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Biodiversity in a Changing Climate: Assessing Uncertainties

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Session Description: 

In May of 2004, in preparation for the Fourth Assessment, IPCC held a workshop on "Describing Scientific Uncertainties in Climate Change to Support Analysis of Risk and of Options" in Maynooth, Ireland. Major gains could be seen in many of the fields. In particular, Parmesan made the argument that it is now "well established" (sensu Moss and Schneider, 2000), that climate change was a major causal factor driving responses of wild species globally (assessed in Parmesan and Galbraith 2004, Parmesan and Yohe 2003, and Root et al. 2003). Ironically, perhaps the weakest field at the workshop was also within biology - that of ecological projections of future climate change impacts. The U.S. and global conservation communities, which have been slow to accept climate change as a major conservation issue, are now attempting to incorporate climate change into their planning agendas, but finding little theoretical support for the planning process.
IUCN- The World Conservation Union is an umbrella conservation organization with several hundred members made up of governments and conservation NGOs. The IUCN has just formalized a Climate Change Task Force of the Species Survival Commission, with Camille Parmesan as Chair. A major goal of this task force is to develop guidelines for mitigating biodiversity loss with future climate change. Two workshops have been held towards this end. These workshops were comprised principally of bioclimate modelers and field biologists specializing in observed impacts. Bioclimate modelers use correlations between species' current distributions and environmental variables (including climate) to model responses to change in the geography of a species climate envelope with climate change. In general, bioclimate modelers do not incorporate the uncertainties and pitfalls associated with real climate data as well as with climate projections. Further, this field is only just beginning to understand how different driving forces affect the outputs of different models, and under what conditions a particular model might work best.
One product of these workshops was a paper in Nature which estimated numbers of species at risk of extinction under different climate scenarios (Thomas et al. 2004). While useful as a warning bell, that paper also exposed serious problems with the current state of ecological models and their outputs. There was large variation in projected extinctions across different studies, with little understanding whether those differences stemmed from inherent differences in model assumptions and drivers, or real differences among taxonomic groups and geographic regions. Understanding the sources of variation among impact projections is important in assessing how (or if) these should be used in biodiversity and conservation planning.
Studies of potential biodiversity impacts of climate change would benefit from a broader approach which synthesises information and methodologies from other disciplines. Better incorportation of uncertainties from climate data and projections into biological models will aid interpretation. As importantly, methodologies from decision making theory could be adapted to help assess different conservation strategies in the face of multiple possible biodiversity scenarios (in the style of Yohe et al. 2004 for carbon mitigation).
The Aspen Global Change Institute has a strong history of bringing together disparate disciplines to work on common questions. This workshop builds on the partnerships forged during a 1998 AGCI workshop which brought together climate scientists and biologists under the banner: "Climate Extremes: Changes, Impacts and Projections". The broad goal of this workshop is to better define and interpret uncertainties in projections of climate change impacts on biodiversity.
Ultimately, incorporating uncertainties the planning process could lead to more informed decisions within the policy community, and for better management of biodiversity under climate change.

There are three related goals of this workshop:

Objective #1: to provide a qualitative, if not quantitative, assessment of current uncertainties in biodiversity impact projections. Anticipated product is a scientific paper at a level appropriate for use in the IPCC Fourth Assessment

Objective #2: Using the above uncertainty assessment, provide guidelines for conservation planners as to the most appropriate use of projections of biodiversity impacts from different sources. Anticipated product is an IUCN distributed report.

Objective #3: Provide guidelines for adopting existing methodologies or new research that would aid in reducing uncertainties in impact projections.

Workshop Topic (s): 
  • Carbon Cycle
  • Climate Variability and Change (including Climate Modeling)
  • Ecosystems
  • Land-Use/Land-Cover Change