About 55 percent of U.S. homes get their heat from natural gas, accounting for about 7 percent of our emissions, and this combustion source represents another opportunity for reductions. As with electric appliances, the DoE has issued (and continues to update) standards for furnaces and water heaters; tightening them could lower emissions while offsetting increased energy costs that may result from conversion to renewable sources (or from a carbon tax, if that ever happens). And although the federal government cannot require building code improvements, which is handled at the state and local levels, it can encourage them, which is another chance to lower both emissions and utility bills.
Transportation accounts for the most emissions after those associated with energy utilities—about 29 percent of the total. Obama’s National Highway Traffic Safety Administration issued fuel economy standards for light-duty vehicles (aka cars) in May 2010 that will reduce the amount of oil used in the United States by more than what we buy from Saudi Arabia. It was such a huge leap, in fact, that it’s unlikely he’ll be able to press for more fuel-economy improvements in automakers’ consumer fleets during his second term. But the EPA has additional authority to effect reductions in cars’ tailpipe emissions regardless of their mpg. And the efficiency requirements enacted in 2010 didn’t cover vehicles like delivery trucks and 18-wheelers; given the strong buy-in from industry on the requirements for cars, upping the larger vehicles’ fuel economy should prove doable if the administration chooses to prod the industry in this direction.
Aircraft account for 2 percent of total emissions but because the bulk of their release happens high in the atmosphere, they have a higher impact on climate change than do earth-bound engines. The EPA can write emissions standards for new planes, but aircraft turnover is slow; the greater chance for significant reduction in the short-term is through operational changes like shortening routes to diminish fuel consumption, requiring aircraft to shut down engines at the airport to reduce idling, and more towing during ground taxiing.
Diesel-burning barges that move goods around the globe, the EPA found, could be targeted for a reduction of as much as 20 million metric tons of carbon, but since marine shipping is a very international market, how much the United States can affect it is questionable.
Factories, refineries, and other industrial facilities—especially cement kilns—account for about 15 percent of emissions, and the Obama administration has a good deal of leeway here. The EPA can, under the Clean Air Act’s “New Source Performance Standards,” require new or upgraded facilities that produce pollution to use the “best demonstrated technology” to limit emissions. (This is the same method that would directly target individual power plants.)
Agriculture produces about 7 percent of emissions, but there’s not much opportunity here without help from Congress. Policies enacted through the Farm Bill, which is due for renewal, could do more than the Deptartment of Agriculture or Forest Service on their own because those agencies would need an increase in their budgets—which would have to come from Congress—to be effective.
One of the smallest sources of greenhouse gas emissions is nevertheless disproportionately concerning to environmental policy analysts: hydroflourocarbons. These gases are used in air conditioners and are a “significant area of growth,” according to Lashof. The Montréal Protocol, which phased out ozone-depleting gas propellants, is currently being renegotiated to include HFCs, but since most U.S. air conditioners now in use rely on them, and venting the gas is easier and cheaper than collecting it (as repair personnel are already required to do, though enforcement is lax), they are likely to remain around 2 percent of emissions regardless of President Obama’s efforts.
Still sounds like a lot he can do though, right? Sort of. When you tally it all up, even if the president acts aggressively, it’s unlikely the United States will reach the 17 percent reduction from 2005 levels pledged (but not required) by the 2010 Copenhagen Accords. And that non-commitment is significantly less than the 20 percent below 1990 levels pledged by the European Union or the 25 percent below 1990 levels Japan has promised.
The sad fact is that without Congress’ help, the president can’t get the atmospheric concentration of greenhouse gases to a level that won’t cause major problems in the lifetime of today’s first-graders. “The scope of the problem,” says Nicholas Bianco of the World Resource Institute, who has studied the U.S. executive’s power over emissions, “is too enormous not to have Congress taking an active role. The science is quite clear that we cannot delay.”