Keynote Presentations from the 2nd AVEC International Summer School, Peyresq, 18-30 September 2005

Speaker: Marc Metzger
Wageningen University Department of Plant Sciences, PO Box 432, 6702 AK Wageningen, The Netherlands

Title of the talk: European vulnerability to global change (pdf: 8MB)

Summary of the talk by Andrej Baca: Students´ summary


European vulnerability to global change

Terrestrial ecosystems provide a number of vital services for people and society. These services include among others: biodiversity, food and fiber, water resources, carbon sequestration and recreation. The future capability of ecosystems to provide these services is determined by changes in socio-economic characteristics, land use, biodiversity, atmospheric composition and climate. Collectively, these changes are referred to as “global environmental change”. The numerous interactions between ecosystems, competing land uses and global change call for a highly quantitative integrated assessment of ecosystem responses and the consequent changes in ecosystem services.

Most published impact assessments do not address the vulnerability of ecosystems and ecosystem services under such environmental change. These assessments can be viewed as comprehensive sensitivity studies of specific ecosystems or sectors, which depend on the continuation of a particular ecosystem service. Nevertheless they cannot answer important multidisciplinary questions such as:

Within the EU project ATEAM ( a full suit of ecosystem models, covering biodiversity, agriculture, forestry, hydrology and carbon sequestration are fed with the same input data and are run with the same consistent SRES-based scenarios. Each model will give insights into specific ecosystems as in traditional impact assessments. Moreover, by integrating the results in a Vulnerability Assessment, multidisciplinary questions, such as those listed above, can be answered as well. Society is vulnerable (literally ‘the state of being open to harm or damage’) when an ecosystem service in want is no longer available and society does not have a suitable alternative. By quantifying the undesired state of being vulnerable for the different ecosystem services, the impacts of global change on totally different ecosystems can be compared.

In the IPCC Third Assessment Report presents a framework of definitions around the term vulnerability. Within ATEAM these definitions are maintained where possible. Within ATEAM vulnerability is defined as ‘the degree to which an ecosystem service is sensitive to global change plus the degree to which the sector that relies on this service is unable to adapt to the changes’. Form this definition it is clear that a measure of vulnerability is dependant on three things: (1) the exposure of a location to global change, (2) the way the ecosystem services are affected by this change (sensitivity) and (3) the way in which humans are able to adapt to ecosystem changes (adaptive capacity). Exposure is quantified by the global change scenarios that feed in to the ecosystem models. The models formalize the sensitivity of the ecosystem processes, i.e. the rules in the model express how ecosystem services respond to a given exposure. The model outputs are therefore an expression of the system’s sensitivity to a given exposure. Adaptive capacity is very difficult to quantify. In socio-economic literature it is recognized that adaptive capacity is determined, among others, by society’s economic power, freedom, motivation, flexibility and knowledge. Indicators for these determinants of adaptive capacity are being used to determine a generic indicator of adaptive capacity for different regions.

One essential requirement for making comparisons across Europe is that the heterogeneous European environment is stratified into relatively homogeneous regions, since statistical inference requires data to be representative of a defined population. Within a stratum, changes of effects can be analyzed separately from environmental heterogeneity in the classical statistical procedure of partitioning the sums of squares between classes. For example, when comparing the influence of global change on species abundance within an environmental class, one can be sure that differences in species abundance are indeed caused by that change, and not by inherently different environments. ATEAM’s Vulnerability Assessment makes use of a statistical stratification that will facilitate the calculation of Vulnerability values, which can then be compared across Europe.

Over the last two years a framework has been developed which will combine exposure, sensitivity and adaptive capacity measures into standardized values that will express the vulnerability of humans to changes in ecosystem services under global change. Awaiting the definitive outputs of the ATEAM ecosystem models, which unfortunately have been delayed by some months, it will now be a valuable exercise to analyze the behavior of the proposed framework. Using some dummy vulnerability maps, we will together attempt to analyze and compare different situations and test the proposed approach to vulnerability mapping.

Recommended background literature on this presentation:

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