Tackling climate change means curbing emissions from smokestacks, but also expanding our forests

Last week, in his State of the Union address, President Obama reaffirmed his commitment to tackling climate change to the American people:

“Over the past eight years, the United States has reduced our total carbon pollution more than any other nation on Earth. But we have to act with more urgency – because a changing climate is already harming western communities struggling with drought, and coastal cities dealing with floods. That's why I directed my administration to work with states, utilities, and others to set new standards on the amount of carbon pollution our power plants are allowed to dump into the air. The shift to a cleaner energy economy won't happen overnight, and it will require tough choices along the way. But the debate is settled. Climate change is a fact. And when our children's children look us in the eye and ask if we did all we could to leave them a safer, more stable world, with new sources of energy, I want us to be able to say yes, we did.”

Days earlier, with the release of the United States Climate Action Report 2014 (CAR), the Obama Administration reported on these efforts to the international community, detailing the actions the US is taking to address climate change, as well as our progress towards hitting emissions reduction targets adopted at the 2009 international climate conference in Copenhagen. There, President Obama committed to reducing US economy-wide emissions of greenhouse gases (GHGs)—the heat-trapping gases responsible for the warming of our planet—17% below 2005 level by 2020.

The good news is that as my colleague discussed here, we are on track. If implemented effectively, the President’s Climate Action Plan—the policy approach the administration is using to meet this commitment—would mean the US would successfully hit its emissions reduction target. However, integral to this effort is ensuring that all carbon emissions are counted, including those from our forests and other lands.

Our lands can be huge carbon “sinks”, absorbing large amounts of carbon dioxide (CO2) out of the atmosphere and storing it safely in forests and soils. But when land use change involves clearing forests to make way for agriculture or development—or when trees are cut and burned to produce energy—they can also become major sources of carbon emissions. 

As confirmed in the CAR, US forests today are an important net “sink” for atmospheric carbon. This is no small tool in our fight against climate change. Forests currently account for the vast majority of net carbon sequestration among all land uses in the US.  In 2011, the land use, land-use change, and forestry sector absorbed a net of 905.0 teragrams (Tg) of CO2—an offset of more than 17% of our total fossil fuel emissions. According to the report, this is largely the result of net forest growth and increasing forest area, as well as a net accumulation of carbon stocks in harvested wood pools. 

But future trends are less certain. According to the report,

“There are indications that in the long-term, US forest carbon stocks are likely to accumulate at a slower rate, and eventually may decline as a result of forestland conversion and changes in forest growth related to climate change and other disturbances. The exact timing of these changes is uncertain, but US forests are unlikely to continue historical trends of sequestering additional carbon stocks in the future under current policy conditions.”

We need our forests to continue expanding and sucking carbon out of the atmosphere.  Unfortunately, these forecasted changes in biomass stocks likely reflect some degree of non-sustainable harvesting of woody biomass—plant material like trees and forest residues—to burn for bioenergy production.

In search of an alternative to coal and other fossil fuels, power companies are increasingly looking to biomass as a fuel source. This new demand for wood—reflected in the explosive growth of the wood pellet industry in regions like the US South—now threatens the health of some of our most carbon and ecologically rich forests. 

Biomass energy companies argue that because trees can grow back, biomass should be considered a “carbon neutral” fuel source. In other words, when biomass is burned in power plants, they want all the carbon emitted from the smokestack effectively ignored, based on the assumption that new trees will grow back and recapture it. 

Last summer, a federal court rejected that argument. So did an earlier report by the EPA’s own Science Advisory Board.

Now, the Environmental Protection Agency is in the process of developing rules to account for this “biogenic CO2”—the CO2 emitted when power plants burn biomass.  These accounting rules are part of the larger effort to control carbon emissions from power plants, a key component of the President’s climate plan highlighted in his speech. [In the US, existing electric power plants emit about 2.4 billion tons of CO2 each year, or roughly 40% of the nation’s total annual emissions—our single largest source of climate-changing pollution. Cleaning up these plants is central to hitting our targets and protecting the health of our communities, children, and planet.]

As I discussed here, there is no scientific justification for EPA to ignore the carbon emitted by biomass-burning plants. This is carbon that was isolated from the atmosphere before being burned for energy and its emission has the same heat-trapping impact as the fossil carbon released when we burn coal. As we account for our national GHG emissions—and track our progress towards meeting our emissions reduction targets—that carbon loss must either be counted when trees and other biomass feedstocks are harvested or it must be counted at the smokestack when biomass is burned for energy. Ignoring it risks compromising the very goals the President set forth. In could mean we clamp down on carbon pollution from burning coal, but end up increasing carbon emissions from our forestlands and other terrestrial carbon sinks.

Done right, electricity generation fueled by short-rotation crops, wood waste and reclaimed wood, and timber harvest residues (tops and branches) has the potential to reduce carbon emissions within a short time. But we need rigorous biomass carbon accounting rules to guide the market towards these low-carbon sources of biomass and away from the highest carbon biomass—in particular, whole trees.

President Obama’s climate plan shows that we can take strong domestic action to curb climate pollution and meet our emissions reductions targets using existing US law. But to do so, both cuts to GHG sources and expansion of carbon sinks will be critical. The administration must discourage any biomass consumption for energy production that leads to a net reduction in the amount of carbon stored in forests and other lands. EPA should therefore ensure that its regulation of carbon emissions from power plants accurately accounts for the carbon emitted when biomass fuels are burned. Doing so will support a biomass energy industry that demonstrably cuts carbon pollution and protect our vital land-based carbon sinks.