COP-6, the sixth Conference of the Parties to the United Nations Framework Convention on Climate Change, recently got underway in The Hague. How to handle forests is a key item on the agenda. The Convention’s Kyoto Protocol limits the green house gases developed countries can emit. When they calculate whether they have met their carbon targets, these countries must take into account the effects of afforestation, deforestation, and reforestation. The Protocol also set up a ’Clean Development Mechanism’ that allows developed countries to meet part of their commitments by paying developing countries to reduce their own carbon emissions. For instance, developing countries might cut emissions by substituting wind power for diesel-fueled electricity generation. What’s at issue is whether developing countries can also get credit for reducing emissions by planting forests or averting deforestation.

Proponents of this approach argue that it can finance forest conservation and rural livelihoods while lowering the cost of meeting the Kyoto objectives. Skeptics claim it is more difficult to monitor and verify how forestry projects affect carbon stocks than in the case of energy projects. They also assert that whereas energy projects permanently reduce carbon emissions, forestry projects only store carbon for limited periods. Hence they say countries should not be allowed to use forestry projects to offset carbon emissions from other sources.

’Evaluating carbon offsets from forestry and energy projects: How do they compare?’ by Kenneth Chomitz, at the World Bank, evaluates these issues. Chomitz concludes that energy and forestry projects face similar difficulties demonstrating that they really reduce net carbon emissions and measuring by how much. In both cases it is hard to assess what might have happened without the project or how changes in one location affect emissions elsewhere. For many forestry projects and some energy projects it will cost much less per ton to measure carbon stock changes in large projects than in small projects.

Forestry and energy projects do differ significantly with regard to permanence. A real risk exists that carbon sequestered in a forest today will later be released back to the atmosphere. Chomitz discusses various ways to handle this. Developing countries could promise to reduce their future energy-related emissions if the carbon fixed in their forests gets released. They might also issue a limited number of permits to deforest in a region. That would ensure that the carbon stored in the region’s forests would always remain above a fixed level. People who wanted to reduce emissions could purchase these permits and retire them, thus reducing total carbon emissions. Or, some credit might be awarded for each year a ton of carbon is sequestered. That would postpone damages from climate change and give the world more time to find other ways to protect its forests and to learn to adapt to climate change.