The world is on the brink of a "golden age" for natural gas, with demand for the low-carbon fossil fuel slated to rise by 50 percent -- as much as demand for coal, oil, nuclear power combined -- over the next two and a half decades, according to a recent report by the International Energy Agency.

Should those trends manifest, however, the world will have little chance of halting global warming at 2 degrees Celsius over preindustrial levels, the limit most scientists say is necessary if runaway climate change is to be avoided.

"We are not saying that it will be a golden age for humanity -- we are saying it will be a golden age for gas," Fatih Birol, lead author of the study "Golden Rules for a Golden Age of Natural Gas" told the BBC.

Driven by increased exploration in North America and China, production of shale gas could triple to 1.6 trillion cubic meters during that period, swelling gas's share of the global energy mix to nearly a quarter by 2035.

Advocates for natural gas often point to its potential as a "bridge resource" -- a low-carbon alternative for baseload power that can displace coal and oil until renewable energy sources like solar and wind become economically scalable. Yet deploying natural gas on the scale projected by the IEA report would mean building infrastructure that locks the world into gas for decades to come, the IEA notes.

The report notes, as well, that "lower natural gas prices lead to slightly higher overall consumption of energy and, in some instances, to displacement of lower-carbon fuels, such as renewable energy sources and nuclear power."

Gas no panacea for global warming
The study projects an overall greenhouse gas increase of 20 percent compared to 2010 levels, slightly lower than projected if the current fuel mix, including coal, were to persist.

"Overall, the projections [in the high-end usage scenario] involve only a small net shift in anticipated levels of greenhouse gas emissions," the study notes.

Those projections see atmospheric carbon dioxide concentrations stabilizing at 650 parts per million, resulting in a temperature rise of 3.5 degrees Celsius above preindustrial levels.

Those conclusions have drawn criticism from environmental groups, including Friends of the Earth and the World Wildlife Fund, which argue that the analysis leaves out the important roles that energy conservation and renewable energy could play in the future.

"We know how to build gas plants, how to get permits. There's a lot of momentum there, obviously," said Marty Spitzer, U.S. climate policy director at the World Wildlife Fund. "But I think we need to have a conversation about this and ask ourselves, just because we have the gas, just because know how to use it, does that really mean we should?"

Spitzer agreed that gas might function as a bridge but only if it could somehow be used without locking the world into several decades of gas-fired infrastructure. "You need baseload capacity to offset things like solar and wind, so there's a good marriage there with gas," he said. "But even then, gas can't just replace all the other fossil fuels as the baseload. We need to be deploying wind, solar, geothermal at the same time."

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