Does planting trees reduce climate change ?

Since 1750, it is estimated that about 2/3rds of anthropogenic CO2 emissions have come from fossil fuel burning and about 1/3rd from land use change (IPCC 2007). Therefore, deforestation is a major source of carbon emissions. Stopping deforestation and starting reforestation can act as an important sink of atmospheric CO2. However, forests can not grow infinitely and the carbon flux from above ground biomass to the soil is not effective enough. Moreover, climate change alone will tend to suppress land carbon uptake, increasing the fraction of anthropogenic CO2 emissions that remain airborne and producing a positive feedback to climate change.*

The Kyoto protocol recommends that we should all plant more trees. While more trees may be good for the environment lower latitudes, the reverse is true at higher latitudes where land is covered with snow most of the year. This is because snow reflects more solar energy back into space. As these northern lands become forested again due to global warming and the retreat of the glaciers, more solar energy will be absorbed and converted into heat and thereby creating a positive feedback.

After all, focusing only on trees is risky because of the possibility of forest fires and it may take more trees to absorb one tonne of carbon from the atmosphere than one would think (see pdf).

Source:

*Denman, K.L. et al., 2007: Couplings Between Changes in the Climate System and Biogeochemistry. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.