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Science and Politics: Carbon Neutral Wood and Land Use Changes

There is a paradox inherent in producing energy by burning wood in order to slow global warming. On one hand, wood does have a better emissions profile than fossil fuels. On the other hand, harvesting wood reduces the amount of carbon sequestered in forests. Because of this paradox, significant controversy arises whenever the carbon footprint of wood bioenergy is discussed.

Currently, the Kyoto Protocol, the European Union’s cap and trade legislation and the proposed (though far from law) American Clean Energy and Security Act of 2009 all classify bioenergy as carbon neutral. An article in a late October issue of Science called this classification into question.

According to the group of scientists that wrote "Fixing a Critical Climate Accounting Error," wood-based bioenergy can only be classified as such because current systems do not account for either the emissions created when bioenergy is used (emissions from “tailpipes and smokestacks”) or changes in emissions (either positive or negative) when biomass is harvested or grown. As a result, they argue, the rules defining biomass energy as carbon neutral are nothing but an accounting gimmick that will incentivize bioenergy and lead to catastrophic land use changes.

After reviewing the article, a few things struck us.

  • The article looks at harvesting forests out of context. It appears to assume that existing forests are being cut down strictly for energy production, and that all the carbon released as a result should be included in the carbon footprint of the energy produced.

Existing forests in the U.S. are not now and will likely never be harvested solely or even primarily for energy production. Only 13 percent of the typical harvest is in-woods fuel, which is then used to produce energy. This 13 percent is a by-product of harvest for other purposes—manufacturing wood and paper products, specifically. If these higher value products weren’t being harvested, no forest biomass would be available for energy production.

 Even harvested timber continues to sequester carbon. The American Forest and Paper Association (AF&PA) estimates that “ Approximately one-third of the carbon in wood harvested for the industry ends up in long-lived products such as lumber, wood-based panels, books, and archived paper and is stored in some cases for decades, even centuries.” Everything made from wood or paper continues to store carbon for some period after it is produced.

  • “Bioenergy reduces greenhouse gas emissions only if the growth and harvesting of the biomass for energy captures carbon above and beyond what would be sequestered anyway and thereby offsets emissions from energy use.”

Measuring “above and beyond what would be sequestered anyway” is complex. Certainly, starting with only that amount of harvested material—the limbs, leaves, bark and other logging residues—that is actually used to produce energy would be necessary.

Calculating how much carbon this material might have sequestered using growth patterns would be unnecessary here since in-woods biomass, if not removed from the forest after harvest, lays on the forest floor and begins to decompose and release greenhouse gases into the atmosphere immediately.

Biomass harvest on public lands will be done as part of fire and disease prevention programs. Fires and insect infestations cause premature death in forests, so removing this material actually saves forests so they can sequester carbon longer.

At a certain age, the amount of additional carbon trees absorb levels off. Younger trees replanted after harvest absorb carbon more quickly.

  • The authors site studies that quantify how the rules as they are currently written incentivize land clearing. These studies — with their gloom and doom results — suggest that ambitious control of carbon emissions will produce devastating consequences — anywhere from 60 percent of the world’s forests being displaced by 2050 to “virtually all” forests disappearing by 2065. (Links to these studies can be found below.)

Forest biomass is only harvested in association with the harvest of higher value forest products, such as sawtimber or pulpwood. Regardless of carbon emissions standards, homes will be built, paper will be produced, and products such as furniture, kitchen cabinets and wood flooring will still be in demand. These demand factors will add a countervailing influence in markets, precluding the displacement of forests. The value of sawtimber will make it more likely that forest landowners will replant trees rather than convert their land to energy crops after harvest.

When deforestation was a significant problem in the U.S. in the 1990s, action was taken to reverse the trend and deforestation was halted. Now, the number of forested acres in the U.S. is stable or growing. In a country that has blocked the building of nuclear electricity facilities, off-shore drilling and even wind and solar farms, this trend is unlikely to revert back to massive deforestation, regardless of carbon emissions reduction targets. In fact, the Department of Energy has made it clear that they support sustainable bioenergy and that they consider land use conversion when determining sustainability.

Conversion of “virtually all” forests to energy crops is unlikely, due to terrain and soil issues. Steep slopes that often characterize forests are unsuitable for any type of agricultural production. Sandy coastal soils like those in the U.S. South that are perfect for growing pine are unlikely to support these crops as well, at least without the level of intensive management that would make doing so cost-prohibitive.

Forest landowners are not farmers. They own forests because they use the land recreationally or generate income from hunting leases, because forests are low maintenance, and because they want to be able to pass their land on to future generations. Surveys of forest landowners suggest low interest in the goals that would lead to large-scale conversion of forests in the U.S.

Carbon sequestration in forests is one of the most significant tools we have for controlling climate change. To suggest that forests will be allowed to go the way of oil and other fossil fuels, thereby destroying the world’s most effective carbon sink, defies logic.

Perhaps a better strategy for the long term would be to incentivize the maintenance of forests, as well as reforestation or afforestation projects worldwide. Forest landowners in the U.S. cannot qualify carbon sequestration projects under existing carbon trading schemes. Forest landowners in Brazil, however, are eligible for carbon credits.

Studies on Effects of Bioenergy on Land Use:

Implications of Limiting CO2 Concentrations for Land Use and Energy

Unintended Environmental Consequences of a Global Biofuels Program

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