In Depth

The Forests and Climate Change

The Forests and Climate Change

Climate change has created a new imperative to protect forests, and tropical forests in particular. The Intergovernmental Panel on Climate Change (IPCC) estimates that deforestation contributes 15 to 20 percent of global greenhouse gases (GHG) emissions1. Because trees absorb and store carbon, healthy forests are critical to mitigating climate change.

Healthy forests also absorb more carbon than unhealthy forests. Sustainable forest management practices (including fire and disease prevention, better growing conditions, healthier trees and more efficient stand rotation) produce trees that help further reduce GHGs.

Global anthropogenic greenhouse gas emissions, 2004

Source: IPCC (2004)1

 

Deforestation is occurring at a rate of over 13 million hectares per year. As a result of the growth in forest acreage (primarily in temperate and boreal regions) through natural forest regrowth and expansion, landscape restoration, and afforestation (defined as the planting of new forests on lands that have not historically contained forests for at least 50 years), the net forest lost is 7.3 million ha/yr worldwide. The IPCC (2007) notes that, although the opportunity for carbon mitigation through afforestation is great, in the short term, reducing deforestation in tropical regions has more impact on carbon mitigation than does new growth through afforestation2.

How will carbon be accounted for in forest products?

How to account for the carbon that is sequestered, stored and released in the life cycle of a forest product (including paper) is an important topic of debate, as a matter of science and also of economics. Carbon is stored in wood fiber and also in the soil. Carbon is emitted when trees are harvested. Should a forest be considered carbon neutral when, as is nearly always the case in North America, a forest that is harvested is replaced with another forest that sequesters carbon? Should the carbon neutrality of a harvested forest be subject to quality of biodiversity in the forest that replaces it? How should the use of forest products that function as a carbon sink, e.g., the dimensional lumber used in construction, be accounted for? How should carbon be tracked across the life cycle of paper from the forest through recovery and re-use?

Adding to the complexity of the issue, different types of forests have different carbon absorption, storage and emissions profiles that depend on climate, geographic region, forest management practices and successional growth rate.

Source: IPCC (2007)

 

1. Barker T., I. Bashmakov, L. Bernstein, J. E. Bogner, P. R. Bosch, R. Dave, O. R. Davidson, B. S. Fisher, S. Gupta, K. Halsn├Žs, G.J. Heij, S. Kahn Ribeiro, S. Kobayashi, M. D. Levine, D. L. Martino, O. Masera, B. Metz, L. A. Meyer, G.-J. Nabuurs, A. Najam, N. Nakicenovic, H. -H. Rogner, J. Roy, J. Sathaye, R. Schock, P. Shukla, R. E. H. Sims, P. Smith, D. A. Tirpak, D. Urge-Vorsatz, D. Zhou, 2007: Technical Summary. In: Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O. R. Davidson, P. R. Bosch, R. Dave, L. A. Meyer (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. (http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ts.html)

2. Nabuurs, G.J., O. Masera, K. Andrasko, P. Benitez-Ponce, R. Boer, M. Dutschke, E. Elsiddig, J. Ford-Robertson, P. Frumhoff, T. Karjalainen, O. Krankina, W.A. Kurz, M. Matsumoto, W. Oyhantcabal, N.H. Ravindranath, M.J. Sanz Sanchez, X. Zhang, 2007: Forestry. In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.(http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch9.html)