Protecting climate with forests
Robert B. Jackson, James T. Randerson, Josep G. Canadell, Ray G. Anderson, Roni Avissar, Dennis D. Baldocchi, Gordon B. Bonan, Ken Caldeira, Noah S. Diffenbaugh, Christopher B. Field, Bruce A. Hungate, Esteban G. Jobbagy, Lara M. Kueppers, Marcelo D. Nosetto & Diane E. Pataki
Climate mitigation policies often only take into account their effect on atmospheric CO2. However, implementing projects such as widespread afforestation would have many biophysical effects as well that could change temperature even more than carbon dioxide. Ignoring these effects could lead to the implementation of projects that are in fact counter productive.
Jackson, R. B.; Randerson, J. T.; Canadell, J. G.; Anderson, R. G.; Avissar, R.; Baldocchi, D. D.; Bonan, G. B.; Caldeira, K.; Diffenbaugh, N. S.; Field, C. B.; Hungate, B. A.; Jobbagy, E. G.; Kueppers, L. M.; Nosetto, M. D.; Pataki, D. E., 2008. Protecting climate with forests, Environmental Research Letters 3 (4):44006.
Policies for climate mitigation on land rarely acknowledge biophysical factors, such as reflectivity, evaporation, and surface roughness. Yet such factors can alter temperatures much more than carbon sequestration does, and often in a conflicting way. We outline a framework for examining biophysical factors in mitigation policies and provide some best-practice recommendations based on that framework. Tropical projects—avoided deforestation, forest restoration, and afforestation—provide the greatest climate value, because carbon storage and biophysics align to cool the Earth. In contrast, the climate benefits of carbon storage are often counteracted in boreal and other snow-covered regions, where darker trees trap more heat than snow does. Managers can increase the climate benefit of some forest projects by using more reflective and deciduous species and through urban forestry projects that reduce energy use. Ignoring biophysical interactions could result in millions of dollars being invested in some mitigation projects that provide little climate benefit or, worse, are counter-productive.