, a professor of oceanography at the University of Washington, who chaired the panel.

As production of conventional oil, which is far easier to get out of the ground, decreases, companies have turned to unconventional sources, such as those in deep water, tar sands or tight oil reserves, which have to be released by hydraulic fracturing.

But those techniques tend to lead to production peaks that tail off quickly, Murray said.

The panelists said these trends belie the high-end emission scenario from the Intergovernmental Panel on Climate Change (IPCC). That scenario, known as RCP 8.5, and often referred to as the "business as usual" scenario, has carbon dioxide emissions increasing through 2100.

"I just think it's going to be really hard to achieve some of these really high CO2 scenarios," Murray said.

David Rutledge, an engineering professor at the California Institute of Technology who studies world coal production, said the IPCC's "business as usual" scenario is unrealistic because it essentially assumes that growth of fossil fuels like coal will continue apace, which is unlikely.

Recovery estimates may be too high

In reality, governments tend to overestimate their coal reserves, and much of these reserves will never be accessed, Rutledge said.

"There is little relationship between the RCPs and the actual historical experience of oil, gas and coal production," Rutledge said.

Rutledge said of the four IPCC scenarios, he found the second RCP scenario, RCP 4.5, where carbon dioxide emissions flatten out around 2080, to be more plausible under a business-as-usual scenario for coal exploitation.

"4.5 would be the closest one if you look at the mining history," Rutledge said. "My own opinion is that no one should use RCP 8.5 for any purpose at all."

David Hughes, of Global Sustainability Research Inc., pointed out that production from tight oil fields like North Dakota's Bakken and Texas' Eagle Ford plays quickly reach what he called "middle age," when production begins to fall off.

He said it is likely that the Bakken Shale oil play will peak in 2015 or 2016 and that the Eagle Ford Shale play, another significant U.S. oil production area, will peak soon after.

"Long-term [production] sustainability is highly questionable, and environmental impacts are a major concern," Hughes said.

The United States should see the temporary bounty of oil from these sources as an opportunity to develop alternative energy sources, Hughes added.

Charles Hall, a professor at the State University of New York who researches energy and wealth, in graph after graph showed that almost every oil-producing country has reached its peak of oil production.

This is even with a tripling of oil prices over the analysis period, Hall said.

Pieter Tans, a climate scientist at the National Oceanic and Atmospheric Administration who wrapped up the panel, said that while governments and policymakers should still aggressively pursue the goal of reducing greenhouse gas emissions, he did not believe that the most severe IPCC scenario, RCP 8.5, was likely.

From a climate perspective, there is some good news about the likely decline in the growth of fossil fuel production discussed by others at the panel, Tans said.

"It does decrease the chances of catastrophic climate change," he said.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500