The Mediterranean Basin: a region affected by accelerating environmental change

A network of scientists has undertaken the first synthesis of multiple changes in the environment that impact the livelihoods of people in the entire Mediterranean Basin. 

In this region, average temperatures have already risen by 1.4°C since the pre-industrial era, 0.4°C more than the global average. During the last two decades, sea level has risen by 6 cm and sea water acidity has significantly increased. Even if future global warming is limited to 2°C, as prescribed by the Paris Agreement, summer rainfall is at risk to be reduced by 10 to 30 percent in some regions, thereby enhancing existing water shortages and causing loss in agricultural productivity, particularly in southern countries. To satisfy agricultural water needs, irrigation would instead have to be increased by 4 to 22 percent to compensate for the growing human population. This demand will be in conflict with other uses, such as drinking water, tourism, and industry. Combined with the ongoing switch to more animal-based food production, Southern countries in the Mediterranean Basin are at risk to increase their dependence on trade. Also for fisheries, risks are due to a combination of forcings, besides climate change and acidification, overfishing being a key problem. 

Global loss of ice volume in Antarctica, Greenland and many mountain areas causes accelerated sea level rise, higher than recent estimates. This rise directly affects the Mediterranean where a large part of the population lives very close to the coast and would be affected by storm surges. Intrusion of saltwater impacts agricultural soils in many areas, such as the Nile Delta. Public health is impacted by multiple trends of change, through heat waves and pollution (cardiovascular or respiratory diseases), and also through disease vectors (West Nile virus, Dengue, Chikungunya) increasing their distribution. Particularly in unstable countries, risks associated with socio-economic problems and their consequences (such as war, famine and migration) are more and more due to these changes in the environment.

To facilitate decision-making in the face of these risks, a scientific synthesis of current knowledge is needed, covering all relevant disciplines, sectors and subregions. The recent assessment reports of the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES) provide useful knowledge but they have not permitted an integrated view on the Mediterranean Basin. Therefore, the MedECC (Mediterranean Experts on Climate and Environmental Change) network has been established, currently involving 400 scientific experts, supported by government agencies and other partners. The goal of MedECC is to produce a full synthesis of risks and present it to decision makers for debate and approval.

Wolfgang Cramer, Co-Chair of the Scientific Steering Committee of the Future Earth Global Research Project ecoSERVICES, is the lead author of this new review article in Nature Climate Change. We spoke with him to further understand the risks presented in this publication and what is currently being done to address them.

Wolfgang Cramer: Like many parts of the world, the Mediterranean Basin suffers from a combination of different aspects of environmental change (warming, drying, acidification, pollution, invasive species etc.) and also a growing demand of services provided by its ecosystems. While a lot is known about this in parts of the basin, no synthesis exists of the current status nor of risks to be expected in the future. What’s worse, Southern and Eastern Mediterranean countries have less monitoring and risk analysis capacity, potentially larger risks and much more limited financial resources for adaptation.

FE: When it comes to water in the Mediterranean Basin, now and in the future, there are threats of sea level rise, saltwater intrusion, and water scarcity on land for consumption and agriculture. In an area known identified by its close ties to the sea, what are the growing risks for its populations on land when it comes to water? What information or data is needed to help mitigate these risks?

WC: The Mediterranean is unique in the world with regard to the high level of agreement across climate models for the expected reduction in rainfall. Combined with warming and increasing freshwater use, it is clear that shortages will become more severe, and these shortages will harm many sectors such as agriculture and tourism. To this comes sea level rise, probably underestimated by earlier assessments (given the alarming observations from Greenland and Antarctica), which affects arable soils, notably in intensively used river deltas such as those of the Nile, the Po and elsewhere. Finally, due to the absence of tides, coastal infrastructures in the Mediterranean are closer to current mean sea levels than is the case, for example, in Northern Europe – this causes significant vulnerabilities too.

FE: Human health and security are included as two of the five categories discussed in this publication. What are the biggest upcoming risks for human populations in the Mediterranean Basin and what information or data is essential to managing and preparing for them?

WC: For health, there is growing evidence that climate change enhances the risk of infectious diseases, especially through new opportunities for their vectors to thrive: West Nile Virus is one of them. Past heat waves have also caused loss of life more directly, through dehydration or food poisoning, especially of poor people. Security, however, is more than just health. While nobody currently claims that wars have been caused by environmental change, a number of studies have shown that the weakening of the social fabric associated with losses in agricultural production have contributed to conflict and migration in Syria. Future environmental change will very likely exacerbate these trends.

FE: You are a co-founder of the Mediterranean Experts on Environmental and Climate Change (MedECC), which is an international network of more than 400 scientists. How is MedECC identifying knowledge gaps and seeking a comprehensive and coherent risk assessment for climate change in the Mediterranean Basin?

WC: MedECC currently works on its first assessment report which will be completed early 2020. In all modesty, we model our activities along the example of IPCC and IPBES. This implies that we have invited for very broad and voluntary participation by scientists from all countries and disciplines. We have carried out a selection procedure for the leading roles, aiming to assure good geographic and thematic coverage as well as good gender balance. We have also undertaken a scoping process with many participants, resulting in a comprehensive outline which is now being filled with results from the scientific literature. Supported by the Union for the Mediterranean, we operate a small coordinating office, hosted by Plan Bleu in Marseille. Our paper in Nature Climate Change represents the scientific starting point of this operation.

Climate change and interconnected risks to sustainable development in the Mediterranean.
Nature Climate Change online, doi : 10.1038/s41558-018-0299-2

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 

Contacts:

Wolfgang Cramer, Mediterranean Institute for Biodiversity and Ecology (IMBE), CNRS, Aix-Marseille Université, IRD, Université d’Avignon, Aix-en-Provence, e-mail wolfgang.cramer@imbe.fr,
https://www.imbe.fr/wolfgang-cramer, tel. +33-6-82-04-35-95

Joël Guiot, Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE), CNRS, Aix-Marseille Université, IRD, INRA, Collège de France, Aix-en-Provence, e-mail guiot@cerege.fr,  http://www.otmed.fr/people/guiot-joel, tel. +33-6-22-91-18-44