The sensitivity of ecosystems to global change
Keywords: changes, climate, biodiversity, species, threat, studies
A study carried out by several European laboratories, including the Alpine Ecology Laboratory (CNRS - Université Grenoble 1 - Université Chambery), shows that the sensitivity of ecosystems to global changes could increase the vulnerability of certain European regions by the end of the 21st century. century. This vulnerability would be the result of a decline in biodiversity, soil fertility or water resources. This phenomenon would affect more particularly the Mediterranean and mountain regions. This work was published in Science Online on October 27, 2005.
Depending on the region, this reduction in ecological services may or may not be counterbalanced by the benefits of the increase in the productivity of bioenergy crops and forests, of the forest area or of the areas released by agriculture for recreation or conservation of the forest. biodiversity. These predictions are based on modeling the response of ecological services to scenarios of climate change, atmospheric carbon dioxide content, and land use, derived from the scenarios of the Intergovernmental Panel on Climate Change (GICC).
The results of this modeling represent possible futures based on hypotheses on the orientations of global society and their consequences in terms of energy policies. It is unique in Europe by the number of scenarios and models considered, and the diversity of ecological services analyzed in consultation with the socio-economic sectors concerned.
The climate scenarios considered show strong inter-regional variations but, without exception, contribute to a warming of 2,1 to 4,4 ° C on average over Europe, particularly marked in the northern regions. The projections of changes in precipitation are highly uncertain, but all the scenarios considered lead to a decrease in rainfall in the south, especially in summer, while it would increase in the north.
The most important predictive facts are:
- The opportunities to adapt energy production towards more sustainable strategies through bioenergy crops would be strong for the regions of northern Europe, but limited in the south due to drought.
- Likewise, forest production would increase overall in Europe, and in particular in the north, under the combined effect of the increase in productivity due to climate and CO2, and the available surfaces. Despite this potential increase, silvicultural management decisions would continue to regulate production under the influence of markets and public policies. For the Mediterranean regions there would be added risks linked to the sharp increase in fires.
- The projected increase in population and climate change would reduce the availability of water for many already deficient regions, especially in the Mediterranean region. These effects would be further accentuated by increasing demands for irrigation and tourism. In addition, the changes in hydrological regimes in mountain regions resulting from the decrease in precipitation in snowy form would lead to reduced availability during summer periods (e.g. for irrigation and hydroelectric production), while the risks major winter floods would increase.
- The decrease in snow cover would also affect tourism in mountain regions, accentuating a situation already observed today.
- The effects on biodiversity would be particularly acute, with local losses that can exceed 50% of plant species currently present in the most sensitive regions such as mountain ranges and the Mediterranean region. Depending on the intrinsic capacities of species to migrate as they did after glaciations, and the barriers represented by changes in landscapes by human activities (e.g. agriculture, urbanization), these species losses may or may not be compensated for. by the arrival of new species, for example in temperate or boreal regions. Anyway, many regions would see their flora, and therefore their landscapes radically changed.
- The combination of the increase in primary productivity, in particular in forestry, and the reduction in agricultural land would initially make it possible to increase the current carbon sink. This trend would be reversed from 2050 by the effects of the increase in temperature.
- The more 'economic' oriented scenarios tend to produce the most severe effects for all the services examined. However, even for the most proactive scenarios in terms of the environment, and therefore the least severe in terms of climate change, the impacts on certain services such as biodiversity, water availability or organic soil fertility remain significant. .
In this collaborative research, the team of Sandra Lavorel from the Laboratory of Alpine Ecology in Grenoble, brought its skills to the field of work carried out on biodiversity. She also participated in the modeling of land use scenarios.
Ecosystem Service Supply and Vulnerability to Global Change in Europe. Schröter, D., Cramer, W., Leemans, R., Prentice, IC, Araújo, MB, Arnell, NW, Bondeau, A., Bugmann, H., Carter, TR, Garcia, CA, de la Vega-Leinert , AC, Erhard, M., Ewert, F., Glendining, M., House, JI, Kankaanpää, S., Klein, RJT, Lavorel, S., Lindner, M., Metzger, MJ, Meyer, J., Mitchell, TD, Reginster, I., Rounsevell, M., Sabaté, S., Sitch, S., Smith, B., Smith, J., Smith, P., Sykes, MT, Thonicke, K., Thuiller, W., Tuck, G., Zaehle, S., & Zierl, B. (2005). Science Online, October 27, 2005.
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