Atmospheric Composition, Biogeochemical Cycles, and Climate Change
This workshop explored topics associated with changes in atmospheric composition. The two main areas of focus were: climate driven changes in biogeochemical cycles (such as increased release of methane from wetlands) and climate change impacts on regional air quality.
Keywords: carbon cycle; atmospheric composition; nitrogen cycle, biogeochemical cycles
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.
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1:00 pm Working Group Meetings
Although carbon dioxide (CO2) has received the majority of attention related to global warming, methane (CH4) is also a powerful greenhouse gas and its impact on global warming over the last century is equal to about forty percent of the impact of carbon dioxide. In this lecture, Dr. Elaine Matthews, research scientist at NASA’s Goddard Institute for Space Science, reveals that seventy percent of global methane emissions each year results from human activities such as rice irrigation, livestock raising, biomass burning, mining and processing of coal, and production and transmission of natural gas and oil. Matthews discusses methane’s short lifetime and the implications of the reduction of its sources, which would make a significant impact on the course of global warming.