A preliminary assessment of risk associated to climate and environmental changes in the Mediterranean region by the MedECC network in collaboration with decision-makers
Keywords: climate change, Mediterranean Basin, science-policy interface
Recent accelerated climate change has exacerbated existing environmental problems in the Mediterranean Basin that are caused by the combination of changes in land use, increasing pollution and declining biodiversity. In most impact domains (such as water, ecosystems, food, health and security), current change and future scenarios consistently point to significant and increasing risks during the coming decades. Policies for the sustainable development of Mediterranean countries need to mitigate these risks and consider adaptation options, but currently lack adequate information — particularly for the most vulnerable southern Mediterranean societies, where fewer systematic observations schemes and impact models are based. A dedicated effort to synthesize existing scientific knowledge across disciplines is underway and aims to provide a better understanding of the combined risks posed. This effort has been undertaken by the network of Mediterranean Experts on Climate and Environmental Change (MedECC) supported by the Union for the Mediterranean and Plan Bleu (UN Environment/MAP Regional Activity Center).
This document has been developed by W. Cramer (IMBE, CNRS; MedECC), J. Guiot (CEREGE, CNRS; MedECC) and K. Marini (MedECC). It is to a large extent based on :
Cramer W, Guiot J, Fader M, Garrabou J, Gattuso J-P, Iglesias A, Lange MA, Lionello P, Llasat MC, Paz S, Peñuelas J, Snoussi M, Toreti A, Tsimplis MN, Xoplaki E (2018) Climate change and interconnected risks to sustainable development in the Mediterranean. Nature Climate Change 8, 972-980, doi: 10.1038/s41558-018-0299-2
The report also includes results of discussions among MedECC scientists during workshops and meetings, which have taken place since 2016. It has been prepared in collaboration with Arnault Graves (UfM Secretariat) and Elen Lemaître-Curri (Plan Bleu Regional Activity Centre, UNEP/MAP).
The main results of this preliminary assessment reveal that:
- CLIMATE CHANGE: Average annual air temperatures are now approximately 1.5°C higher than during the preindustrial period, well above current global warming trends (+1.1°C). Without additional mitigation, regional temperature increase will be of 2.2°C in 2040, possibly exceeding 3.8°C in some regions in 2100. Summer precipitation will decrease by 10 to 30% according to the area. Extreme events (heat waves, droughts, floods and fires) become more frequent. Surface seawater temperature has recently increased by about 0.4°C per decade. The projections for 2100 vary between +1.8°C and +3.5°C in average compared to the period between 1961 and 1990. Sea level rises at about 3 mm per yearduring last decades. There are important uncertainties concerning global mean sea level rise in the future. Future projections range goes from 52 to 190 cm global mean sea level increase by 2100. Seawater acidification progresses.
- FOOD SECURITY: Food demand increases and crop, fish and livestock yields decline. Crops quality declines. Phenological cycle becomes shorter (for example grapevines). Regional imbalances in food security and food import dependence increase.
- WATER RESOURCES: Water resources are unevenly distributed around the Mediterranean. Freshwater resources quality and quantity decreases, while the demand for agriculture and tourism increases. This generates use conflicts. Floods and droughts risks increases.
- ECOSYSTEMS :Ecosystems are impacted by climate change, land use change, pollution and overexploitation. Aridity increases and systems become less productive. Fire risk increases. Falling water levels impact wetlands and freshwater ecosystems. Geographic distribution of terrestrial and marine species changes. Number of non-native marine species increases (especially those from the Red Sea). Mass mortality events occur mainly in coralligenousdue to high water temperatures. Sea acidification has a negative impact on carbonate shells and skeletons.
- HUMAN SECURITY: Coastal risks result from rising sea level, storm-surge, flooding, and local land subsidence. Fire risk increases for people living at the forest limit. Social conflicts may be aggravated by droughts. Limited resources and conflicts may lead to large-scale human migrations. Southern and eastern Mediterranean countries are often more vulnerable.
- HUMAN HEALTH:Heat-related illnesses and fatalities become more frequent, especially in the cities (urban heat-island effect). Climate change impacts the emergence of vector- and water-borne diseases. Air, soil and water quality deteriorate. Pollen allergies expand. Sanitary conditions may deteriorate because of societal and political situation.