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Implications of CO2 fertilization for future climate change in a coupled climate–carbon model.
- Source :
- Global Change Biology; May2007, Vol. 13 Issue 5, p1068-1078, 11p, 4 Charts, 4 Graphs
- Publication Year :
- 2007
-
Abstract
- The terrestrial carbon cycle plays a critical role in determining levels of atmospheric CO<subscript>2</subscript> that result from anthropogenic carbon emissions. Elevated atmospheric CO<subscript>2</subscript> is thought to stimulate terrestrial carbon uptake, through the process of CO<subscript>2</subscript> fertilization of vegetation productivity. This negative carbon cycle feedback results in reduced atmospheric CO<subscript>2</subscript> growth, and has likely accounted for a substantial portion of the historical terrestrial carbon sink. However, the future strength of CO<subscript>2</subscript> fertilization in response to continued carbon emissions and atmospheric CO<subscript>2</subscript> rise is highly uncertain. In this paper, the ramifications of CO<subscript>2</subscript> fertilization in simulations of future climate change are explored, using an intermediate complexity coupled climate–carbon model. It is shown that the absence of future CO<subscript>2</subscript> fertilization results in substantially higher future CO<subscript>2</subscript> levels in the atmosphere, as this removes the dominant contributor to future terrestrial carbon uptake in the model. As a result, climate changes are larger, though the radiative effect of higher CO<subscript>2</subscript> on surface temperatures in the model is offset by about 30% due to reduced positive dynamic vegetation feedbacks; that is, the removal of CO<subscript>2</subscript> fertilization results in less vegetation expansion in the model, which would otherwise constitute an important positive surface albedo-temperature feedback. However, the effect of larger climate changes has other important implications for the carbon cycle – notably to further weaken remaining carbon sinks in the model. As a result, positive climate–carbon cycle feedbacks are larger when CO<subscript>2</subscript> fertilization is absent. This creates an interesting synergism of terrestrial carbon cycle feedbacks, whereby positive (climate–carbon cycle) feedbacks are amplified when a negative (CO<subscript>2</subscript> fertilization) feedback is removed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 13541013
- Volume :
- 13
- Issue :
- 5
- Database :
- Complementary Index
- Journal :
- Global Change Biology
- Publication Type :
- Academic Journal
- Accession number :
- 24826159
- Full Text :
- https://doi.org/10.1111/j.1365-2486.2007.01343.x