Forest Carbon in the United States: Opportunities & Options for Private Lands
By Laurie A. Wayburn, Jerry F. Franklin, John C. Gordon, Clark S. Binkley, David J. Mladenoff, Norman L. Christensen, Jr.
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Executive Summary
The United States has a highly significant opportunity to reduce its net emissions of carbon dioxide (CO2) through actions on private forests in three areas:
- Reducing forest loss
- Increasing reforestation of former forests
- Increasing forest age
Actions in these three areas could permanently increase forest carbon stocks in the US by millions of tons annually at a cost per ton equivalent to the lower end of the range of mitigation costs.
Forest Extent and Carbon Retention
Forests occupy one-third of the US land mass (747 million acres), with private ownership on almost two-thirds of that area (424 million acres). Private forests are the most productive—and threatened—forests in the country. Their state of carbon accumulation or release has a major impact on the US carbon balance. When forests accumulate and hold carbon (sequestration), they contribute to lowering emissions overall, acting as carbon “sinks” or reservoirs. When forests are disturbed through harvest or conversion to other land uses, they release carbon, adding to emissions overall. From the net atmospheric carbon balance, a molecule of CO2 removed from the atmosphere is equivalent to not releasing a molecule of CO2 to the atmosphere.
Whether these forests accumulate and hold carbon, release carbon, or are lost entirely as carbon sinks will be a major determinant in how quickly and cost effectively the US can meet its goals to reduce carbon emissions.
Currently, the US counts on forests to help reduce its net total emissions; for example, forests sequestered 310 million metric tons of carbon (MMT CE) in 1999. However, this amount was less than the prior year and continued a decline in stores from the past five years. When forests store less carbon, they are releasing more. The two major causes of decline in stores of forest carbon are forest conversion and loss and the increase of harvest versus the amount of growth on private forest lands.
Forest cover in the US has declined by one-third to one-half its extent since European settlement. While there has been considerable re-growth of US forests since the early to mid-1900s, especially in the Northeast and Southeast, the US is nevertheless currently losing forests at an increasing rate, with lost acreage in the five years from 1992 to 1997 estimated to be twice as great as in the 10 preceding years, 1982-1992. Further, land in forest use is projected to continue to decline as competition for land for development continues to increase. As forests are lost, particularly older forests, so too are carbon reservoirs, as older forests accumulate and store more carbon than younger ones.
In addition to forests lost to development, increases in timber harvests outstripped the amount of tree growth on private forests in the 1980s and 1990s, extending a trend from the 1960s. As a result, the US is beginning to lose more carbon in private forests than it is accumulating, especially in faster-growing softwoods and the most productive forest regions of the country, the Pacific Northwest and Southeast. Overall, the US lost 11.5 million acres of existing forest between 1982 and 1997, and the average age of forests on private lands declined in this period as well. The results include diminished forest habitat and watershed values as well as decreased carbon stocks. Since 1990, the US has stored less forest carbon each year. That trend is projected to continue to 2020 through the loss and unsustainable harvest of private forests.
Increasing Carbon Stores
While the total amount of forest carbon storage is declining, especially on private lands, it is not irreversible. The US has the opportunity to increase net forest carbon stores on private forests significantly by addressing the causes of these trends and encouraging landowners to alter prevailing business-as-usual practices through changes in management actions consistent with increasing carbon stores. These actions include preventing forest loss by conserving current forestland, reforesting former forest areas, and increasing average forest ages. With such actions, forest carbon stores could increase in the US by hundreds of millions of tons during the next several decades and play a significant role in diminishing net US emissions of CO2.
These changes in management depend on the development of a new market for forest carbon sequestration services. Value added to standing timber in the form of carbon credits, if sufficiently valued, could encourage private forest owners to make the management decisions that would reduce CO2 emissions and increase carbon stores. To be an effective economic incentive, the price of carbon needs to be at least $20/ton C ($5.45/ton CO2). This enables carbon to provide some incremental value to landowners, resulting in either retention of land for forest or retention of trees during harvest. At prices of $100/ton C ($27.25/ton CO2) and greater, the value of carbon alone begins to pay landowners to hold land and increase forest age, competing directly with returns from development and short rotation timber harvest. However, carbon values are likely to have the most significant impact when used to pay for partial interests: keeping the land in timber production, but changing forest management and paying part of the cost to keep land from conversion. In most cases of high development or very high timber values, carbon values must be at least $150/ton C ($40.87/ton CO2) to be competitive.
To create this marketplace, the US needs to establish some essential infrastructure. This includes:
- Formally identifying carbon rights
- Developing a standardized carbon accounting system that includes both credits and debits and adjusts appropriately for risk
- Establishing a credible registry at the federal and state levels
Accounting for forest carbon should follow the same principles, such as additionality (crediting above business-as-usual), permanence, and accuracy levels, established for other carbon emissions sectors, such as energy and transportation. Standard accounting rules for a forest carbon market must:
- Include both debits and credits
- Discount appropriately for risk
- Discount for less-than-permanent stores
- Require accuracy to the same level as for other emissions sectors
Increasing net and permanent forest carbon sequestration while decreasing forest carbon emissions is clearly a meaningful piece of the set of actions that the US needs to pursue to reduce global warming. With a transparent and credible accounting system, a robust market for long-term and verifiable US forest carbon credits would yield a significant new revenue base for private forest landowners and lower the cost of permanent emissions reductions for carbon producers. It would also lead to substantial benefits for biodiversity, watershed values, open space protection, and long-term, sustainable domestic timber supplies. A carbon market would promote restoration of forest timber inventories, and therefore carbon, on private forests in the US, leading to more sustainable forest economies overall.
(c) 2000 Pacific Forest Trust, Inc.