Vulnerabilities - Marine, estuarine and intertidal biodiversity

The biodiversity of coastal environments is mainly affected by sea level rise, realignment of sea defences, temperature rise, and storm sewage.

Sea level rise

Rising sea levels may affect the shape of estuaries, particularly where isostatic subsidence is occurring (as in the East of England). This will determine intertidal sediments and hence the numbers of waterbirds an estuary can support. Besides, sea level rise will encourage erosion of many salt marsh, sand dune and vegetated shingle areas, especially if coupled with increases in storm activity.

Climate change is likely to introduce additional stress on coastal habitats, especially within the southern part of Britain where the highest rises in sea level are predicted to occur (1).The anticipated impacts of climate change and sea-level rise for London’s intertidal habitat include increased levels of inundation and storm flooding; accelerated coastal erosion; sea water intrusion into freshwater tributaries; changes to the tidal prism, tidal range, sediment supply and rates of accretion; changes in air temperature and rainfall affecting growth of salt marsh plants with secondary effects on sedimentation (2).

Managed realignment of sea defences

This may result in more extensive intertidal flats at the expense of marshes. This is likely to lead to detrimental changes in habitat quality for most species. Loss of salt and freshwater marshes due to coastal squeeze is likely to be a serious problem for water birds, in particular those species that do not feed on the intertidal flats (1). Managed realignment of salt marsh and coastal grazing marsh could lead to significant habitat gains and losses, respectively (3).

Temperature rise

Warmer weather expected with climate change is likely to drive further changes in wader distributions. As winters in Britain become milder a greater proportion of the East Atlantic Flyway populations of some species may over-winter further north and east on the continent of Europe (1). Climate change was shown to affect Britain’s overwintering water bird population in two main ways: firstly, through the direct effect of changes in (severe) weather on water bird distributions and their invertebrate prey; second, through the indirect effect of rising sea levels on the availability and nature of coastal habitats (2).

Storm sewage

One of the most significant threats to the biodiversity of the intertidal habitat of the lower Tidal Thames is currently the flushing of storm sewage from London’s Victorian sewers during intense summer storms (2). Situated at the highly dynamic interface between land and sea, intertidal zones are some of the world’s most diverse and productive environments. The lower Tidal Thames is no exception, supporting as it does about 120 species of fish, 350 freshwater, estuarine and marine macroinvertebrate species, and nearly 300,000 over-wintering water birds (4).

Areas of intertidal habitat are present along the entire length of the Tidal Thames, but the most extensive reaches are below Tower Bridge where the flood defences are set further back from the main channel (4).

Vulnerabilities - Fresh water and wetlands biodiversity

The biodiversity of fresh water and wetlands is mainly affected by extreme low summer flow events, intensity of storm events, invasive species, and the impact of droughts on wetlands.

More extreme low summer flow events

Lower flows combined with higher temperatures and concentrated nutrient loads may decrease dissolved oxygen levels and increase eutrophication (5).

Increased intensity of storm events

Scour of river banks is expected to increase (dry catchment soils will be more susceptible to erosion exacerbating this issue), collect more urban and agricultural pollution and hence contribute more sediment and pollution to water bodies (5).

More favorable conditions for invasive species

Climatic changes that create conditions favorable for invasive species may increase the impacts on more than just the indigenous species they displace. Aquatic weeds such as Eichhornia crassipes (Water Hyacinth), Crassula helmsii (Australian Swamp Stonecrop), Azolla filiculoides (Water Fern) and Lagarosiphon major (Curly Waterweed) form dense mats or stands that may block water industry infrastructure and irrigation, navigation and river channels (5).

The impact of droughts on wetlands

Inland semi-natural lowland ecosystems are generally likely to be less vulnerable to climate change than coastal ecosystems. However, wetlands such as the internationally important raised bogs at Cors Erdrreiniog on Anglesey and Cors Tregaron in mid-Wales are exceptions. Their ecological characteristics and contribution to biodiversity depend primarily on retaining year-round water saturation.

This may be compromised by hotter, drier summers, and especially by droughts, which are predicted to become more frequent. The predicted wetter winters are unlikely to offset the damaging effects of drought significantly and existing management to counteract the effects of past drainage may need to be enhanced to cope with the extra drought stress (6).

Summer drought interacting with higher temperatures might set in train the irreversible drying out and subsequent oxidation and breakdown of peat. This could lead to wide-ranging ecological impacts, including dramatic changes in the vegetation cover of moorland areas and the loss of many plant and animal species(6). East Anglia may lose species in fens and blanket and raised bogs that are sensitive to moisture, although increased flood risk in the Fens could represent opportunities such as wet heath re-creation, and lead to expansion of coastal grazing marsh (3). Management issues, however, are critical here and a net overall loss for the region is thought to be likely.

Vulnerabilities - Terrestrial biodiversity

Biodiversity in the East Midlands is already under tremendous pressure (16). In the West Midlands, especially lowland habitats are vulnerable since they are typically small and isolated whereas there are extensive moorlands and acidic grasslands in the uplands (17). The general impact of climate change for Scotland is not drastic, despite threats to some coastal and mountain species, and naturalists can be confident that many interesting organisms will persist (18). It has been stated that many of the species on the UK Biodiversity Group's Priority List will either be little affected by climate change, or may respond positively to it (18).

The terrestrial biodiversity is mainly affected by changing patterns of vegetation types, the sensitivity of species with a northern distribution, the response of plant, insect and amphibian species, and habitat fragmentation and isolation.

Changing patterns of vegetation types

This includes the loss of xeric (dry) woodlands/scrub, a reduction of boreal (northern) evergreen forests and temperate conifer forests and an expansion of temperate deciduous forest and temperate/boreal mixed forest at the national scale.

From a study for East Anglia and North West England it was concludedthat East Anglia probably remains predominantly covered by temperate deciduous forest in the 2050s, whereas in North West England temperate conifer forest is almost lost from around one third of the area and is replaced by a mixture of temperate deciduous forest and temperate/boreal mixed forest, depending on the climate change scenario (3).

The sensitivity of species with a northern distribution

The sensitivity to climate change of Arctic-Alpine habitat and other species with a northern distribution will result in a loss of these species. This loss is critical and although it could be balanced by species migrating northwards or to higher altitudes, the species may not be of such conservation importance.

On the whole, there could be favorable conditions for upland hay meadows, bogs and, particularly, salt marshes, while changes in lowland agriculture could adversely affect other habitats (8). Upland ecosystems, notably arctic-alpine plant and invertebrate communities, are likely to be particularly vulnerable to the effects of climate change as climate and associated soil characteristics are primary factors influencing their development and stability (7). Conversely, some vegetation types are likely to benefit from warmer, drier summers.

The response of plant, insect and amphibian species

The response of plant, insect and amphibian speciesto climate change will be (highly) variable.The range of some plant species could decline whilst others could expand. Generally plants and insects with a southern distribution are likely to gain climate space. The response of bird species is also likely to be highly variable. For example, Nightingale and Nuthatch may show a positive response to moderate climate change, but with severe climate change their distributions may either contract significantly or become fragmented in southern and eastern England (1).

Habitat fragmentation and isolation

These are likely to be of key importance, but we know little or nothing about their effects on most species. Thus, while we may be reasonably confident that artificial barriers such as cultivated arable land or urbanized land will form effective barriers to the migration of many species associated with semi-natural habitats, we have little knowledge of which species will be affected most seriously and why (7).

The loss of terrestrial biodiversity results in damage to ecosystem services, loss of carbon storage in peat soils, reduction in soil quality, and increased risk of invasive species taking hold (9). Also, species are lossed from reserves (10). Reserves set aside for particular groups of species are fixed in space, but the species currently found there may not thrive under new climatic conditions, resulting in overall species loss and local extinction. Nature Reserves established with particular rare species may lose that species if vulnerable to climate change or to consequences of climate change (e.g. fire incidence; drought incidence). Some regional Species Recovery programmes may be put at risk if the more extreme climate scenarios become reality (10).

Vulnerabilities - Birds

From abundance data from citizen science bird surveys in the UK and France spatial patterns of future climatic suitability throughout Great Britain were projected for 124 breeding bird species. It was concluded that climatic suitability of Great Britain will increase for 44% of these species and decline for 9% of these species by 2080 (22). 

Vulnerabilities - Phenological change and ecosystem functioning

There has been broad unanimity that spring events in the northern hemisphere have become earlier, with estimated mean advances ranging from 2.3 days per decade (19) to 5.5 days per decade (20). Phenological change and its relationship with climate change has been studied for UK terrestrial, freshwater and marine taxa between 1976 and 2005 (21).

Phenological records included dates of flowering and leafing, plankton population growth, insect flight periods, births and migration. The analysis included data from across the whole United Kingdom. During this period, the seasonal timing of biological events in all major taxonomic groups in UK terrestrial, freshwater and marine environments advanced, on average, by 0.39 days per year (equivalent to 11.7 days over the whole period). Overall, 83.8% of phenological trends were towards earlier seasonal timing. Leafing, flowering and fruiting dates of terrestrial plants showed the most rapid mean rate of change (0.58 days per year) and the highest percentage of advancing trends (92.5%) (21).

The majority of spring and summer events have advanced, and more rapidly than previously documented. Furthermore, average rates of change have accelerated in a way that is consistent with observed warming trends. According to the researchers a broad scale signal of differential phenological change among trophic levels was shown; across environments advances in timing were slowest for secondary consumers, thus heightening the potential risk of temporal mismatch in key trophic interactions. The researchers state that, if current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of many ecosystems and having a major impact on ecosystem services (21).

Vulnerabilities - Regional differences

West and Gawith (5) present an overview of expected climate change impacts on several activities for different regions of the United Kingdom, based on several regional scoping studies.

The results for biodiversity are listed below. A blank cell indicates that no specific issues were identified for the region besidesthose noted in the first row. Each region identified and discussed issues differently, so this table might not provide comprehensive coverage of all issues.

Region Expected positive impact on biodiversity Expected negative impact on biodiversity Uncertain impact on biodiversity Majority of regions Species and habitats may be gained Species and habitats may be lossed. Intertidal habitats, salt marshes and mudflats threatened   South West   Loss of species at southern edge of their range. Local extinction of species that migrate away from nature reserves   South East     Gardeners may adapt plantings to cope with drought. Use of 'zero-water' gardens London   Competition form exotic species. Increased summer drought stress for wetlands and beechwood   East of England Species gained Species lost. Coastal habitats vulnerable to coastal squeeze, flooding and erosion. Flooding of Fens   East Midlands     Earlier growth of vegetation sensitive to late frosts. Longer breeding season for some species West Midlands Wetter winters benefit biodiversity in wetland areas     Wales   Raised bogs might dry out   North West   Rural uplands will see significant impacts Change in viability of peat as a carbon sink Yorkshire % Humber   Estuarine and river ecology threatened by tidal flooding. Increased bracken invasion. Increased fire risk on heathlands   North East   Important habitats such as relic alpine heath threatened   Scotland   Negative impact on mountain birds and subantarctic and arctic alpine plant species; natural environment is the sector most affected by change   Northern Ireland   Invasion of southerly species. Compounded effects of negative factors such as eutrophication  

Interaction climate change and other factors

Amajor unknown which currently bedevils all attempts to devise effective management of climate change impacts is our lack of understanding of the effects of interactions between climate change and other key factors affecting biodiversity (7).

Upland land use (especially intensity and pattern of sheep grazing), and soil and water acidification and eutrophication arising from atmospheric nitrogen deposition, are two of these factors. Elevated concentrations of atmospheric carbon dioxide may lead to wide-ranging enhancement of plant biomass production, which might enable lower stocking densities without reduction of livestock production. Both factors are likely to have large impacts upon diversity, but we have little understanding of which communities and species will be affected or how.

Integrated assessments are important (3): changes in agriculture, water resources and coastal processes have a significant effect, possibly over-riding short-term effect on the ability of species and habitats to cope with climate change. Lowland heathland in East Anglia, for instance, should be able to maintain its species composition, but its existence is under pressure from agriculture. The cereal field margin species, however, are more dependent on cropping practices, while the upland hay meadows would be affected by moves away from low intensity agriculture.Agricultural changes resulting from adaptation response to anticipated climate change could have a profound effect (positive or negative) on biodiversity (10).

Adaptation strategy - Marine, estuarine and intertidal biodiversity

The coastal habitats, especially those associated with offshore sand banks and salt marshes, sand dunes, and estuaries are in many cases very vulnerable to sea level rise, especially if it is rapid and associated with increased storminess. In some places there may be opportunities for managed retreat leading to replacement of lost habitats, but in others this will not be an option (7). It is recommended to adopt erosion setback requirements and increase shoreline buffers to protect against increased runoff from more intense storms (11).

Biodiversity is strongly influenced by land use, and so policy responses should be developed in terms of integrated marine and coastal zone management. The sector should apply similar criteria to coastal areas of nature conservation importance in respect of protection against sea level rise, as it calls upon others to apply to areas for development or agriculture (viz. avoid calls for unsustainable coastal protection) (10).

Adaptation strategy - Terrestrial biodiversity

Several options are presented in the scientific literature for adapting terrestrial biodiversity to climate change.

Examples of actions include a habitat restoration project in the Fenlands through a partnership of public sector bodies and NGOs, which aims to restore 3000 hectares of fenland over 50 years (12). Where possible loss of habitats should be compensated by creation of similar habitats in less vulnerable areas. Opportunities should be indentified to create new habitats and landscapes as a result of climate change and create corridors and stepping stones to allow species to adapt and migrate (11,13). ‘Green corridors’, such as river corridors and railway lines, may be important for species migration, and should be protected (4). A more forward-looking, flexible and dynamic approach to nature conservation is required to accommodate climate change, involving habitat management and landscape-scale responses (10).

Biodiversity is strongly influenced by land use, and so policy responses should be developed in terms of integrated land-use management. Reorganization of agriculture can and will provide opportunities for nature conservation objectives to be realized, provided climate change effects are taken into account (10).

Green spaces in low-lying areas should be created and protected that might serve for flood management, plant diverse trees species and shrubs with a broad range of environmental tolerance, and enhance conditions for street tree survival and growth (increase space for roots, control soil compaction, increase watering and maintenance) (11).

Pests and invasive species that can expand with warmer winters should be monitored and controlled (11).

One approach to protect declining wildlife and plant populations is to establish reserves or designated areas. Unfortunately, 10% of all UK nature reserves could be lost within 30-40 years, and species distributions could change significantly in 50% of designated areas in the same period (14). Moreover, nearly all land suitable for designation is already protected. Planners should recognise biodiversity hotspots (15) – areas containing concentrations of endemic species facing extraordinary threats of habitat destruction.

Other options include captive breeding and translocation programmes for endangered species, but no techniques currently exist for translocating intact biological communities (even space permitting) (2).

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 the United Kingdom.

1. Land Use Consultants, CAG Consultants and SQW Limited (2003b)
2. London Climate Change Partnership (2002)
3. Holman et al. (2002)
4. Environment Agency (2001), in: London Climate Change Partnership (2002)
5. West and Gawith (2005)
6. ICF International and RPA (2007)
7. Farrar and Vaze(2000)
8. Holman et al. (2000)
9. Defra (2008)
10. C-CLIF and GEMRU (2003)
11. Clean Air Partnership (2007)
12. Department for Environment, Food and Rural Affairsof the United Kingdom (2006)
13. Land Use Consultants, CAG Consultants and SQW Limited (2003a)
14. DETR (1999), in: London Climate Change Partnership (2002)
15. Myers et al. (2000), in: London Climate Change Partnership (2002)
16. Kersey et al. (2000)
17. Anderson et al. (2003)
18. Kerr et al. (1999)
19. Parmesan and Yohe (2003), in: Thackeray et al. (2010)
20. Root et al. (2003), in: Thackeray et al. (2010)
21. Thackeray et al. (2010)
22. Massimino et al. (2017)