CHARACTERISTICS

A stock that intakes and stores carbon is called a "sink". Sinks include the ocean, soil, fossil fuel deposits, and other natural matters, although the Earth's largest sink by far is forests sequesters. Approximately two-thirds of the carbon sequestered on earth is captured by forests. Most plants and crops release much of their carbon at the end of their season, but forests store carbon for decades, or even centuries, making them an excellent means of sequestering large amounts of carbon over relatively short periods of time.

The carbon stored in these sources can be released accidentally or expressly through forest fire or through land-clearing, logging or otherwise changing the status of forest land. Actions can be taken to minimize or to prevent carbon release as a result of such actions. For instance, if a site is cleared and vegetation is burned, most of the carbon will be released into the atmosphere. However, if the site is replanted, or is the wood is used for long-life wood products, the net release of carbon will be much smaller.

Scientists estimate that forests are taking up (sequestering) a significant portion of CO₂–possibly more than 25% of fossil fuel use.

Soils that have been or are used for agricultural purposes offer great potential as a sink for atmospheric CO₂. Agricultural practices can promote carbon sequestration by changing tilling methods, altering land-use, maximizing yield/hectare cultivated and maintaining more continuous vegetation cover.

SIZE:
No limit, except the economic trade-off between land used as a carbon sink versus that for food production, grazing, etc.

FEATURES:
In addition to sequestering carbon, forests generate economic and social benefits: for wood products, wildlife habitat, erosion control, water supply, etc.

COST:
Cost estimates vary: Reforestation costs are estimated at $15-40/ton; Southern Co. estimated costs at $5.50/ton with carbon @ 67 ton/acre. The cost of ocean-enhanced sinks is unknown.

CURRENT USAGE:
Estimated that the ocean sequesters 40,000 GtC/year, by far the overwhelming majority of C sequestered.
Utilities can sponsor local or smaller-scale efforts to increase tree populations in public areas.¹

POTENTIAL USAGE:
Potential for up to 2 GtC/year out of the atmosphere-terrestrial flux of 60 GtC.

CLIMATE CHANGE IMPACT

EMISSION EFFECT:
    

CONDITIONS FOR EMISSIONS MITIGATION:

• Due to land-use changes and tropical deforestation, an estimated 2.6 gigatonnes of C per year are not sequestered.
• Uptake is affected by land-use history, length of the growing season, cloudiness and warm temperature anomalies.
• In Northern forests where soils are thawing, net uptake of CO₂ is canceled by release of gases from deep soils caused by warming.
• When wood is burned for fuel, carbon is released; this can be counteracted by insuring that forests/fuelwood sources are managed for re-growth so that no net emissions will occur.

EMISSION ESTIMATE:
Measurements indicate that a North American forest of primarily oak and maple trees, about 60 years old, sequesters ~2 tons C/hectare/year. Global potential for 24-43 billion metric tonnes of soil C sequestration over a 50-year period through adoption of improved agricultural practices, use of set-asides and conservation buffers on marginal cropland, and restoration of degraded lands.

COST-EFFECTIVENESS:
Relatively low cost, although cost-effectiveness varies by location.

SECONDARY EFFECTS:
Enhanced wildlife habitat and ecosystem benefits can result.

ISSUES ASSOCIATED WITH IMPLEMENTING ACTION

• Standards for baseline determination, additionality, leakage, verification and the potential for perverse incentives to motivate forest management decisions are internationally accepted.
• Need to establish mechanisms to measure, monitor and verify sequestration.
• Sinks must remain for 50+ years for full value of offset to be achieved; potential rebound effect if crops used for fuel or as input to make paper/pulp (energy-intensive industries).
• Land-use issues–some countries are hesitant to commit to preserving timber, etc. indefinitely when land may be wanted for future development.
• There is the possibility that monoculture crops, which are known to sequester carbon rapidly, and thus offer greater short-term carbon storage gains than the previously existing ecosystem, will replace biodiverse heterogeneous forest ecosystems.
• Scientific uncertainties remain: where/how large sinks are, why and for how long sequestration occurs — difficulties in isolating impact of defined geographic area.

RESOURCES

• Through the U.S. Initiative on Joint Implementation (USIJI), several utilities have participated in carbon sequestration projects. American Electric Power (AEP), a large U.S.-based utility, partnered with The Nature Conservancy on a land-use project in Bolivia. The partners have committed to protect and preserve an environmentally sensitive forested area for 30 years, and expect to sequester 14.5 mmtC over the project lifetime. Wisconsic Electric Power (WEPCO) is also working with The Nature Conservancy on a 40-year conservation and forest management project in Belize, expected to sequester 1.3 mmtC over the project lifetime. More information on these and other projects is available at http://www.ji.org.
• Climate Technology Initiative (CTI) under the FCCC Task Force 7–mission is to accelerate international collaboration for R&D in the field of medium- and long-term technologies relating to greenhouse gas capture and disposal.
• IEA Greenhouse Gas R&D Programme, http://www.ieagreen.org.uk

CONTACTS

The Nature Conservancy
Randall Curtis
Arlington, VA
Tel: (703) 841-4864
http://www.tnc.org

Oregon State University
Ted S. Vinson, Ph.D., P.E.
Corvallis, OR
Tel: (503) 737-3494

Reforest the Tropics
Herster Barres
Mystic, CT
Tel: (203) 572-8199

Trexler and Associates
Mark Trexler
President
Oak Grove, OR
Tel: (503) 786-0559
Fax: (503) 786-9859

U.S. Initiative for Joint Implementation
Secretariat
Washington, DC
Tel: (202) 586-3288
Fax: (202) 586-3485
Fax-on-Demand: (202) 260-8677
http://www.ji.org