Vulnerabilities - Terrestrial biodiversity

Spring advancement flowering trees

The response of budburst, leaf unfolding, flowering, fruit ripening, fruit harvesting, leaf colour change and leaf-fall to climate change was studied for the period 1986 - 2012 for 17 sampling sites in Spain. In 61% of these sites early spring phenophases advanced, especially budburst on average by -0.67 days and flowering on average by -0.15 days during the studied period, and also in the subsequent fruit ripening and harvesting phases on average by -1.06 days. By contrast, 63% of the sampling sites showed a delay in autumn vegetative phases, especially leaf-fall events on average by +1.15 days (37).

Mediterranean

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 (36).

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 (36).

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 (36). 

Spain

Spain is possibly the EU country with the most rich animal species diversity (3). Up to 97% of animal species may be affected by climate change. Most vulnerable ecosystems are the islands and isolated ecosystems in the mountains (4). A simplification of vegetation structure is already taken place in Spain, and there is more local extinction of plants than recolonization (3).

The drying of peatland has particular implications for climate change, since the aeration and oxidation that occurs lead to a loss of accumulated organic matter and change peat soils from sinks into sources of carbon. In the Guadiana catchment in Spain, the drying out of peatland through excessive groundwater abstraction and rainfall scarcity has at times already resulted in its spontaneous combustion and almost all of the peat is now burnt (5).

Vulnerabilities - Fresh water biodiversity

The Mediterranean ecohydrology is vulnerable to climate change, and can affect flora and fauna of the region. In arid and semi-arid parts of the region, the biggest danger facing the lakes is the expected decrease in water input resulting from increasing evapotranspiration with increasing temperature and decreasing precipitation. This process can lead to conversion of existing freshwater to saltwater (7).

Higher temperatures of river water may also affect biodiversity. A simulation of water temperature in the North of Spain for the period 1990-2100 under an intermediate scenario of climate change (the so-called SRES A1B scenario) shows an increasing trend, which is higher for the period of June-August (summer) and September-November (autumn) (0.0275 and 0.0281°C/year) than that of winter (December-February) and spring (March-May) (0.0181 and 0.0218°C/year). Daily water temperature may increase up to 2.2-3.1°C for 2061 - 2090 relative to 1961 - 1990 (38).

Doñana wetlands

The Doñana wetlands in southern Spain provide the most important wintering site for waterfowl in Europe. They contain the largest temporary pond complex in Europe, with a diversity of amphibians and invertebrates. Its marshes are threatened by eutrophication due to pollution and reduced flow of incoming streams, promoting toxic cyanobacterial blooms, and dominance by invasive floating plants that create anoxic conditions in the water (33). In addition, groundwater extraction has major effects (34). Due to these local stressors, Doñana is vulnerable to climate change. UNESCO has just rated this World Heritage Site as under “very high threat” (33).

Vulnerabilities - Marine biodiversity

Bay of Biscay

Global models forecast a long-term decrease of primary production in the North Atlantic (15). In regional waters such as the Bay of Biscay, however, developments may be different since nutrient concentrations in these waters heavily depend upon river discharges (16).

From bottom survey time series an increase of the abundance of fish species with a wide latitudinal distribution (mainly subtropical) was found in the Bay of Biscay, whereas the abundance of temperate and least widely distributed species had decreased (11). In a study focusing on flatfish further north along the Atlantic coast a decrease in northern spawners such as plaice and dab, and an increase of southern spawners was found (12).

The projected increase in sea temperature over the Bay of Biscay, a weakening in the Atlantic thermohaline circulation and an increase in stratification will change the geographical distribution of species (13). These changes will result in: (1) shifts of fish populations, with the invasion of alien species and disappearance of native species; and (2) direct influence on survivorship, reproduction, dispersal, fertility and the behaviour of individuals and, thus, on abundance and distribution, as also stated for other marine areas (14).

Decline in kelp populations attributed to ocean warming has occurred off the north coast of Spain (32).

Mediterranean Sea

Several distinctive features make the Mediterranean Sea particularly sensitive to climate change:

• The hot dry summers and scarcity of river inputs make the Mediterranean Sea a concentration basin;
• Due to the small size of the Mediterranean Sea the impact and rate of climate change will be large and rapid. The average water depth is around 1500 m, and the renewal rate of deep water is relatively fast, between 15 and 50 yr (18). Heat and CO2 penetration is therefore very rapid (19), and the effects of these changes on marine organisms may become apparent rather quickly;
• The Mediterranean Sea is oligotrophic, i.e. it has very little macronutrients (nitrate, phosphate, silicate) in the surface waters. This is because the Mediterranean Sea receives Atlantic surface waters (poor in nutrients) through the Strait of Gibraltar, while it exports, through this strait, deep Mediterranean water rich in remineralized nutrients. This makes the Mediterranean Sea a nutrient-poor system with limited productivity;
• The Mediterranean Sea contains high biological diversity. Although it occupies only 0.82% of the global ocean surface, it contains 6.3% of all described marine macrophyte and metazoan species (20).

The Mediterranean Sea shows a gradual salinisation of the water, especially in the intermediate and deep layers (more than 150 m deep) (28), that seems to be related to the general decrease in rainfall and increase in evaporation in the Mediterranean area, and to the decrease in river flow to the sea due to the construction of dams and reservoirs (29). From a number of model experiments and three climate change scenarios (B1, A2 and A1B, respectively optimistic, pessimistic and intermediate scenarios in terms of gases emissions) it was concluded that the mean Mediterranean sea surface temperature will increase with a range between +1.73 and +2.97 °C in 2070–2099 compared to 1961–1990. These experiments project mean Mediterranean sea surface salinity increase with a range between +0.48 and +0.89 for the period 2070–2099 compared to 1961–1990 (35). 

The Mediterranean Sea has certain characteristics that make it especially sensitive and vulnerable to changes in atmospheric CO2 and gradual acidification. Due to the short residence time of the Mediterranean deep waters (15 to 50 years), the penetration of anthropogenic CO2 is much faster in the Mediterranean Sea than in the Earth’s oceans, resulting in earlier changes (17).

Catalan Sea

The Catalan Sea, located between the eastern Iberian coast and the Balearic Islands, is a representative portion of the western Mediterranean basin and provides a valuable case study for climate change effects on Mediterranean ecosystems. Global warming is reflected regionally by a rise in sea level over the last century, an increase in surface temperature of around 1.1°C in the last 35 yr, a progressive salinisation of intermediate and deep waters and a strengthening of the stratification (17).

A likely scenario of what we can expect in the Mediterranean Sea is a considerable decrease in rainfall and wind, warmer surface waters and a prolonged stratification period. The effects on Mediterranean ecosystems are evident in (17):

• a meridionalisation of the algal, invertebrate and vertebrate species, which favours the more thermophilic species over the temperate species. Fish and benthic species from the warm waters of the southernmost parts of the Mediterranean are extending their distribution range to the north (21). More than 30 Mediterranean warm water indigenous fish species have now been recorded north of their original geographical distribution (17). Because coldwater species living in the northern and colder areas of the western Mediterranean basin cannot move farther north, they may dramatically decrease in number or even be at risk of extinction (21,22). Endemic may be replaced gradually by exotic species (23);
• mass mortality events of sessile invertebrates of the coralligenous communities owing to anomalous warm waters during the period when food is scarce. The coralligenous community is one of the best indicators of climate change in the Catalan Sea and, in general, the northwestern region of the Mediterranean Sea (24). At present, the exposure to temperatures causing physiological stress under summer low-food conditions appears to be the main cause of major mass mortality events. The exposure of organisms to lethal temperatures and susceptibility to opportunistic and pathogenic microorganisms may be come more frequent;
• increases in the smallest phytoplankton due to the prolongation of the water stratification period. In the Catalan Sea, stratification has intensified and the stratification period has lengthened over the last decades (27); the difference between the surface and deep water temperatures has increased over the last 30 years (17);
• proliferation of gelatinous carnivores, including jellyfish, due to the temperature rise and the lack of rainfall;
• a faster acidification of seawater, compared with the global oceans, accompanied by a decrease in the capacity to absorb atmospheric CO2.

It is difficult to distinguish changes associated with climate variability from those related to other anthropogenic factors, however. Climate change is an additional pressure on top of many already experienced by fish stocks, such as fishing, loss of habitat, pollution and disturbance from introduced species (25). In addition, anthropogenic pressures are found in water management on land, which affects river discharges and habitat loss, and degradation of waters and substrate necessary for fish spawning, feeding and growth (26).

Vulnerabilities - The Ebro River delta

The Ebro River delta

The Ebro Delta is located on the Spanish Mediterranean coast about 200 km south of Barcelona. It has a subaerial surface of about 330 km2 and a 50 km- long sandy coastline, formed by the sediments supplied by the Ebro River (8). The Ebro Delta is one of the most important wetland areas in the Mediterranean region, having more than 300 different species of birds (60 % of all the species in Europe), and about 515 different plant species (9). The area comprises freshwater, brackish and saline lagoons, salt marshes and coastal sandy areas.

Extensive damming in the river catchment basin has reduced the overall sediment supply to the delta (8), making it more vulnerable to wave action. Sediment supply to the deltaic plain during floods has disappeared and, as a consequence, has severely limited the vertical accretion process in the deltaic plain.

The Ebro River is the largest Spanish fluvial system. Water flow in the catchment is regulated by 187 reservoirs. Diverted water is used for agricultural irrigation, electricity production and domestic consumption. Monthly water discharge is quite irregular, with a significant decrease during last century attributed mainly to increased water use for human activities. In the Ebro in particular increased coastal erosion, reshaping of coastline, loss and flooding of wetlands, and reduced fisheries yield are foreseen (1).

It is generally recognized that the synergistic effects of subsidence of the delta, due to reduced sediment deposition, coupled with sea level rise, could be a major threat to the continued, long-term existence of the unique habitat present in the Ebro delta and, in the end, to the existence of the delta system itself. On one hand saline water wedging would be enhanced; on the other hand decreased freshwater and solid discharge and increased nutrient concentration would lead to chemical pollution, increased eutrophication, water salinity and temperature increase, finally affecting the species composition of the various microenvironments of the delta area (macrophites, benthos, fish, etc.) (1).

Not only the Ebro Delta but also conservation areas such as the Doñana marshes will suffer for climate change and their ecological richness will be reduced (2).

The impact of decreasing river flows

Climate change driven decreasing flows in the Ebro River will have a further detrimental effect on the ecological status of the lower part of the watershed (1).

A decrease in river runoff for the Ebro basin is estimated to be about 0-12% of the mean annual runoff by the year 2050, due to a reduction of precipitation in the main part of the Ebro watershed. The occurrence and magnitude of drought events might also increase, giving in turn rise to further deterioration of the watershed (exacerbating erosion), depletion of overexploited freshwater resources and decline in surface and groundwater quality (1).

Reduced flows will result in diminished diluting power in the Ebro. Thus freshwater could decrease as a consequence of decreasing flow and/or increasing discharges from agricultural fields and from treatment plants in the Ebro River. Current knowledge supports the idea that there will be a further increase in salinity in winter and spring months and an increase in phosphorous (from agricultural fields) as a consequence of the decrease in spring flows, fostering an increase of primary production in the lower reaches of the river (1).

The impact of sea level rise

According to calculations, in the absence of any climate-induced sea level rise, current (moderate) subsidence rates (0.2-0.4 m in 2100) would lead to flooding of about 26 % of the deltaic surface by 2100. When IPCC derived low (0.18 m in 2100) and high (0.59 m in 2100) sea level rise scenarios are considered, the affected surface area ranges between 45 and 61 %, respectively (10).

The significance of the existing network of channels crossing the deltaic plain in controlling delta inundation is evident. Channels conduct water through the deltaic plain from sea-connected low areas to areas lower than the target water level, but isolated by embankments. The use of floodgates could efficiently control the flooding of isolated areas, and any effective measures aimed at controlling flooding must also include management of the existing channel network (10).

The most affected habitat would be saltwater wetlands, with more than 95 % (maximum 99 %) of existing wetlands located in flood areas. The least affected habitat would be urban areas, as only about 8 % of the land would be affected in the high RSLR scenario. In absolute terms, cropland would be the most affected habitat (10).

Vulnerabilities - Sierra Nevada

When there is no possibility of quick in situ adaptation, the alternative is to migrate to favourable conditions. In Sierra Nevada, due to its island-like ecological behaviour and topographical configuration, only upwards shift is possible. Vertical shift of plant populations should be very swift so that they can maintain themselves within an optimal habitat-suitability range. This circumstance presents some problems (6):

• many species might encounter limitations when migrating upwards because their seed-dispersal abilities are limited, or due to natural or anthropogenic barriers;
• migration will depend on the potential for establishment (survival of seedlings and juveniles), this being limited by factors such as herbivory, which lowers the recruitment rate.

The extrinsic problems are a consequence of the topographical configuration. With the rise in altitude, the area of available habitat diminishes, the topography becomes more hostile (higher slopes), and the soil loses the power to sustain shrub and tree species (6).

The real challenge lies in the preservation of biodiversity of the mountain summits, since the species living there lack areas for expansion and will be subjected to great pressure, both by the degradation of the conditions appropriate to each species as well as by the arrival of new competitive species from lower altitudes (6).

Vulnerabilities - Pyrenees

An assessment was made of the impacts of climate change on the potential distribution of six alpine grasslands, two subalpine (and alpine) scrublands and four subalpine forests of Pinus uncinata in the Oriental Pyrenees by the end of the twenty-first century under the IPCC SRES A2 and B2 emissions scenarios, using one global circulation model (30). The results show that higher elevation vegetation is more vulnerable to area losses due to climate change than vegetation at lower elevations. The altitudinal extension of the Pyrenees allows scrublands and forest with a subalpine habitat suitability to move upward as the climate becomes warmer and drier. However, the alpine vegetation belt of the Pyrenees is restricted by altitude (there is no more space available at higher altitudes), which would lead to dramatic losses in appropriate areas for different vegetation units. Therefore, the impact of climate change will mainly affect alpine vegetation units (30).

For 2080 average losses in potential ranges are projected of 92.3–99.9 % for alpine grasslands, 76.8–98.4 % for subalpine (and alpine) scrublands and 68.8–96.1 % for subalpine forest. Alpine grasslands can be expected to become relegated to refuge areas (summit areas), with their current range being taken over by subalpine scrublands. Furthermore, subalpine forest units will probably become displaced and will occupy areas that currently present subalpine scrub vegetation (30).

Thus, a real challenge lies in the preservation of biodiversity of the mountain summits, since the species living there lack areas of expansion and will be subjected to great pressure, both by the degradation of the conditions appropriate to each species and by the arrival of new competitive species from lower altitudes (31). According to the assessment results, an average of 25 % of high mountain Pyrenees vegetation units is projected to lose their entire suitable area by 2080 under this climate change scenario. These results do not consider either competition phenomena or the ability of species to resist severe climatic conditions that are not lethal for their survival, however; therefore, actual loss of area of occupancy of the studied vegetation units by 2080 could be considerably lower than predicted based on the results of this work (30).

Adaptation strategies Spain

For watershed systems adaptation strategies should focus on increasing their resilience to climatic change. Given the heterogeniety in watershed types, strategies need to incorporate local needs and issues with active participation of all stakeholders. The conservation and sustainability of watersheds in the Mediterranean region is an important issue to sustain local and regional economies and ecosystems. A localized strategy that incorporates watershed characteristics and information is vital to sustain the region. A long-term strategy is needed to involve resilience enhancing measures that will enable watersheds to withstand and transform to climatic change (7).

The Ebro River Delta

Since the Ebro River does not play a significant role in supplying sediment to the deltaic plain, adaptation is considered to be a plausible option for managing the delta under sea level rise. This would mean accepting surface area losses and/or changes in land use in the lowest parts of the Ebro Delta, where natural values will be reinforced, and concentrating agriculture in the higher parts of the deltaic plain (10).

Mediterranean Sea

The following actions need to be taken (17):

• Reduce the effect of those disturbing factors we are more able to control (overfishing, destruction of habitats, pollution) and that may act synergistically with climate change to the detriment of marine eco – systems;
• Monitor the main physical, chemical and biological variables that are indicators of climate and environmental changes and the speed at which they are occurring;
• Investigate the mechanisms and processes through which climate change acts on marine populations.

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Spain.

1. Eisenreich (2005)
2. Oficina Española de Cambio Climático (2008)
3. Government of Spain. Quinta Comunicación Nacional de España
4. Comisión de Coordinación de Políticas de Cambio Climático (2007)
5. Fornes et al. (2000), in: European Environment Agency (EEA) (2009)
6. Benito et al. (2012)
7. Erol and Randhir (2012)
8. Guillén and Palanques (1997), in: Alvarado-Aguilar (2012)
9. Espanya (1997), in: Alvarado-Aguilar (2012)
10. Alvarado-Aguilar et al. (2012)
11. Poulard & Blanchard (2005), in: Chust et al. (2011)
12. Désaunay et al. (2006), in: Chust et al. (2011)
13. Clemmesen et al. (2007), in: Chust et al. (2011)
14. Drinkwater et al. (2010), in: Chust et al. (2011)
15. Steinacher et al. (2009), in: Chust et al. (2011)
16. Chust et al. (2011)
17. Calvo et al. (2011)
18. Bethoux et al. (2002), (2005), both in: Calvo et al. (2011)
19. Rixen et al. (2005), Touratier and Goyet (2009), both in: Calvo et al. (2011)
20. Coll et al. (2010), in: Calvo et al. (2011)
21. CIESM (2008a), in: Calvo et al. (2011)
22. Ben Rais Lasram et al. (2010), in: Calvo et al. (2011)
23. Ben Rais Lasram and Mouillot (2009), in: Calvo et al. (2011)
24. Ros (2009), in: Calvo et al. (2011)
25. Brander (2010), in: Calvo et al. (2011)
26. de Juan and Lleonart (2010), in: Calvo et al. (2011)
27. Coma et al. (2009), in: Calvo et al. (2011)
28. Rixen et al. (2005), Vargas-Yáñez et al. (2010), both in: Calvo et al. (2011)
29. Vargas-Yáñez et al. (2007), in: Calvo et al. (2011)
30. Pérez-García et al. (2013)
31. Benito et al. (2011), in: Pérez-García et al. (2013)
32. Fernández (2011), in: IPCC (2014)
33. Scheffer et al (2015)
34. Guardiola-Albert and Jackson (2011), in: Scheffer et al (2015)
35. Adloff et al. (2015)
36. Guiot and Cramer (2016)
37. Hidalgo-Galvez et al. (2018)
38. Soto (2018)