Without the climate policies called for in President Obama's second-term agenda, the United States would fail to meet a national goal of curbing greenhouse gas emissions 17 percent below 2005 levels by 2020, the State Department said in a report.
Emissions will fall 5.3 percent below 2005 levels by 2020 based on projections that account for policies in place by September 2012, according to the report, which was completed as part of the United Nations Framework Convention on Climate Change.
"We know we must do more, and believe me, we are," said Secretary of State John Kerry. "President Obama's climate action plan will keep the United States on track to reach our goal."
The U.S., with Obama's recent emphasis on climate, is attempting to position itself as a leader ahead of international negotiations in 2015 in Paris. Nations there will try to secure a treaty to cut emissions enough by 2020 to avert a 2 degree Celsius rise in global temperatures by the end of the century — a goal that climate scientists warn is slipping away.
Still, implementation of the U.S. rules could become tricky. They'll undoubtedly face legal challenges, and some climate experts are concerned political sensitivities might take some of the bite out of the rules.
Structurally, though, changes in the energy arena are helping the U.S. cut emissions.
Cheap and abundant natural gas pushed emissions to their lowest level in nearly 20 years as more power plants switched to that fuel instead of coal, which is twice as carbon-intensive. Cars are becoming more fuel efficient and will continue that trend as automakers work toward new standards finalized in August 2012 that require cars to get 54.5 miles per gallon by 2025. Solar panel prices also have come crashing down, and the wind industry, with the help of a 2.3-cent-per-kilowatt-hour tax credit, installed a record 13.1 gigawatts of capacity in 2012.
As such, emissions have fallen 6.5 percent below 2005 levels, the report said. The industrial sector saw the biggest decline, at 11.2 percent, followed by 10 percent for electricity, 8 percent for transportation, 7.3 percent for residential and 6.5 percent for commercial users.
But they will rise "gradually" between 2011 and 2020, owing to a 26 percent population increase and a 69 percent bump in gross domestic product through 2030, the report said.
One area for improvement is wider and more rapid adoption of technology that emits fewer greenhouse gases, the report noted. Gains in areas such as energy efficiency could tamp down demand even as the population grows, it noted.
Short of that, further regulatory measures could be in the offing.
For example, the report identified energy-related carbon dioxide, methane and hydrofluorocarbons — a short-lived, highly potent heat-trapping gas used in refrigerants — as areas of potential reductions.
The Obama administration is already looking to address carbon through the power plant regulations, and it's working on curtailing hydrofluorocarbons through a bilateral agreement with China.
Methane, however, is a different story, as the Environmental Protection Agency doesn't directly regulate the gas.
"[A]ssessing the potential achievable reductions of methane emissions in 2020 involves considerable uncertainty," said the State report, which noted several agencies are working on a coordinated strategy to address methane.
Environmental groups say that's a problem -- they contend that methane leaks from hydraulic fracturing, or fracking, could negate the climate benefits of relying on natural gas for the nation's energy. Experts suggest a 3 percent leakage rate would erase the climate positives of natural gas.
Fracking involves injecting a high-pressure mixture of water, sand and chemicals into tight rock formations to unleash hard-to-reach hydrocarbons. It's unleashed a domestic energy boom, but has also invited concerns about groundwater pollution.
The oil and gas industry would likely push back against a regulatory approach, as it says that would make fracking costlier.
EPA Administrator Gina McCarthy, for her part, said recently that the agency is constantly reviewing its methane emissions data when confronted with a Harvard University study that said methane emissions were at least 1.5 times higher than EPA estimates.
"There are challenges associated with looking at regulating methane itself, but we are certainly looking at every tool available to the EPA, as the president indicated we should," she told reporters last month at a Washington event hosted by the left-leaning think tank Center for American Progress.