The Paris Agreement of December 2015 aims to maintain the global average warming well below 2°C above the preindustrial level. Ecosystem variability during the past 10,000 years was reconstructed from pollen analysis. Only a 1.5°C warming scenario permits Mediterranean land ecosystems to remain within this Holocene variability. At or above 2°C of warming, climatic change will generate land ecosystem changes that are unmatched in the Holocene (2).
In fact, regional temperatures in the Mediterranean basin are now ~1.3°C higher than during 1880-1920, compared with an increase of ~0.85°C worldwide. Climate model projections indicate that the projected warming in the Mediterranean basin this century continues to exceed the global trend. Without ambitious mitigation policies anthropogenic climate change will likely alter ecosystems in the Mediterranean this century in a way that is without precedent during the past 10,000 years. The highly ambitious low-end scenario of climate change (the so-called RCP2.6 scenario) seems to be the only possible pathway toward more limited impacts. Under a high-end scenario of climate change (the RCP8.5 scenario), all of southern Spain turns into desert, deciduous forests invade most of the mountains, and Mediterranean vegetation replaces most of the deciduous forests in a large part of the Mediterranean basin (2).
In addition to climate change, other human impacts affect ecosystems, such as land-use change, urbanization, and soil degradation. Many of these effects are likely to become even stronger in the future because of the expanding human population and economic activity. Without ambitious climate targets, the potential for future managed or unmanaged ecosystems to host biodiversity or deliver services to society is likely to be greatly reduced by climate change and direct local effects (2).
Higher temperatures will favour the growth of thermophilic (tolerant of hot conditions) and xerophilic (tolerant of dry conditions) plant species, and the decline of hydrophilic (tolerant of wet conditions) species. A general shift of flora to a more desert-type assemblage is to be expected. There is still uncertainty on the effects of increased atmospheric CO2 concentrations and global warming, on plant growth and the response of plant metabolic processes. Some recent studies actually suggest that there could be a shift in the opposite direction, with a greening of the Mediterranean and an extension of the Mediterranean woodland further south and east (1).
The most obvious effect of sea level rise is the inundation of low-lying coastal areas. Such areas include all sandy beaches and the gently sloping rocky coasts mostly along the northeastern shoreline. Apart from the actual loss of land area, these locations also support rare and localised habitats containing highly specialised organisms. Inundation will thus result in a landward shift of shore zone patterns and the conversion of littoral to sublittoral habitats. As long as the inundation is a slow process, enough sediment is available and if an ecological corridor is accessible, these threatened habitats may shift inwards. However, constructions built recently along shorelines, which may help to reduce inundation, could inhibit this inward migration. Loss of these habitats will result in reduced biodiversity (1).
An adaptation measure to mitigate inundation of low-lying shores is the designation of building-free zones and construction of protective structures against inundation and coastal erosion. Transplantation of important and/or rare species, and habitat recreation schemes should be considered in vulnerable low-lying coastal areas. Sea grass ecosystems also need to be protected in view of their importance as a special habitat for many marine organisms as well as in combating coastal erosion and in stabilising seabed conditions (1).
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Malta.
- Republic of Malta, Ministry for Rural Affairs and the Environment and the University of Malta (2004)
- Guiot and Cramer (2016)