Document type
Book chapters
Title
Climate and Environmental Change in the Mediterranean Basin – Current Situation and Risks for the Future. First Mediterranean Assessment Report
Participants in the publication
Balzan MV (Author)
Hassoun AER (Author)
Aroua N, (Author)
Baldy V, (Author)
Bou Dagher M, (Author)
Cristina Branquinho (Author)
Dep. Biologia Vegetal
Dep. Biologia Vegetal
cE3c
Dutay J-C (Author)
El Bour M, (Author)
Médail F (Author)
Summary
Executive summaryMarine ecosystemsDespite covering only 0.82% of the ocean’s surface, the Mediterranean Sea supports up to 18%of all known marine species, with 21% being listed as vulnerable and 11% as endangered. Theaccelerated spread of tropical non-indigenous species is leading to the “tropicalization” ofMediterranean fauna and flora as a result of warming and extreme heat waves since the 1990s.The acidification rate in the Mediterranean waters has ranged between 0.055 and 0.156 pHunits since the pre-industrial period, affecting the marine trophic chain, from its primary pro-ducers (i.e., coccolithophores and foraminifera) to corals and coralline red algae.Projections for high emission scenarios show that endemic assemblages will be modified withnumerous species becoming extinct in the mid 21st century and changes to the natural habitatsof commercially valuable species, which would have many repercussions on marine ecosystemservices such as tourism, fisheries, climate regulation, and ultimately on human health.Adaptation strategies to reduce environmental change impacts need effective mitigation pol-icies and actions. They require anticipatory planning to enable them to tackle problems whilethey are still manageable. Given the diversity of each Mediterranean sub-basin, wider moni-toring coverage is needed to strengthen our knowledge about the different adaptation pro-cesses that characterize and best suit each geographical zone. Adaptation implies the imple-mentation of more sustainable fishing practices as well as reducing pollution from agriculturalactivity, sustainable tourism or developing more effective waste management. Marine pro-tected areas can potentially have an insurance role if they are established in locations not par-ticularly vulnerable to ocean acidification and climate change.Coastal ecosystemsThe coastal zone, i.e. the area in which the interaction between marine systems and the landdominate ecological and resource systems, is a hotspot of risks, especially in the south-easternMediterranean region. Alterations to coastal ecosystems (lagoons, deltas, salt marshes, etc.)due to climate change and human activities affect the flow of nutrients to the sea, the magni-tude, timing and composition of potentially harmful/toxic plankton blooms. They also signifi-cantly increase the number and frequency of jellyfish outbreaks, and could have negative im-pacts on fisheries. 1.2 to 5% of seagrass meadows in the Mediterranean Sea, which represent5 to 17% of the worldwide seagrass habitat, are lost each year. Among them, almost half ofthe surveyed Posidonia oceanica sites have suffered net density losses of over 20% in 10 years.As for fish, non-indigenous species and climate change cause local extinction.Projected temperature increases combined with a decrease in nutrient replenishment andocean acidification, are expected to cause changes in plankton communities, negative impactson fish, corals, seagrass meadows and propagation of non-indigenous species. Projected sealevel rise will impact coastal wetlands deltas and lagoons. Extensive urbanization added to cli-mate change is also expected to threaten coastal ecosystems, human health and well-being.A nexus approach is required when trying to establish adaptation methods for the entire Med-iterranean, while taking into account ecosystem-based management, synergies and conflicts,integrating local knowledge and institutions. Suitable adaptation policies include reducing pol-lution runoff, both from agriculture and industry and waste management, and policies to limitor prevent acidification. Conservation planning and management should focus on cross-cuttingapproaches and building resilience between structural and functional connectivities of variousfields.\\\\nPage 6\\\\n6Terrestrial ecosystemsBiodiversity changes in the Mediterranean over the past 40 years have occurred more quicklyand been more significant than in other regions of the world. Urbanization and the loss ofgrasslands are key factors of ecosystem degradation across the region. Since 1990, agriculturalabandonment has led to a general increase in forest areas in the northern Mediterranean,while in the southern Mediterranean, ecosystems are still at risk of fragmentation or disap-pearance due to human pressure from clearing and cultivation, overexploitation of firewoodand overgrazing. Drylands have significant biodiversity value, with many of the plants and an-imals highly adapted to water-limited conditions. They are undergoing an overall increase inresponse to climate change and extensive land abandonment. 48% of Mediterranean wetlandswere lost between 1970 and 2013, with 36% of wetland-dependent animals in the Mediterra-nean threatened with extinction. Because of the reduction in river flows, 40% of fish speciesin Mediterranean rivers are endangered.Projections for the 21st century indicate drier climate and increased human pressure, with neg-ative impacts on terrestrial biodiversity, forest productivity, burned areas, freshwater ecosys-tems and agrosystems. Future projections indicate that burnt areas can increase across theregion by up to 40% in a 1.5°C warming scenario and up to 100% from current levels for 3°Cwarming at the end of the century. Mediterranean drylands will become drier and their extentis expected to increase across the region. Projections suggest decreased hydrological connec-tivity, increased concentration of pollutants during droughts, changes in biological communi-ties as a result of harsher environmental conditions, and a decrease in biological processessuch as nutrient uptake, primary production, and decomposition.Promotion of ‘climate-wise connectivity’ through permeability of the landscape matrix, disper-sal corridors and habitat networks are key to facilitating upward the migration of lowland spe-cies to mountains in order to adapt to new climate change conditions. Promotion of mixed-species forest stands and sylvicultural practices such as thinning, and management of under-story can promote the adaption of Mediterranean forests to climate change. Promotion of thespatial heterogeneity of the landscape matrix can help reduce fire impacts. The preservationof the natural flow variability of Mediterranean rivers and streams and wide riparian areas,along with reductions in water demand are key to the adaptation of freshwater ecosystems tofuture climate change
Editor(s)
Cramer, W., Guiot, J., Marini, K. (eds.)
Institution
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DE LISBOA
Where published
Union for the Mediterranean, Plan Bleu, UNEP/MAP, Marseille
Publication Identifiers
ISBN - ISBN: 9782957741601
Address
Marseille, France
Document Identifiers
DOI -
https://doi.org/10.5281/zenodo.4768833
Awards
North South Prize