Do Recent Scientific Findings Undermine the Climate Benefits of Carbon Sequestration in Forests?

Recent scientific papers document previously unknown or under-reported methane emissions and water trade-offs that could reduce the benefits from terrestrial carbon sink practices such as reforestation and plantations. This Nicholas Institute report examines the policy implications of these findings. The report is a consensus document from a roundtable of top experts convened at the Institute earlier this year. Recent scientific papers document previously unknown or under-reported methane emissions and water trade-offs that could reduce the benefits from terrestrial carbon sink practices such as reforestation and plantations. This Nicholas Institute report examines the policy implications of these findings. The report is a consensus document from a roundtable of top experts convened at the Institute earlier this year.

Author(s): Lydia Olander

Published: April 2006

download: consensus document(.pdf) >

A key feature of global warming policy has been the role of carbon sinks in offsetting our greenhouse gas emissions. In practice carbon sinks are forests and agricultural lands that remove carbon dioxide from the atmosphere and sequester it in plant matter and soils. In nearly every policy arena, carbon sinks are used to enhance the economic efficiency of mitigation by providing more flexible compliance options. For instance,the Kyoto Protocol, the international accord on reducing greenhouse gas emissions, allows the use of carbon sinks through afforestation, reforestation, and reduced deforestation to help meet a country’s greenhouse gas reduction targets. Carbon sinks play a prominent role in greenhouse gas reduction programs in the U.S., as part of programs such as the DOE’s 1605(b) voluntary registry, California Climate Registry, and the Regional Greenhouse Gas Initiative of the Northeastern states.

Two recent papers in the scientific literature have generated speculation regarding the benefits of terrestrial carbon sinks. One paper, led by Frank Keppler from the Max Planck Institute found that plants emit significant amounts of methane, a potent greenhouse gas. Another study, led by Robert Jackson of Duke University found that plantations can reduce stream flow and increase salinization of soils more than previously thought. Some media and interested parties have speculated that this research calls into question the value of carbon sequestration from trees and plants as a climate change mitigation strategy. Others viewed this speculation as far overblown.

What did the research say? What do scientific experts think about its significance? And should current policy be altered as a result?

To answer these questions a group of experts gathered at Duke University. They assessed the science and its implications and came to the consensus discussed in this document.