The Role of Forest Sinks in a Post-Kyoto World

This feature appeared in the Summer 2006 issue of Resources.

Today, most scientists, as well as the Bush administration, agree that global warming is indeed occurring and that it is a significant problem. The question of the efficacy of the Kyoto Protocol as a remedy, however, is another story. While some European countries are on schedule to meet their emissions targets, others are not. Two of the largest carbon emitters, China and India, are not even required to comply--they have no carbon targets. Two others, the United States and Australia, have chosen not to ratify the protocol, and now Canada, which did ratify, has announced that it does not expect to comply. But even if all the global Kyoto Protocol targets are met, the global temperature in the year 2100 will be only about 0.3°C lower than "business as usual," because just 7-10 percent of the expected temperature rise would be prevented if the Kyoto targets were met.

Global Carbon Sinks: Some Basic Concepts

Global carbon is held in a variety of different "stocks." Natural stocks include oceans, fossil-fuel deposits, the terrestrial system, and the atmosphere. In the terrestrial system, carbon is sequestered in rocks and sediments; in swamps, wetlands, and forests; and in the soils of forests, grasslands, and farmland. About two-thirds of the globe's terrestrial carbon, exclusive of that sequestered in rocks and sediments, is sequestered in the standing forests, forest understory plants, leaf and forest debris, and forest soils. In addition, there are some nonnatural stocks, such as long-lived wood products (typically wood construction and furniture) and waste dumps that constitute a separate, human-created carbon stock.

Forests in Transition Forests are constantly in transition, being cleared for agriculture and often subsequently replanted or abandoned and left to grow in, for example. The Kyoto Protocol accounts for this in Article 3.3, which calls for the maintenance of forests by afforestation, reforestation, and controlling deforestation (ARD).

Deforestation occurs when forestland is cleared and reforestation does not take place. Commonly, land clearing is associated with the permanent conversion of forestlands to other uses, such as croplands, pasture, or development. When forestland is converted to some other use, there is a net loss of carbon in the terrestrial stock since most other land uses will sequester less carbon than the forest. Under these circumstances, net carbon transfers occur. If the site is cleared and the vegetation burned, most of the carbon is released into the atmosphere. However, to the extent that the vegetation is converted into long-lived wood products or substituted for fossil-fuel energy, only a portion of the carbon in the forest will be a net release into the atmosphere.

The creation of a forest on land never forested or not forested for a very long time is called afforestation. Often the distinction between afforestation and reforestation blurs as the period during which the forest has been absent from the land lengthens. Afforestation occurs when forests are established on grasslands never previously forested. It also may be said to occur as lands once in forests but which have been in agriculture for long periods of time, as in parts of the U.S. South, are converted into forests, due to either natural processes or tree planting. On afforested lands, the additional carbon stored in trees and other components of the forest ecosystem constitutes a net addition to the terrestrial forest stock.

Forest Sequestration and the Kyoto Protocol

Historically, humans have contributed to carbon dioxide emissions in two ways: by burning fossil-fuels and converting forestlands to other uses. Initially, land-use changes (deforestation) were the principle source of carbon emissions. However, starting in the 20th century, fossil-fuel emissions rose rapidly, while emissions due to deforestation gradually declined. One way to begin to address the issue of increasing carbon emissions is to maintain and increase the stock of sustainably managed forests.

		Although it is well known that the world's tropical forests are declining, it is less widely recognized that the world's temperate and boreal forests have been expanding. Recent UN Food and Agricultural Organization estimates indicate a net global deforestation rate--that is, the conversion of forestland to other uses--for 2000 through 2005 of 7.3 million hectare (ha) per year. This is a reduction from the 8.9-million-acre net annual deforestation of the 1990 to 2000 period, when deforestation of natural forests at 14.1 million ha per year was partially offset by an afforestation rate of 5.2 million ha per year. So, while the tropical forest carbon stock has become smaller, the temperate and boreal forests have been expanding.  The Kyoto Protocol recognizes the efficacy of forests and sustainable management as a vehicle for addressing climate change in Article 2, which states that each party in Annex 1 (major industrialized nations) shall establish or expand policies and measures that promote sustainable forest management practices. Additionally, according to Article 3.3, afforestation and reforestation credits are obtained, while deforestation is associated with debits. Article 3.4 provides credits for increases in the carbon sequestered by forest management.

But the protocol fails to take full advantage of the potential of forest sinks. Looking toward a post-Kyoto world, how might the role of forest sequestration be expanded to more fully address climate change?

Several northern countries--including France, Portugal, Japan, China, some Eastern European countries, and the United States that are experiencing positive net biological growth--have a wide interpretation of forest management and of forests that are eligible for credits. Although these forests are sequestering large amounts of carbon, much of this would probably occur without a carbon program. The question is how much of the additional carbon reasonably can be viewed as additive, in the sense that they would not have occurred under business as usual.

Under Kyoto, European Union countries were given credit for 15 percent of the net growth of their managed forests, with no credits or debits associated with unmanaged forests. This approach assumes that active management is responsible for 15 percent of the incremental addition in forest growth. However, exceptions--based on political, not scientific, considerations-- providing for larger amounts of credit were negotiated for some countries, such as Russia. A question for a future agreement is how much sequestration would be allowed for various countries from forest management.

In addition, as it now stands, the protocol does not give credit for protecting existing forests, although loss of forests can generate debits for countries with carbon targets. This issue becomes more complex if the countries without carbon targets undertake sequestration programs, as with the Clean Development Mechanism (CDM), in cooperation with industrial countries. Furthermore, if the current system were applied to the next compliance period, these countries could incur carbon debits for forest losses that might occur beyond a base period yet to be determined.

One approach for initially involving tropical countries might be to allow them positive carbon credits for reducing their rates of deforestation below a baseline level. The baseline could be constructed by using the estimate of the forest and its carbon at some time point. Alternatively, a baseline trend might be constructed by projecting the forest carbon through time. Credits could be provided for amounts sequestered in excess of baseline levels. Care must be taken, however, in establishing the baseline. The smaller the area involved, the larger the likely "leakage," that is, the shifting of emissions out of one geographical area and into another. When this happens, credits are obtained for emissions reductions in the one area, while emissions increases that occur simultaneously in another area do not receive debits.