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 change could increase the vulnerability of certain European regions by the end of the 21st 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 offset by the benefits of increasing the productivity of bioenergy crops and forests, the forest area or the areas freed up by agriculture for recreation or conservation. biodiversity. These predictions are based on the modeling of the response of ecological services to climate change scenarios, 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 assumptions about the directions of global society and their consequences in terms of energy policies. It is unique in Europe by the number of scenarios and models envisaged, and the diversity of ecological services analyzed in consultation with the socio-economic sectors concerned.
The climatic scenarios envisaged show strong inter-regional variations but contribute, without exception, to a warming of 2,1 to 4,4 ° C on average over Europe, particularly marked in the northern regions. Projections of changes in precipitation are highly uncertain, but all the scenarios envisaged lead to a decrease in rainfall in the south, particularly in summer, while it would increase in the north.
The most important predictive facts are:
- The opportunities to adapt energy production to more sustainable strategies through bioenergy crops would be strong for the regions of northern Europe, but limited in the south due to drought.
- In the same way, forest production would increase overall in Europe, and in particular in the north, under the combined effect of the increase in productivity by climate and CO2, and the available areas. Despite this potential increase, silvicultural management decisions would continue to regulate production under the effect of markets and public policies. For the Mediterranean regions, there are the risks linked to the sharp increase in fires.
- The projected population increase and climate change would reduce the availability of water for many already deficient regions, particularly in the Mediterranean region. These effects would be further accentuated by increasing demands for irrigation and tourism. In addition, changes in hydrological regimes in mountain regions resulting from the decrease in snowfall precipitation would lead to reduced availability during summer periods (eg 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 may exceed 50% of the plant species currently present in the most sensitive regions such as the mountain ranges and the Mediterranean region. Depending on the intrinsic capacities of species to migrate as they did after the glaciations, and the barriers represented by the modification of landscapes by human activities (eg agriculture, urbanization), these losses of species may or may not be compensated 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 an increase in primary productivity, in particular in forestry, and a decrease in agricultural areas would initially allow the current carbon sink to be increased. This trend would be reversed from 2050 due to the effects of the temperature increase.
- The scenarios with a more 'economic' orientation tend to produce the most severe effects for all the services examined. However, even for the most pro-active environmental scenarios, 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 Alpine Ecology Laboratory in Grenoble, brought their skills in 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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