The 2013 US National Climate Assessment: Impacts of Climate Change on Ecosystems and Biogeochemical Cycles, and Opportunities for Adaptation and Mitigation [INVITED]

This paper will report the draft findings of the 2013 National Climate Assessment chapters on “Ecosystems, Biodiversity, and Ecosystem Services” and “Biogeochemical Cycles.” The impacts of climate change can be difficult to assess against a background of other globally prevalent and mainly anthropogenic changes, including alterations in biogeochemical cycles, which interact with climate change. Each chapter drew on technical input received from hundreds of scientists from diverse sectors (academia, non-governmental organizations, business, and government), reflecting the most current research findings in each area. Emphasis in the evaluation of biodiversity changes was on how rapidly distribution and phenology are shifting in space, how composition of species assemblages and their interactions are changing, and individualistic species responses. For impacts on ecosystems, the focus was on the fluxes of matter (carbon, nitrogen, and other materials) and energy and the biotic and abiotic elements of structure that contribute most to those fluxes. Consideration of ecosystem services, the benefits that people derive from ecosystems, was new for this assessment. Also developed for the first time, the focus in the biogeochemical cycles chapter was both on the factors driving changes in radiative forcing from greenhouse gases other than CO2, as well as the potential enhanced carbon sequestration from biogeochemical changes. The ways in which our knowledge of the interactions of multiple anthropogenic changes may be useful in adaptation planning and mitigation strategies will be discussed.