ANNEX 1

FUTURE CLIMATE SCENARIOS FOR NORTHERN IRELAND

CLIMATE CHANGE SCENARIOS FOR NORTHERN IRELAND

Dr Nick Betts
School of Geography
Queen’s University Belfast
Belfast BT7 1NN

2. FUTURE CHANGES IN NORTHERN IRELAND

Climate change scenarios

Since no single climate change scenario can capture the range of possible climate futures, four generalised climate scenarios for Northern Ireland are presented here: Low, Medium-low, Medium-high and High. These are derived from the UK Climate Impacts Programme (UKCIP) 1998 scenarios (UKCIP, 1998), which are in turn derived from the HadCM2 General Circulation Model (GCM), developed at the UK Meteorological Office Hadley Centre. The four scenarios are being used for all the UK regional climate impact assessment scoping studies, to ensure comparability. The names of the scenarios refer to respective warming rates. Note that these scenarios do not incorporate consideration of sulphate aerosol influences.

Climate changes are presented in these scenarios for three future thirty-year periods centred on the 2020s, the 2050s and the 2080s. The climate change for each of these periods is calculated as the change in thirty-year mean climates with respect to the 1961-90 average. Thus the scenarios for the 2020s are assumed to be representative of the period 2010-2039, the scenarios for the 2050s represent the period 2040-2069, and the scenarios for the 2080s represent 2070-2099.

Changes in carbon dioxide

Atmospheric carbon dioxide concentration for 1961-90 averages 334 ppmv (parts per million by volume). Dependent on the emissions scenario chosen, future estimated carbon dioxide values range between 398 to 447 ppmv in the 2020s, between 443 to 554 ppmv in the 2050s, and between 498 to 697 ppmv in the 2080s.

Temperature

Below are the range of possible changes in temperature (°C) for Northern Ireland, derived from the four UKCIP98 scenarios. These are compared with the 1961-90 mean.

Rainfall

Below are the range of changes in precipitation for Northern Ireland, derived from the four UKCIP98 scenarios. These are expressed as a per cent change from the 1961-90 mean. Note that patterns of precipitation change are less consistent (and hence presumably less reliable) between seasons and scenarios, than is the case for changes in temperature.

Mean seasonal climate

Results from the Medium-high scenario are presented below. This is not necessarily the best-guess estimate, but more modelling results are readily available for this scenario.

WINTER (DJF) sees a small decrease in diurnal temperature range of about 0.2°C by the 2080s. This change is consistent with an increase in cloud cover and precipitation. Vapour pressure increases 1.7 hPa by the 2080s, but, with increasing mean temperatures, relative humidity changes little. Incident short-wave radiation decreases by 1 Wm^-2, a change consistent with increased cloudiness (1%), and precipitation. There is little change in mean wind speed over Northern Ireland by the 2080s. Winter potential evapotranspiration increases by 12%, mostly during the last decades of the century, being particularly sensitive to temperature.

SPRING (MAM) sees a reduction in diurnal temperature range of 0.4°C by the 2080s, which correlates with increased cloud cover (1%). Incident short-wave radiation decreases by 2 Wm^-2. Vapour pressure increases of 1.7 hPa are accompanied by a slight rise in relative humidity (1%). Wind speeds show little change from the present. Potential evapotranspiration in spring increases 5% by the 2080s.

SUMMER (JJA) diurnal temperature range decreases some 0.2°C by the 2080s, in association with slight increased cloud cover (0.5%) and reduced short-wave radiation (2 Wm^-2). Increases are estimated in vapour pressure (2.2 hPa) and relative humidity (0.5%). Mean wind speed increases 1.5 per cent by the 2080s. Potential evapotranspiration shows a 6% increase, which will compound the effect of the summer precipitation decreases (2-3 per cent)on water resources.

AUTUMN (SON) sees an increase in diurnal temperature range of 0.1°C, accompanied by an increase of short-wave radiation (3 Wm^-2 ) and reduced cloud cover (2%). Vapour pressure increases of 2.2 hPa are accompanied by minimal changes in relative humidity. Increased wind speeds of about 4% combined with increases in radiation, means that potential evaporation rises 18% by the 2080s, with an 11% increase as early as the 2020s.

Climate variability and extremes

In terms of year to year variability, winter temperatures become less variable and summer temperatures more variable. Precipitation variability increases in every season.

The number of degree-days for a minimum temperature below 0°C decreases by more than 75% by the 2080s, while the degree-days for a maximum temperature above 25°C more than trebles. Degree-days for mean temperatures above 5.5°C (indicative of the plant growing season) increase by more than 5% per decade.

More frequent days with high summer wind speeds are predicted, but there is little change in winter daily wind extremes (mean wind speed more than 10 metres per second). In winter there exists a possibility that overall gale frequency declines in future, although very severe winter gales increase. Any changes in summer gale frequencies are likely to be modest (~10 per cent increase).

Precipitation intensities increase in both winter and summer, the most intense events becoming several times more frequent than at present. This is likely to lead to greater risk of flooding.

By the 2080s lightning frequency may increase by up to 20 per cent, consistent with the anticipated increases in precipitation intensities.

Related to changing airflow patterns over the whole of the British Isles, for the 2080s period, analysis suggests a tendency for autumns to experience windier conditions, with a reduction in northerly and easterly airflows and an increase in southwesterly and westerly flow. Summers become slightly more anticyclonic in character with more westerly and northwesterly flow, while winter and spring become slightly less cyclonic. (See Figure 9 for a comparison of present-day precipitation  patterns associated with differing airflows.)

It needs to be emphasised that even under the changes in average thirty-year climates, the year-by-year evolution of climate over Northern Ireland will have substantial variability, with periods of opposite trend to those presented here for the expected thirty-year mean changes (see UKCIP, 1998).

It should also be noted that models developed subsequent to the UKCIP98 scenarios (e.g. the HadCM3 GCM), indicate some differences to the UKCIP98 scenarios which have been analysed here, notably with respect to enhanced summer dryness and significant increase in mean wind speed.

Sea-level change

Estimates of the change in mean sea level around Northern Ireland coasts by the 2050s resulting from global climate change range between 13 cm to 74 cm, dependent upon scenario. These values must be modified in relation to natural vertical land movements.

Reference

UK Climate Impacts Programme (1998). Climate Change for the UK: Scientific Report. UK Climate Impacts Programme Technical Report No. 1,  Climatic Research Unit, Norwich. 80 pp. Available from http://www.ukcip.org.uk

ANNEX 2

Preliminary Statement of Potential Impacts of Climate Change in NI

Health Sector

Task Manager – Dr Vivienne Crawford

The health sector could have to deal with a number of problems resulting as a direct or indirect consequence of climate change.  It may also accrue benefits.  For example, milder winters will reduce mortality particularly amongst elderly people.  In contrast however, there may be an increase in certain infectious diseases, which could counterbalance the reduced mortality rates.  Other infectious diseases may decline.  At the least, changes in patterns of spread, time of peaks etc. will occur and may contribute to health effects indirectly. In addition, the potential effects on human health resulting from changes in infectious diseases within the animal food chain must be considered. 

The cardiovascular health of the general population could improve if a warmer climate leads to a change in diet and lifestyle. This potential improvement would result indirectly from diet and lifestyle effects upon cardiovascular risk factors such as fibrinogen, cholesterol, blood pressure and exercise. Conversely, prolonged periods of heat coupled with poorer air quality, particularly in urban areas, would increase the incidence of heart attacks, strokes and respiratory illness, resulting in an increased burden on health services.  Cardiovascular mortality and morbidity exhibit a strong seasonal rhythm, normally with peaks in the coldest part of the annual cycle.  In the proposed warmer climate this seasonality may be either attenuated or exhibit a shift in peak to hotter weather.  There is evidence that this is already occurring in NI. Whether seasonality is lost or the peak is shifted there would clearly be implications for the provision of health services.

Respiratory illnesses such as COPD and asthma in particular, will escalate as a direct result of increases in pollution, temperature and precipitation.  Alternatively, a requirement for less indoor heating using solid fuels may reduce respiratory illness.  This association between indoor heating and asthma has been shown locally.  Hotter weather may lead to an increase in outdoor cooking and to difficulties in keeping appropriate foods cold.  We could therefore see a rise in gastrointestinal illnesses.

Health may be affected in a number of indirect ways by the increase in precipitation.  Similarly there will be both beneficial and detrimental health impacts associated with increased exposure to sunlight.  Sunlight exposure is a possible risk factor for visual disability due to macular degeneration in older adults.  Additionally there may be more skin malignancy while alterations in diet and lifestyle may reduce or increase other forms of cancer.  The potentially longer growing season is likely to increase the population’s exposure to allergens with associated health effects.  There may be beneficial psychological and psychiatric health implications of increased sunshine, for example improved mood, less seasonal affective disorder and mental health issues. 

The indirect impact on health resulting from possible changes in crops and animal species is difficult to assess.  There may be specific niche effects, for example changes in farming practice may change diseases in this population. Increased phytoestrogens in the environment may lead to decreased male fertility.  It is impossible to gauge the impact of the increased threat of severe weather conditions and the potential indirect effects of water quality are also difficult to assess. 

In summary, the potential interaction of beneficial and detrimental health effects of climate change together with the determination of the scale of these effects, offer an important challenge for scientists.  The possibilities for adaptation, to accentuate the benefits and contain the detriments should be our focus.  Reactionary behaviour will be inappropriate and advanced planning is essential.

ANNEX 3

Preliminary Statement of Potential Impacts of Climate Change in NI

Impact of climate change upon water resources in Northern Ireland

Task Manager – Dr Nick Betts

Present situation

From a resource management viewpoint, Northern Ireland is over-endowed with water, with one-third more water being discharged per km² than in England and Wales. Furthermore, a markedly lower population density promotes a correspondingly lower demand for water. Despite this adequacy in terms of the water balance equation, pressures exerted by continued urban expansion and prolonged dry periods create water supply problems in summer.

Water Service supplies 700 million litres of water daily to a Northern Ireland population of 1.7 million.  Management of surface waters is principally concerned with, disposal of excess water from the land, maintenance of river water quality in the face of changing agricultural and industrial technology, and the safeguarding traditionally excellent fish stocks. Land drainage, fertilizer use, and effluent disposal constitute the major management practices affecting quantity and quality of water resources. Groundwater is important to water managers because it determines river flow in times of low rainfall. In turn, low river flows inhibit the ability of a river to dilute effluent and to support fish populations, and river management techniques are thereby directed at ways to maintain or augment these flows. The variety of environmental influences and the rising expectations of the public are reflected in recent marked improvements in both the treatment of water and the monitoring of water quality.

Future changes

It is anticipated that there will be a 20% increase in water consumption over the next 20 years. Climate change in terms of changing patterns of temperature, evaporation and precipitation is of particular concern to the water industry. UKCIP scenarios indicate that future warming in Northern Ireland at all seasons during the 21^st century will be accompanied by increases in potential evapotranspiration of between 5% and 18%, dependent on season. While annual precipitation is expected to increase, seasonal changes may be more pronounced. Winter precipitation is expected to increase by 7% to 22%, in contrast, summer totals are expected to decrease by 2% to 7%. Another significant factor is the possibility of increased precipitation intensities in both winter and summer and enhancement of the flood hazard.

The results of such climate change would reduce availability of surface water in reservoirs and rivers for abstraction in summer. A need exists to reduce domestic demand through behavioural change in patterns of water consumption and the promotion of water metering. Management policy must continue action to reduce leakage from the distribution system. Low river flow levels would also have an adverse impact upon water quality, as would also turbulent flows after heavy rainfall, both scenarios probably requiring enhanced water treatment. Reductions in summer river flows could lead to deterioration in water quality, there being less water to dilute the licensed discharges.

Increased frequency of intense rainfall events might necessitate enhanced capacities of wastewater treatment plants and sewer systems. Needs may also exist to upgrade flood defences, and to review land use development of flood plains.

The consequences of potential climate change during the 21^st century upon water resources and water quality in Northern Ireland appear to be of significance. It is essential that there exists long term commitment from Government, or future private organisations, to regular reviews of best practice in sustaining supplies of the highest quality water throughout the year in Northern Ireland, despite environmental change.

ANNEX 4

Preliminary Statement of Potential Impacts of Climate Change in NI

Implications of climate change for Northern Ireland: Informing Strategy Development

Task Manager – Dr Christopher Tweed

Preliminary analysis of the supplied predictions for climate change in Northern Ireland suggests a range of possible impacts on buildings, both positive and negative. Buildings, of course, also directly change the microclimate of their environs and through the use of distant resources and the generation of waste can have much wider impact on the environment. Table 14.1 summarises the main sets of issues which need to be addressed in the current study.

Table 14.1: predicted climate changes and possible impacts on buildings.

Many of these possible impacts will depend heavily on where buildings are located, on other factors which may work in combination with climate change. For example, increased rainfall may only be an issue where certain ground conditions prevail, such as heavy clay, which will impede natural drainage, or on sloping sites.

Some of the changes may lead to improved conditions in the building sector. The predicted shortening of the heating season is an obvious benefit, although this could be offset by the need for summertime cooling, at least in office and commercial developments. The reduction in solar radiation during winter months decreases the potential for useful solar gain when it is most needed. However, Northern Ireland has limited potential for solar heating in winter and to make significant gains buildings need to be carefully managed to prevent night time longwave radiation losses from exceeding day time solar gains.

The initial impression is that the impact of climate change is likely to be small overall but will vary considerably depending on conditions on individual sites. Two of the biggest problems which currently affect buildings in Northern Ireland are wind driven rain and dampness. Both seem certain to continue, although with higher PET values there may be some reduction in relative humidity, which could alleviate some problems of dampness.

Northern Ireland remains critically dependent on imported materials and energy. If there are prolonged disruptions to the supply of either it will have a profound effect on buildings. Energy prices are certain to continue rising, and so there is little cheer in the reductions of the heating season suggested by the climate change predictions. Reliance on imported energy will ensure that the NI economy will continue to be at the mercy of energy prices set by others.

ANNEX 5

Preliminary Statement of Potential Impacts of Climate Change in NI

Implications of projected climate change for the Northern Ireland coastal zone

Task Manager – Professor Julian Orford

There are three principal natural forcing factors of coastal change related to projected climate change over the next 50 years

• Change in eustatic sea level, i.e. change in the total volume of water in the oceans causing a secular and persistent rise in the average mean sea level position (MSL).
• Changes in storminess i.e. changes in the short term (up to days) rise of MSL
• Changes in terrestrially derived sediment supply to the coast

Changes in eustatic SL are driven principally by two climatically induced factors: the expansion of sea water volume due to increased exchange of atmospheric heat to the upper oceans, and an increase in sea water volume due to a persistent negative budget in continental ice, i.e. melting of land ice. Expansion of ocean water due to atmospheric-ocean exchange of heat (the steric effect) is thought to account for approximately half of the contemporary estimates of future MSL rise. The latest IPCC (2001) estimates follow that of Houghton et al (1995) identifying a '"business as usual" scenario of c 49cm of SL rise over the next half century. Such global eustatic estimates are constrained by the local effects of crustal change (isostatic and tectonic) which may accelerate or decelerate MSL changes. The combined eustatic and isostatic movement is recognised as the relative sea-level change (RSL).

Although contemporary annual RSL change rate varies from c +1.5-2mm a^-1 to +0.5-1mm a^-1, on a south to north UK gradient (Woodworth et al., 1999) there is no consistent estimate for Northern Ireland. Carter (1982) identified falling RSL trends of <2.5mm a^-1, over the 20^th-century for Malin Head and Belfast Harbour, which he thought were due to a strong isostatic remnant signal from ice unloading post the last glacial maximum. Carter further identified the possible effects of 20^th-Century Belfast harbour expansion affecting the declining RSL signal he obtained for that site. Orford (2000) identified the key problems in estimating an overall NI RSL change rate given the breaks in, and non-overlapping nature of tide-gauge data from the four data generating sites available in the north of Ireland. A further key problem was the need to detrend nodal tidal (18.6 years periodicity) signals from data series, which had not been undertaken by Carter. New analysis of detrended data from Malin Head (1958-1995) and Belfast (1918-63) indicated a RSL of near zero value, but superimposed upon low amplitude decade-scale oscillation in RSL. These oscillations have major implications for estimates of RSL dependent on data window length, and are thought to have affected Carter's 1982 analysis. Analysis of recent (but not detrended) MSL data from Portrush and Bangor tide gauges (1996-200) both identify positive trends in RSL of <+2.5mm a^-1. It is still uncertain whether these recent up-swings reflect eustatic acceleration of RSL, or are part of the nodal tidal expansion, or relate to an upswing in the decade-scale oscillations running through NI data.  Regardless of the origin of the upswing, there may be contemporary problems ensuing from this RSL rise in the present decade, regardless of any accelerations over the next 20-50 years.  Such accelerations are likely to translate into an annual average RSLR of c.2 times the current extremes.

Changes in storminess are likely to be characterised by changes in annual atmospheric depression number, depression intensity and depression approach vectors. Storms and especially extreme storms (i.e. Boxing Day storm of 1998 with mean ground wind velocities of up to 50m s-1) identify a wide ranging potential for change in short term rises in MSL due to surge and extreme wave generation. There is also the direct effect on coastal structures from such forces. It is important to recognise that there are two coastal NI provinces (north and east coasts) which may suffer differentially the affects of accelerated climate induced change. Although storm modelling (ECHAMP2) using a doubling of CO₂ for the eastern Atlantic off Ireland, indicates a slight reduction in depression number, there is a rise in intensity i.e. deeper depressions (Devoy and Lozano 2000) moving over the Irish Atlantic coast. Future increased equatorial warming may have a major effect on hurricane incidence in the North Atlantic, outside of their generating area. The influence of ex-hurricanes moving as deep depressions across Ireland from a southerly direction has been somewhat neglected but should not be forgotten in the future storm scenario analysis (Cooper and Orford 1998). The role of extreme storms on coastal configuration needs also to be reconsidered (Orford et al 1999), as do all storm tracks, as orientation changes will have significant impact on the coast, although storm track modelling is still a relative unknown. Changes in Atlantic offshore significant wave height over the latter part of the 20^th-Century are thought to be within a natural variance (Von Storch et al., 1993) despite earlier concerns that the North Atlantic was "roughening" (Draper and Carter, 1988). Modelling the hazard of increasing storm wave heights in the Irish Sea identifies differential vulnerability between the Antrim and Down coasts (McFadden 2001). We have little knowledge of future storm changes in the Irish Sea as opposed to model results for the eastern Atlantic that might affect the north coast of NI. Of some concern is the increased incidence in southeastern Irish Sea storms as a consequence of a rise in potential azonal high pressure blocking conditions to the east and southeast of the UK. A few degrees change in storm approach direction could have major impacts on the south Down coast, while any increase in coastal wave energy will be observed via a reduction in beach gradients.

Sediment supply to the coast comes from terrestrially derived sediment carried via rivers and terrestrial basement material eroded at the shoreline. The former has not been a major influence in NI coastline over historical times. The issue of increased fluvial transport and hence increased sediment load from catchments is not likely to be significantly changed, unless land-use practices materially alter so that more bare soil is exposed to increased precipitation. Urban catchments may experience greater runoff and as a consequence, deposition in tidal estuaries particularly Belfast (Orford et al, 1997) and Derry may be differentially affected. There are no current studies of this issue. Coastal erosion as a means of supplying sediment to the beach is important for NI. Its importance has been gauged by estimates of source, transport and sink units making up coastal cells for parts of the NI coastline (Bowden and Orford 1984), however no numerical estimates of changes in this volume due to future climate change have been undertaken for NI.

Potential changes

A change in MSL is per se not an indicator of major coastal change, however MSL acts as the datum for wave and tide activity that are the causes of coastal change.  The geomorphology of the coast is an expression of mitigation of forcing energy expenditure. Change the point of energy application and the configuration will change. Lifting the point of application through a MSL change means that the coastal configuration will also change; though the rates of change are often out of step, such lags making predictions of coastal change very uncertain. These changes will be accelerated by any increase in wave energy or surge level that are associated with atmospheric changes.

A rise in RSLR will lead to both increased inundation of low coasts and erosion of soft coasts even before consideration of further increases in wave activity. The intertidal zone will be squeezed where the landward limit is constrained by a built-response. The loss of intertidal areas of open coasts, by coastal squeeze and increases in wave energy will be seen in the stripping of sediment volume from, and a general coarsening of sediment sizes on beaches. The loss of intertidal zones in closed and estuary coasts will see a diminishment in protected habitats and a loss of marsh with its associated loss of bio-diversity. It is likely that dunes coasts will suffer non-sustainable beach and front-of-dune erosion. Soft and non-indurate cliff (glacial) coasts (Co Down) are likely to retreat with rates increasing >1m a^-1. Hard rock coasts are unlikely to show any great change, though where hard rock has been a substantial foundation to soft glacigenic sediment perched above contemporary MSL (the Ards Peninsula), there may be major retreat of the glacigenic element.

References

Bowden, R. and Orford,J.D. 1984 Residual sediment cells on the morphologically irregular coastline of the Ards Peninsula, Co. Down. Proc.Royal Irish Acad., 84B: 13-27.

Carter, R.W.G. 1982 Recent variations in sea level on the north and east coasts of Ireland and associated shoreline response. Proc. Royal Irish Acad, 82B: 177-187.

Houghton, J.T., Meira Filho, L.G., Callander, B.A., Harris, N., Kattenberg, A. and Maskell, K., (eds.), 1996. Climate Change 1995: The science of climate change. Cambridge University Press, Cambridge, 572 pp.

Cooper, J.A.G. & Orford, J.D. 1998  Hurricanes as agents of mesoscale coastal change in western Britain and Ireland. . J.Coast. Res. SI 26 ii: 123-128.

Devoy and Lozano 2000 Storminess and environmentally sensitive Atlantic coastal areas of the European Union. Final Report for the Commission of the European Communities, Contract ENV4-CT97 0488.

McFadden,L. 2001 Unpublished Ph.D. Thesis, Queen's University of Belfast.

Orford, J.D. 2000 Tide Gauge determinations of 20^th-Century RelativeSea-Level Changes around North-East Ireland. Unpublished Report for Environment and Heritage Service, Northern Ireland 10pp.

Orford, J.D., Cooper, J.A.G., Jackson, D., Malvarez, G. and White, D. 1999 Extreme storms and thresholds on foredune stripping at Inch Spit, south-west Ireland. Coastal Sediments ’99, Amer. Soc. Civ. Engr.: v.3: 1852-1866.

Orford, J.D., Cooper, J.A.G. and Smith, B.J. 1997 LOICZ: The human factor as an influence on the Irish coast. In Sweeney, J. (ed.) Ireland and Global Change. Royal Irish Academy, Dublin: 88-107.

Von Storch, H., Guddal, J., Iden, K.A., Jonsson, T., Perlwitz, J., Reistad, M., de Ronde, J., Schmidt, H. & Zorita, E. 1993 Changing statistics of storms in the North Atlantic, Max-Planck Institute Met. Report 116, Hamburg 19pp.

Woodworth, P.L., Tsimplis, M.N., Flather, R.A. & Shennan, I. 1999 A review of the trends observed in British Isles mean sea level data measured by tide gauges. Geophys. J. Int., 136: 651-670.

ANNEX 6

Preliminary Statement of Potential Impacts of Climate Change in NI

Implications of projected climate change for Biodiversity in Northern Ireland

Task Manager – Professor Ian Montgomery

The most important climatic changes suggested by the model likely to impact on animals and plants, and the functioning of ecosystems involving microbiological processes, are: increased mean temperature and, in particular, the rise in the number of degree days in excess of 25^oC and fall in number of degree days below 0^oC; the rise in overall precipitation; the rise in evapotranspiration in winter and autumn; and, the increase in number of storms effecting major catastrophic events.  Plant distribution and abundance is likely to be greatly affected by temperature, water availability and evapotranspiration all of which have a direct effect on photosynthesis.  Animal mortality is likely to be impacted by milder but damper winters while catastrophic events effect great change in whole communities, for example, due to loss of woodland or flushing of water courses.  Microbiological processes will be accelerated by higher temperatures.

The marine environment of NI is very diverse with extensive sheltered and exposed hard and soft sediment shores.  Rise in sea level will impact on the distribution of organisms in the intertidal.  Rapid sediment movements may produce temporary discontinuities in some populations, such as eel grasses and algae, but in time there should be recolonisation although it is unlikely that there would be a return to former distributions or status.  Higher energy littoral environments associated with storms in addition to sea level rise might change vulnerable soft sediments substantially, potentially affecting their value to wintering wildfowl and waders.  Higher coastal sea temperatures could lead to a gradual northward spread of southern species and loss of more northern species.  Hence, the coastal marine fauna may become increasingly like that of more southerly coasts in the British Isles.  The combination of higher energy and temperature in the marine environment might remove a number of soft sediment types that are the product of a unique combination of sediment, aspect, tidal range and latitude.  Highly valued sites such as The Dorn or even Strangford Lough in general, may be subject to change reducing their uniqueness.  At sea, relocation of fish in response to changed surface temperatures particularly during the spring and summer, may affect the energetics of seabirds nesting on coastal sites.

The freshwaters of NI are particularly abundant.  However, they are largely degraded by eutrophication and introduction of alien species.  Eutrophication will be promoted by higher temperature but greater rainfall will increase flow.  Reduction in nutrient input is planned so the major affect of climate change may be a direct effect of temperature and increased run off.  These may change distributions of plants locally and it is possible that losses of species from catchments will not be balanced by invasions due to low dispersal rates in water plants.  Higher summer temperatures could lead more easily to deoxygenation and hence it is important that planned reductions in nutrient inputs are realised.  There are few pristine lakes remaining but these should be regarded as vulnerable to increasing temperature due to the higher incidence of degree days in excess of 25^oC.  The major effect on rivers is likely to come from sudden rainstorms.  These have the potential to erode river banks especially those lacking significant vegetation as in many NI rivers.  Microbiological processes of lakes and diverse taxa such as aquatic bugs and beetles are temperature sensitive such that there should be a gradual change towards a warmer water biota.  Higher rainfall could result in enhanced groundwater movement creating, for example, more freshwater flushes.  These are associated with, for example, a specialist insect fauna.  These rarities might become more common.

The terrestrial habitats of NI vary from fens to deciduous woodland and unimproved lowland wet grassland to sand dunes.  The greater area in both upland and lowlands, however, is under pastoral agriculture.  These cannot be ignored in considering how climate change might impact on biodiversity.  Agriculture in NI is likely to continue to be chiefly pastoral although higher summer temperatures and increased degree days over 25^oC may promote cereals and other arable crops.  The latter may have a positive influence on, for example, cereal feeding birds that have declined in number in recent years.  Warmer summers combined with more extensive agriculture might also go some way to reversing the decline of hay as wintering forage.  This potentially would have a positive effect directly on grassland flora, ground nesting birds and Irish hare.  The major effect on terrestrial biotas, however, will be a longer growing season.  There are already data suggesting that breeding seasons start earlier.  Where this is associated with occasional inclement weather after breeding has commenced there could be negative effects on plants, insects and birds effected by sudden frosts or high rainfall.  The asynchrony of budburst and emergence of insects from overwintering eggs could have severe effects on nesting woodland birds in some years.  Severe storms have a positive effect in creating opportunities in woodland for young trees.  Increased disturbance of a more frequent and radical nature could lead to a more homogeneous species and age structure of trees and ultimately reduced opportunity for associated species.  Species like the introduced Sycamore are more likely to flourish than natives such as Oak.

ANNEX 7

Preliminary Statement of Potential Impacts of Climate Change in NI

Geomorphological and Hydrological changes

Task Manager – Professor Brian Whalley / Dr David Favis-Mortlock

In general, the effects will be responses to the predicted increase in overall precipitation but especially in winter precipitation.  Additionally, as there are predicted increases in variability and especially in the intensity of precipitation events, all of the processes listed below are likely to see increased activity.

River basins

Climate change is expected to produce a variety of effects within river basins with respect to hydrology and the land use in any basin.  There may also be a secondary effect such that changes in land use (whether or not the result of climate change) will affect the hydrology.  These secondary factors may have response times which vary from a few years to tends of years.  Evapotranspiration changes will produce effects on the vegetation cover which need to be reviewed as part of the influence of secondary basin factors concerned with land use. 

Stakeholders need to be aware of a number of, often interrelated, factors associated with climate change.  Recent, highly publicised, events have probably helped to increased awareness of problems in floodplains.

Flooding.

Rivers flood naturally.  The flood plain is a consequence of this natural process over thousands of years.  Where there has been human construction on the flatland of the floodplain there has usually been a response  to control the river to stop it meandering and to keep the river within the confines of a canalised section to prevent the natural flooding.  However, if a river does overtop (or break through) its lateral defences then the consequences may be severe.  In the last few years there have been several instances of sever flooding to homes and commercial properties and these have often been attributed to 'global warming'.  Most notably, the large river catchments in Kent, Sussex, Yorkshire and Devonshire in the October-November period of 2000 show the dangers of building on floodplains or close to canalised sections of river, even when the dwellings etc have been there for many, perhaps hundreds of years. Unfortunately, even when there have been records of river levels/discharges over decades, it is not possible to predict what the frequency of 'anomalous' meteorological events will be.  The future scenarios for rivers must ensure that current ('adjustment') methods for floodplain management are used.  This entails the concept of the 'floodway' (1 flooding event every five years) and a series of zoned areas on the floodplain.  These zones have predicted flood events corresponding to different levels of economic activity and planning control.  A second method, of minimisation of damage is 'control' but is probably not to be recommended as this is both expensive and unlikely to be of value in the Province.  Flood abatement strategies can, however, be employed.  These rely on land use activity, e.g. afforestation upstream to minimise rapid runoff, are possible but again must be used with careful planning controls. 

Flooding of rivers in coastal areas present a particular problem and which must be related to both sea level rise and coastal deference measures.  The floods at Towyn (N. Wales) well illustrate the problems of unconstrained holiday development in an area subject to spring tidal events  and storms as well as river flooding.

Land use

Constraints may need to be applied to future development in basins associated with flooding.  The hazard zonation schemes (supra) will need to be applied.  New building styles (e.g. stilts) can minimise flood damage but health hazards from sewerage are additional and significant hazards.  Any changes of vegetation in drainage basins, either human induced or natural will need to be evaluated with care.  Not only may vegetation changes affect flooding but may also induce high runoff rates.

Slopes and slope failure

Certain slopes in the Province have a long history of failure after high intensity rainfall.  These will undoubtedly be affected by the predicted changes in rainfall intensity and variability.  In the main, the active failures are in the east of the Province, namely, bog bursts, which are high magnitude but low frequency.  These may be difficult to predict.  The east Antrim coast has long been known for small mud flowslides.  These can occasionally block the road.  Again, prediction long term is difficult.  Long term monitoring suggests that the activity in the period 1985-200 was rather lower than 1970-1985.  As well as occasional high intensity storms which trigger events (which may or may not be sufficiently large as to endanger life or block the road) the antecedent moisture conditions in the slopes also have an effect.  However, even monitoring slopes is not easy so that precautionary measured need to be undertaken.

Other areas which may occasionally produce enhanced slope failure are rock slopes.  There are specific locations where these are  potentially dangerous at tourist sites (Giant's Causeway Coastline, Garron Point) where heavy rainfall, especially preceded by prolonged rainfall, could increase the incidence of rockfalls of varying sizes of block.  As most slope failure events respond rapidly to high intensity precipitation events and the prediction of these is difficult, the next 80 years must be viewed with the assumption of additional hazards to certain areas in general and selected sites in particular.