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Atmospheric Composition, Biogeochemical Cycles, and Climate Change

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Session Description: 

Several major question marks in evaluating future changes in climate and its impacts on society and the environment relate to changes in atmospheric composition. In particular, this session focused on two primary areas of concern:
1. Feedbacks on biogeochemical cycles, and
2. Impacts on air quality.

Projections of greenhouse gas emissions and concentrations tend to give little consideration to potential feedbacks of climate change on the biogeochemical cycles driving the natural emissions of these gases. The question is: Could feedbacks on biogeochemical cycles from climate change result in a significantly different picture of the future climate than current projections? Could resulting changes in atmospheric composition lead to further enhancements in the changing climate? The recent unexpected increase in the trend of methane may be an example of the sources (e.g. wetlands) of methane responding to the changing climate.

Changes in climate could lead to increased concern about local to regional air quality, which in turn could have effects at the global scale. To what extent could climate change have a major impact on air quality? What local to regional effects on ecosystems, etc. could result from the changes in air quality? Could the changes in emissions and composition affecting air quality at the local to regional scale lead to changes in composition at the global scale that could further affect climate?

Feedbacks on biogeochemical cycles
This aspect of the session examined the current understanding and research needs associated with potential climate feedbacks and greenhouse gases like CO2, CH4, and N2O, plus considered potential feedbacks on aerosol precursors. The session also considered potential ecological impacts from the changes in biogeochemical cycles. Finally, the session attempted to put some bounds on the potential effects of these feedbacks on projecting the future climate.

Impacts on Air Quality
This part of the session examined the current understanding and research needs associated with climate impacts on air quality and its regional effects, and attempted to put some bounds on the changes in air quality on local to regional to global scales.

Workshop Topic (s): 
  • Atmospheric Composition
  • Carbon Cycle
  • Climate Variability and Change (including Climate Modeling)
  • Ecosystems
  • Water Cycle