If the measure of President Obama's proposed power plant regulations is their impact on climate change, they would be doomed to failure, according to climate scientists.

Under the U.S. EPA proposal, carbon emissions from the power generation sector would fall by 30 percent below 2005 levels. The reductions would be split among the states, with each state assigned a distinct target by EPA. The power sector contributes 40 percent of the greenhouse gas emissions of the United States, and coal-fired power plants are the sector's biggest emitters.

EPA's proposal is remarkable given the relative paralysis on climate action in Washington, but it would not budge the world's ever-rising emissions trajectory. That's because climate change is a global problem, and addressing it would require concerted action by all nations, heavy investments in carbon capture and sequestration (CCS) and near-zero emissions before 2050.

The new EPA rules as currently structured do not promote CCS and will likely shift the nation toward reliance on natural gas, which is also a greenhouse gas emitter, for power generation, cautioned Myles Allen, head of the Climate Dynamics Group at the University of Oxford.

The reason for climate scientists' pessimism is this: Carbon dioxide persists in the atmosphere for centuries, so today's emissions would trap heat at the Earth's surface well into the future. And at the rate we are emitting, the world would exceed the 2 degrees Celsius (3.6 degrees Fahrenheit) temperature change limit for 2100 that nations aspire to, according to climate models in the Intergovernmental Panel on Climate Change's (IPCC) fifth assessment report.

Curbing emissions from just coal-powered electricity, and in just one country, would not change that reality, said Michael Oppenheimer, a professor of geosciences and international affairs at Princeton University.

"Marginal cuts by the U.S. don't have a long-term overall big effect on the climate," he said. "What has to happen to have a big effect on the global climate is for all the big emitters to get together and decide that they are all going to cut some substantial fraction [of emissions]."

He said that global action, especially from developing nations such as China and India, could be more likely now that the U.S. has indicated its commitment to the problem. But observers of international treaty negotiations remain pessimistic about that prospect (ClimateWire, June 2).

A switch to natural gas won't do

Kenneth Caldeira, an atmospheric scientist at the Carnegie Institution for Science, said EPA's actions have to be the first step, and the agency needs to take similar steps every two years or so. And on top of that, the rest of the world needs to follow the United States' lead.

"But if this is the effort, and that is the end of it, then it's nowhere near the scale of what needs to be done," Caldeira said.

However, EPA's power plant regulations are likely the last major step toward achieving emissions reductions by 2020.

EPA is expecting some states to cut emissions by switching to natural gas for electricity generation, according to senior agency officials on a media briefing. Natural gas combined-cycle power plants are already heavily favored by utilities to the near exclusion of coal, said Joost de Gouw, an atmospheric scientist with National Oceanic and Atmospheric Administration's Cooperative Institute for Research in Environmental Sciences. On a per-megawatt basis, these plants emit just 40 percent of the emissions as coal-fired power plants.

But switching to natural gas for power generation does not solve the climate problem, scientists cautioned. Climate models in the IPCC's latest report indicate that to keep within the 2 C target by 2100, the world would have to emit close to zero, or even negative, quantities of greenhouse gases by 2050.

CCS, in which power plants trap carbon from flue gases and bury it underground, would be the only way to bring emissions to zero, Allen of Oxford said. The EPA proposal does not require CCS for either coal- or natural-gas-fired power plants.

Carbon capture is required

To ensure CCS development by 2050, EPA needs to regulate emissions from all fossil fuels—not just coal—today, Allen said. And immediate action is needed on CCS because any new power plants built now would still be operational in 2050. The energy system of the future would have to be implemented today.

"You would get exactly the same impact and guarantee a climate win, if instead of just targeting coal, the EPA would require a fraction of the carbon content of all forms of fossil energy should be sequestered," he said. "If they did that, job done."

Another potential problem with relying too much on natural gas is that the fuel is primarily made up of methane, a potent greenhouse gas. Studies have suggested that leaks of methane during production from oil and gas wells are so high that the fuel may be no better for the climate than coal. Research into the problem is ongoing.

The EPA-proposed rules apply to existing coal-fired power plants and would be implemented by executive order rather than as law. That means the rule could be changed by successive administrations, which creates regulatory uncertainty.

The rules may even be altered to allow coal back into the energy mix if the U.S. is faced with scarce resources, Allen said.

A step in the right direction?

"If the impact of these cuts is to mean the U.S. burns gas faster, and then goes back to burning its coal reserves in 2030, arguably it will make the problem worse," he said.

Richard Tol, a professor of economics at the University of Sussex, said the less permanent nature of executive orders can discourage investments in power plants, which are long-lasting infrastructure. He pointed to the United Kingdom, where long-term investments in power generation have stalled because climate and energy policy keeps changing "week to week."

"If you have a good reason to believe the rules of the game will change, then you are better off waiting and not investing," he said. "The next president may not agree with whatever Obama has done, and it creates an uncertainty that is very, very detrimental to investors."

Tol, at the same time, praised the EPA regulations as a step in the right direction. Given the humongous scope of the problem, action can seem beside the point, but "that creates a sense of defeatism right?" he said.

"If nobody does anything, then the problem will not go away," he said. "Every little bit will help."

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