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Aerosol indirect effect on biogeochemical cycles and climate
1Department of Earth and Atmospheric Sciences, Atkinson Center for the Sustainable Future, Cornell University, Ithaca, NY 14850, USA.
Science (New York, N.Y.)
|November 15, 2011
Summary
Anthropogenic aerosols impact climate through direct and indirect effects. A newly identified indirect effect via biogeochemical feedbacks, driven by CO(2) changes, has a significant cooling impact, potentially increasing climate mitigation costs.
Area of Science:
- Climate Science
- Atmospheric Chemistry
- Biogeochemistry
Background:
- The climate impact of anthropogenic aerosols is typically assessed by direct radiative and indirect aerosol-cloud interaction effects.
- A longer-term aerosol impact through biogeochemical feedbacks, primarily altering atmospheric CO(2) concentrations, has been less explored.
Purpose of the Study:
- To quantify the net biogeochemical effect of anthropogenic aerosols on climate.
- To assess the implications of this effect for climate mitigation strategies and carbon targets.
Main Methods:
- Analysis of aerosol impacts on land and ocean biogeochemical cycles.
- Estimation of the radiative forcing equivalent of the net biogeochemical effect.
Main Results:
- Aerosols influence biogeochemical cycles through physical forcing, nutrient addition, and pollutant effects.
- The net biogeochemical effect of aerosols is estimated to cause a radiative forcing of -0.5 ± 0.4 watts per square meter.
Conclusions:
- The indirect climate effect of aerosols via biogeochemical feedbacks is substantial.
- Achieving lower carbon targets may be more economically challenging than previously projected due to these aerosol effects.
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