Information and Advisory Note Number 111 Back to menu
Impacts of climate change on plants, animals and ecosystems in Scotland
1. Introduction
1.1 Human-induced global change is now widely perceived to be becoming apparent.
This change will have an effect on habitats and species throughout the world.
Large changes are expected over a period of the next one or two centuries. This
timescale is similar to the lifespan of many organisms, notably trees and
people. It is short in comparison with the time over which communities and soils
have developed. Wise stewardship requires an awareness of the likely magnitude
of change and of its consequences for the natural environment.
2. Predicting climate change
2.1 Predictions of climate change are each based on an emissions scenario,
specifying the levels of greenhouse gas emissions over time, combined with a
general circulation model (GCM) of the global atmosphere and oceans. Both
emissions scenarios and GCMs incorporate many assumptions, which make climate
change predictions uncertain. In spite of this, there is increasing agreement
among climate modellers about the direction and magnitude of future climate
change. Predictions in this l&A Note are based mainly on the internationally
agreed IS92a emissions scenario. According to IS92a the present day
concentration of C02 will double to about 700 parts per million by 2100. The GCM
is the HADCM2, which is
a coupled ocean-atmosphere model.
Details are given in the box below.
2.2 By 2050, average temperatures in all regions of Scotland are likely to be
1°C warmer than in 1990 (Table 1). The limits of uncertainty are such that the
minimum expected change is approximately 0.5°C, while an upper bound of warming
might be 1.5°C by 2050.
2.3 Wetter conditions are likely - about 10% by 2050 - although there will be
strong seasonal differences. The greatest increase in precipitation will be in
the autumn, while a decrease may occur in spring. Predicted changes in
precipitation also differ greatly between the wet and dry parts of Scotland.
2.4 Wind speeds are predicted to increase. Greater cloud cover will reduce solar
radiation by approximately 3% and by up to 6% by 2100.
Table 1. Climate change scenario for Scotland based on IS92a and HADCM2; values
are annual means of Meteorological Stations in Scotland (from Climatic Research
Unit, Norwich and UK Met Office). Wind speed is the change in mean annual wind
speed 10 m above the ground; the present average for Scotland is about 7 m/s.
Radiation is the mean annual rate of energy input from solar radiation expressed
in watts per square metre; the present average for Scotland is about 80 Wm'2.
Carbon dioxide is given as a concentration, not a change, in parts per million.
2.5 Predictions for 2100 continue the same trend (Table 1) so that Scotland is
likely to become warmer, wetter and with an even less predictable climate!
2.6 Global sea-level rise by 2100 is predicted to be about 46 cm. Actual
sea-level rise in much of Scotland will be less because of continued uplift
following melting of ice at the end of the last glacial period (Figure 1).
2.7 It is not anticipated that a cessation in the Atlantic thermohaline
circulation (the North Atlantic Drift) will occur in the next 100 years. Such a
cessation would produce very strong cooling in Scotland even while global
average temperatures rose. Models indicate that the earliest time at which such
cooling might occur would be in the 22nd century.
3. Character of Scotland's future climate
3.1 In broad terms the changes described above are towards greater warmth and
oceanicity. The changes predicted for 2100 can be visualized by looking for
climates elsewhere in the British Isles that resemble future climates of
Scotland. Most future Scottish climates have good present analogues in southern
Britain and Ireland. In 2100, the predicted climate of Aberdeen will resemble
the present climate of Anglesey and that of Paisley will be like the present
climate on the southern edge of Dartmoor. The west coast of Scotland will have
climates resembling those currently experienced in the west of Ireland.
3.2 Analogue climates are depicted as maps in Figures 2 and 3. The matching of
climate to calculate similarity of analogues was based on four variables, summer
temperature, winter temperature, annual precipitation and summer precipitation.
It will become warmer so that
the present analogues are about 600 km further south, and more oceanic so that
the best present analogues of east-coast sites such as Leuchars are in the
southwest. It is likely that the east coast, with its relatively cold springs
and tendency to sea fog will retain some of its character.
4. Adaptation and dispersal in response to climate change
4.1 Species' response to change is through dispersal, death, invasion and
displacement. Small genetic adjustments, for example in timing of hatching, are
possible for short-lived organisms such as insects and some migrating birds.
4.2 Species behave individualistically. Communities are assembled from the
species
that are available and hence cannot themselves disperse to new localities. Some
organisms, including many birds, bryophytes and aphids, have effective means of
dispersal, allowing them rapidly to reach newly available habitat. Others can be
much delayed.
4.3 For most plants and animals, the sea is a major barrier, so that the
existing species pool of Britain will not change much in the next 100 years. Any
Scottish invaders are likely to be present already in England or Wales. This may
not, however, be true for fungal spores that are known to be capable of
dispersal over very large distances.
5. Impacts on habitats
5.1 The predicted rise in sea level is not large enough to have any significant
impact on hard coasts. On soft coasts the shoreline may move inland. Where
coastal defences are constructed to combat this, parts of saltmarshes and dunes
may be lost.
5.2 Impacts on freshwater habitats are generally likely to be much less than
those that have been brought about by chemical changes such as acidification and
eutrophication or physical changes such as low flow due to water abstraction.
5.3 The effects on alpine and subalpine habitats of a 1.8°C rise in temperature
are roughly equivalent to a 300 m decrease in altitude. This will have many
adverse effects, including loss of persistent snow patches, reduced solifluction
and invasion of more competitive plants and animals from lower altitudes. Higher
windspeeds may offset the effects of rising temperature on extensive open
habitat at high altitudes.
5.4 In many other habitats, effects on animals and plants are likely to result
from land management practices, rather than directly from climate change. Tree
growth will benefit both from increased temperatures and from higher levels of
C02, but this could be counteracted by reduced radiant energy. Caledonian forest
(Figure 4), in some places, is likely, as the balance between boreal and nemoral
forest, changes be subject to increased invasion by oaks. The peat of raised
bogs and blanket bogs will continue to grow.
6. Impacts on species
6.1 The effects on many marine animals such as cetaceans and basking sharks are
not likely to be large or adverse. Most of these can exist in warmer waters to
the south of Scotland. Effects on freshwater animals are also for the most part
likely to be small.
6.2 Terrestrial mammals, being relatively large robust homeotherms, are affected
more by availability of food and habitat than by direct effects of temperature.
6.3 Warmer winters with shorter periods of frost and snow may attract larger
numbers of overwintering birds. Migrants will undoubtedly be affected by changes
in wintering and staging areas in Scotland and elsewhere, but prediction is
almost impossible. The effects of climate change on mountain birds, notably
ptarmigan, dotterel and snow bunting, will undoubtedly be negative. The snow
bunting depends directly on snow as a habitat and may become extinct in
Scotland.
6.4 Terrestrial invertebrates are highly sensitive to temperature, which affects
their numbers, breeding success and timing. For those insects that
thermoregulate by basking, the predicted climate scenario has opposing effects.
Warmer mean temperatures will generally be beneficial, while reduced radiation
will have a negative effect. However, the fact that several of the rare
day-flying insects are at present found in the west of Scotland suggests that
factors other than temperature and insolation play a role. For many insects and
other invertebrates with an annual life cycle, or with several annual cycles, we
might expect to see genetic adaptation to the new climatic conditions. However,
it remains unknown whether the coupling between predators and prey and between
hosts and parasites will remain fully intact.
6.5 Lichens with a southwestern distribution in Britain should extend their
range in Scotland. Increasing warmth and moisture, however, can be expected to
have a negative influence on many other species. Slug grazing will intensify,
lignum will rot faster and competing algae and bryophytes will become more
vigorous. Eastern lichens of lowland trees, a strongly declining group even
under the present climate, are particularly threatened.
6.6 The oceanic bryophytes of western
Scotland are a notable component of the
country's natural heritage. For most of them,
the scenario is either favourable or broadly
neutral. A few species, such as
Anastrophylium donnianum and Scapania
nimbosa, that require cold conditions may
disappear from some sites. Among
bryophytes that do not have oceanic
distributions, losses of montane species, such
as Scorpidium turgescens and Stegonia
latifolia, are almost inevitable.
6.7 Except for mountain plants and a few eastern species such as twinflower
Linnaea borealis (Figure 5) and wood cow-wheat Melampyrum sylvaticum, the
distribution of vascular plants should either remain stable or increase in
response to climate change. The few remaining stands of subarctic dwarf-shrub
willows appear to be moribund at present and will almost certainly not be able
to establish populations at higher altitudes.
6.8 Arctic-alpine species, such as Norwegian mugwort Artemisia norvegica and
drooping
saxifrage Saxifraga cernua, are under threat; many of them exist in north-facing
corries, so they will be directly affected by the increase in ambient
temperature and will be little affected by reduced sunshine. Losses are almost
inevitable.
6.9 The diversity of the lowland flora can be expected to increase, as southern
species move northwards. However, there is only a small species pool of
calcifuge southern species that might occur on acid peaty soils, so few species
will invade acid moorland. Specialists of Caledonian forest, such as
one-flowered wintergreen Moneses uniflora and creeping lady's-tresses Goodyera
repens, would be under long-term threat if the habitat converts to broadleaved
woodland, but management to conserve pine forest will almost certainly ensure
the continued existence of these woods and their constituent species of plants
and invertebrates.
7. What can we do about climate change?
7.1 Responses to combat the causes of change are being taken by national
governments. In spite of these, greenhouse gas emissions can be expected to
increase
world-wide, and there is little reason to think that the IS92a scenario is
unrealistic.
7.2 Because of the pervasive nature of global change, actions to mitigate its
effects can only be relatively limited. Maintenance of grazing and, in
exceptional cases, soil disturbance may help to keep communities open and
suppress vigorous southern species. There is little that can be done to preserve
many species requiring prolonged snow-lie short of adding snow to selected snow
patches.
7.3 In non-urban areas, habitat creation through managed retreat may be an
effective response to sea-level rise, although it would be at the expense of
low-lying coastal land.
7.4 With vascular plants and some larger animals, it may be possible to control
competitors. Management of Caledonian forest by selection for pines is an
example of this, as is control of rhododendron in western oak woods.
7.5 Translocation has been widely used as a means of establishing new colonies
of vertebrates such as predatory birds, sand lizards and deer. A few
invertebrates, including wood ants and some butterflies have also had new
populations established by translocation.
7.6 The most effective response is to
maintain appropriate management to combat
habitat degradation. This amounts to
continuing with good practice rather than
deliberate attempts to counteract the
consequences of climate change. It also
implies that the objectives of managing a
particular habitat type are clearly stated so
that management activity can be altered to
conserve the habitat type, and its component
species.
8. Issues for conservation strategy
8.1 The climate change scenario for the next century is not drastic. Naturalists
can be confident that many interesting organisms will persist. Indeed, many,
perhaps most, 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.
8.2 However, it is pertinent to raise a number of questions that will need to be
answered.
• Which habitats can be managed to maintain their condition under climate
change?
• Which habitats should be allowed to undergo natural succession or change as a
result of climate change?
• Is it worth attempting to save arctic-alpine species given that change will
continue beyond 2100?
• Are there opportunities for habitat creation and for managed retreat in
particular?
• Where, and under what circumstances, will it be practical to control
competitors and predators?
• What opportunities are there for translocation?
• Is there adequate monitoring in place to ensure that the effects of global
change are observed in time to undertake mitigating action?
9. Further reading
DETR (1998) Climate Change Impacts in the UK: the Agenda for Assessment and
Action. Department of the Environment, Transport and the Regions, London.
Hill, M.O., Downing, T.E., Berry, P.M., Coppins, B.J., Hammond, P.S., Marquiss,
M., Roy, D.B. Telfer, M.G. & Welch, D. (1999) Climate Changes and Scotland's
Natural Heritage: an Environmental Audit. SNH Research, Survey and Monitoring
Report No. 132. Scottish Natural Heritage, Battleby.
Hodder, K.H. & Bullock, J.M. (1997). Translocations of native species in the UK:
implications for biodiversity. Journal of Applied Ecology, 34, 547-565.
Houghton, J.T., Meira Filho, L.G., Callander, B.A., Harris, N., Kattenberg, A. &
Maskell, K. (ed.) (1996) Climate change 1995: the science of climate change.
Cambridge University Press, Cambridge.
Huntley, B. (1991) How plants respond to climate change: migration rates,
individualism and the consequences for plant communities. Annals of Botany, 67 (Suppl.
1), 15-22.
Tooley, M. .& Jelgersma, S. (eds) (1993) Impacts of Sea-level Rise on European
Coastal Lowlands. The Institute of British Geographers, Special Publication
Series. Blackwell, Oxford.
United Kingdom Climate Change Impacts Review Group (1996) Review of the
Potential
Effects of Climate Change in the United Kingdom. HMSO, London.
10. Acknowledgements
This l&A Note is based on a report commissioned by SNH (Hill era/., 1999). We
thank our collaborators for their expert contributions.
11. Authors
Mark Hill and David Roy
Institute of Terrestrial Ecology
ITE Monks Wood
ABBOTS RIPTON
Huntingdon
Cambridgeshire
PE17 2LS
Tel: 01487 773381 Email: m.hill@ite.ac.uk
12. Contact for advice and information
Dr Noranne Ellis
Scientific Liaison Officer
Chief Scientist's Unit
Scottish
Natural Heritage
2 Anderson Place
EDINBURGH
EH6 5NP
Tel: 0131-447 4784 Fax: 0131-446 2405
APPENDIX OF SPECIES THAT OCCUR IN SCOTLAND
Species that might become more widespread and/or more abundant
Striped dolphin
Bottlenose dolphin
Loggerhead turtle
Green turtle
Leatherback turtle
Kemp's ridley turtle
Fan mussel
Native oyster
Tall sea pen
Pipistrelle bat
Nightjar
Cirl bunting
Roseate tern
Song thrush
Allis shad
Twaite shad
Sand lizard
Natterjack toad
Great crested newt
Tadpole shrimp
Medicinal leech
Wall butterfly
Speckled wood butterfly
Donacia aquatica (reed beetle)
Melanapion minimum (a weevil)
Procas granulicollis (a weevil)
Lipsothrix nervosa (a cranefly)
Lipsothrix ecucullata (a cranefly)
Lipsothrix errans (a cranefly)
Narrow-bordered bee hawk moth
Barred toothed stripe moth
Hypocreopsis rhododendri (a fungus)
Arthothelium dictyosporum (a lichen)
Arthothelium macounii(a lichen)
Bellemerea alpha (a lichen)
Pseudocyphellaria norvegica (a lichen)
Acrobolbus wilsonii (a bryophyte)
Bartramia stricta (a bryophyte)
Lejeunea mandonii(a bryophyte)
Petalophyilum ralfsii (a bryophyte)
Foxtail stonewort
Floating water-plantain
Dune gentian
Sea lavender
Marsh clubmoss
Killarney fern
Species that might become less widespread and/or less abundant
White whale
White-sided dolphin
White-beaked dolphin
Narwhal
Red squirrel
Dotterel
Ptarmigan
Red-necked phalarope
Snow bunting
Black grouse
Capercaillie
Vendace
Arctic charr
Horse mussel
Narrow-mouth whorl snail
Round-mouth whorl snail
Geyer's whorl snail
Narrow-headed wood ant
Formica lugubris (a wood ant)
Northern brown argus butterfly
Chequered skipper butterfly
Small mountain ringlet butterfly
Great yellow bumble bee
Osmia uncinata (a mason bee)
Osmia parietina (a mason bee)
Apion rye's (a weevil)
Ceutorhynchus insularis (a weevil)
Blera fallax (a hoverfly)
Hammerschmidtia ferruginea (a hoverfly}
Rhabdomastix hilaris (a cranefly)
Thereva lunulata (a stiletto fly
Dark bordered beauty moth
Cousin german moth
Netted mountain moth
Northern dart moth
New Forest burnet moth
Slender Scotch burnet moth
Brachyptera putata (a stonefly)
Chrysura hirsuta (a ruby-tailed wasp)
Clubiona subsaltans (a spider)
Boleotopsis leucomelaena {a fungus)
Hygrocybe calyptraeformis (a fungus)
Hygrocybe spadicea (a fungus)
Tulustoma niveum (a fungus)
Hydnelloids spp (a fungus)
Alectoria ochroleuca {a lichen)
Bacidia incompta (a lichen)
Caloplaca luteoalba (a lichen)
Caloplaca nivalis {a lichen)
Catapyrenium psoromoides (a lichen)
Cladonia botrytes (a lichen)
Gyalecta ulmi(a lichen)
Hypogymnia intestiniformis (a lichen)
Peltigera lepidophora (a lichen)
Pertusaria bryontha (a lichen)
Schismatomma graphidioides (a lichen)
Thelenella modesta (a lichen)
Adelanthus lindenbergianus (a bryophyte)
Andreaea frigida (a bryophyte)
Bryoerythrophyllum caledonicum (a bryophyte)
Bryum calophyllum (a bryophyte)
Bryum neodamense (a bryophyte)
Bryum uliginosum (a bryophyte)
Buxbaumia viridis (a bryophyte)
Conostomum tetragonum (a bryophyte)
Didymodon mamillosus (a bryophyte)
Drepanocladus vernicosus {a bryophyte)
Herbertus borealis (a bryophyte)
Orthotrichum obtusifolium (a bryophyte)
Pohlia scotica (a bryophyte)
Polytrichum sexangulara (a bryophyte)
Sphagnum bafticum (a bryophyte)
Sphagnum skyense (a bryophyte)
Bird's nest stonewort
Shetland pondweed
Norwegian mugwort
Shetland mouse-ear
Mountain scurvygrass
Scottish scurvygrass
Euphrasia campbelliae (an eyebright)
Hieracium Sect. Alpestria (Shetland hawkweeds)
Common juniper
Twinflower
Small cow-wheat
Sibbaldia
Irish lady's-tresses
Oblong woodsia
Species that are unlikely to be affected
Minke whale
Sei whale
Blue whale
Fin whale
Common dolphin
Atlantic right whale
Pilot whale
Risso's dolphin
Northern bottlenose whale
Humpback whale
Sowerby's beaked whale
Gervais' beaked whale
Killer whale
Harbour porpoise
Sperm whale
Cuvier's whale
Basking shark
Water vole
European otter
Brown hare
Skylark
Linnet
Corncrake
Reed bunting
Wryneck
Scottish crossbill
Common scoter
Corn bunting
Spotted flycatcher
Tree sparrow
Grey partridge
Bullfinch
Sturgeon
Crayfish
Tenellia adspersa (a sea slug)
Freshwater pearl mussel
Scottish wood ant
Pearl bordered fritillary butterfly
Marsh fritillary butterfly
Northern colletes bee
Bembidion testaceum (a ground beetle)
Cicindela hybrida (a tiger beetle)
Cryptocephalus primarius (a leaf beetle)
Cryptocephalus dercemmaculatus (a leaf beetle)
Cryptocephalus sexpunctatus (a leaf beetle)
Dromius quadrisignatus (a ground beetle)
Dryschirius angustatus (a ground beetle)
Hydroporus rififrons (a water beetle)
Meotica anglica (a rove beetle)
Perileptus areolatus (a ground beetle)
Rhynchaenus testaceus (a jumping weevil)
Thinobius newberyi(a rove beetle)
Heptagenia longicauda (a mayfly)
Microglossum olivaceum (a fungus)
Catillaria aphana (a lichen)
Collema dichotomum (a lichen)
Gyalideopsis scotica (a lichen)
Halecania rhypodiza (a lichen)
Opegrapha fumosa (a lichen)
Opegrapha paraxanthodes (a lichen)
Bryum turbinatum (a bryophyte)
Bryum warneum (a bryophyte)
Campylopus setifolius (a bryophyte)
Ditrichum plumbicola (a bryophyte)
Jamesoniella undulifolia (a bryophyte)
Orthodontium gracile {a bryophyte)
Orthotiichum gymnostomum (a bryophyte)
Pictus scoticus (a bryophyte)
Plagiothecium piliferum (a bryophyte)
Baltic stonewort
Bearded stonewort
Lesser bearded stonewort
Mossy stonewort
Slender stonewort
Slender naiad
Pillwort
Grass-wrack pondweed
Scottish small-reed
Large-fruited prickly-sedge
Cornflower
Young's helleborine
Euphrasia eurycarpa (an eyebright)
Euphrasia heslop-harrisonii (an eyebright)
Euphrasia rhumica (an eyebright)
Euphrasia rotundifolia (an eyebright)
Purple ramping-fumitory
Woolly willow
Marsh saxifrage
Shepherd's-needle
Small-flowered catchfly
Greater water-parsnip
Species with an unpredictable response
Turtle dove
Northern hatchet-shell
Sea fan anemone
Styela gelitinosa (a sea squirt)
Bidessus minutissimus (a water beetle)
Tipula serrulifera (a cranefly)
Lunar yellow underwing moth
Argent and sable moth
Square-spotted clay moth
Sword grass moth
Cladonia peziztformis (a lichen)
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