Climate Change The Risks for Property in the UK

Transcription

1 Climate Change The Risks for Property in the UK UCL Environment Institute Commissioned by

2 Climate Change The Risks for Property in the UK Authors Patrick Austin Yvonne Rydin Mark Maslin 1

3 Foreword It is now a commonly accepted and often repeated fact that climate change is the greatest challenge the world currently faces. It is also generally accepted that whilst we must clearly do all we can to lower emissions and control temperature change, we must also accept the reality that change is now inevitable. In the real estate sector the sustainability agenda has principally focussed on the environmental performance of individual properties, as the introduction of initiatives such as Energy Performance Certificates and the forthcoming Climate Change Bill have centred on the reduction of carbon dioxide emissions and energy consumption. As a result of this focus on climate change mitigation, relatively little is currently understood about the likely impacts of climate change upon UK real estate. For our industry the key questions now are how climate change will impact, where in the UK will its effects be most strongly felt and how do we need to adapt both now and in the future to minimise these impacts? We know we can expect warmer, wetter winters; hotter, drier summers and more frequent extreme weather conditions most obviously flooding and droughts. These impacts will also vary regionally and will lead to localised pressures on infrastructure. In commissioning this report, we felt there was a fundamental gap in the UK real estate sector s knowledge about what these potential impacts might be and what they would mean for real estate holdings in different parts of the country. This information is critical if we are to meaningfully debate the best course of action over the coming years. The findings we have uncovered pose many demanding questions and whilst we cannot yet claim to have any definitive answers, this information is as a first step in gaining a clearer understanding of the risks we are facing and the practical steps we might take to adapt to them. It is a sobering thought that the authors of the report have advised us that the risks posed by climate change may have been underestimated by the IPCC, with the 2

4 possibility that changes may well be more severe or occur earlier than anticipated. There is a challenge here for us all to consider this report is a beginning, but how should the sector monitor any changes in the conditions that have been forecast and any indicators that will give us early warning that the worst case scenarios are becoming more rather than less likely? One of the key commitments we at Hermes Real Estate made when we published our Responsible Property Investment Challenges in 2006 was to encourage a debate to raise awareness and to respond to the huge challenges we are facing as an industry and as a society. There is both a moral imperative and an increasingly compelling fiduciary incentive for us all to engage in this discussion but the time for debating generalities and first principles is at an end. None of us are able to predict the future with absolute certainty but what is clear is that the challenges posed by climate change are not going to disappear. What is crucial is that we begin to formulate a plan of action and look at how our industry can address these challenges. Alongside our commitments to cut our emissions and our waste, we must establish and fully analyse the risks we are facing as an industry only then can we have an effective debate about the measures we must take to mitigate those risks. We are committed to refining our analysis and would welcome the opportunity to discuss these findings with anyone interested in this area. If you would like to contribute to this discussion, please contact me at (k.bugden@hermes.co.uk) or Sarah Ratcliffe of Upstream (sarah@upstreamstrategies.co.uk). Keith Bugden Director - Development, Hermes Real Estate 3

5 Contents Executive Summary page 6 1 Climate Change in the UK page Introduction page Observed 20 th century global climate change page Projections of future changes in global climate page Is the IPCC to conservative? Page Observed climate change in the UK page Temperatures page Rainfall page Climate change scenarios for the UK page Sources of uncertainty and level of confidence in UK climate projections page Temperatures page Summer temperature page Winter temperature page Rainfall page Summer Rainfall page Winter Rainfall page Soil moisture page Summer soil moisture page Winter wind speeds page Seasonality and inter-annual variability page The North Atlantic Oscillation and storm events page Sea level rise page Summary page 44 2 Vulnerability of UK Property to Climate Change page Vulnerability and climate change impacts page Vulnerability of property to changes in temperature page Vulnerability of property to changes in rainfall page Vulnerability of property to changes in soil moisture page Vulnerability of property to changes in wind speed page Climate change risks and UK property types page Residential property page Office and business parks page Industrial premises page 57 4

6 2.2.4 Warehouses and distribution page Retail premises page Climate change risks and infrastructure systems page Transport infrastructure page Energy supply infrastructure page Water supply infrastructure page Sewerage infrastructure page Urban drainage infrastructure page The role of property insurance page 65 3 Climate change scenarios for selected UK cities page Headline messages page Temperature page Precipitation page Soil moisture page Winter wind speed page 76 4 City by city scenarios page London page Belfast page Birmingham page Bristol page Cambridge page Cardiff page Edinburgh page Glasgow page Leeds page Liverpool page Manchester page Newcastle page Southampton page Thames Gateway page What should the property sector do next? page Acknowledgements page References page 136 5

7 Executive Summary The UCL Environment Institute has analysed the physical impact of anticipated climate change on UK property during the 21 st century. This report focuses on adaptation rather than mitigation and provides a summary of the existing scientific knowledge on climate change impacts as they will affect the UK and an assessment of the vulnerability of the property sector so that it may adapt to these changes. How is the global climate changing? Climate change is a proven reality and is already having an impact. Eleven of the years between 1995 and 2006 rank among the twelve hottest years globally since records began in The Intergovernmental Panel on Climate Change (IPCC) estimates that by the end of the 21 st century, global average temperatures could rise by 1.1 o C to 6.4 o C, and some consider that even these estimates are conservative. Rising temperatures have led to an increase in global sea levels by around 17 cm in the 20 th century. IPCC estimates that by the end of the 21 st century, sea levels may rise by cm. But there have been studies suggesting the rise will be in the order of 1.4 metres. What does this mean for the UK climate? Since 1961 annual average temperatures across the UK have risen by between 1 o C and 1.7 o C depending on region. Nine of the ten warmest UK years on record have occurred since Summer rainfall has declined by up to 17% since 1961, while winter rainfall has increased in all parts of the UK. The United Kingdom Climate Impacts Programme (UKCIP) indicates that throughout the 21 st century, the UK will be subject to progressively: Warmer and wetter winters Hotter and drier summers More extreme rainfall events Sea level rise Reduction in soil moisture, especially during the summers Increased wind speeds and atmospheric depressions. 6

8 What will be the impact on UK property? This pattern of climate will impact on UK property in a number of ways: Occupiers of buildings will be more prone to heat stress during the more frequent heat waves. This could potentially disrupt activities in high street shops, offices, warehousing and industry, as well as affecting the well-being of households. There will be an increased risk of flooding in locations vulnerable to rivers bursting their banks. But in urban locations there will also be increased exposure to the risk of flash flooding, as the run-off from hard surfaces overwhelms the capacity of urban drainage systems. Water shortages will affect areas with less rainfall, affecting occupiers through water constraints and increased costs. And Ground movement will threaten the stability of buildings in areas where properties are located on clay soils and the standards of construction, particularly with regard to foundations, prove inadequate. UK Infrastructure will be affected too. The infrastructure systems that underpin all urban activities will also be affected. Transport, energy supply, water supply, sewerage and urban drainage systems will all struggle to cope with heat waves, higher wind speeds, increased rainfall and consequent flooding. Investment will be required to ensure that property occupiers are not affected by severe and costly disruptions to these essential services. Which areas will be most affected? Using the UKCIP scenarios, the UCL Environment Institute analysis shows that the southern parts of the UK will be most affected by climate change. Using data at the scale of 50 km grid squares, the analysis suggests that the city of Southampton is particularly likely to be adversely affected. However, other cities such 7

9 as London, Bristol, Cardiff and Cambridge are also predicted to suffer negative impacts. Locations in the north of the country, such as Belfast, Edinburgh, Glasgow and Newcastle will not be affected to the same extent by climate change. However, every location in the UK will need to prepare for a significantly altered climate by the end of the 21 st century. What should the UK property sector do next? There is an urgent need for the property sector to set in place means for being regularly updated on the impacts of future climate change. The scientific evidence in this area is continually evolving. The costs of not being informed and the failure to adapt to climate change are substantial if the sector relies on out-dated analyses. The UCL Environment Institute analysis has shown that different parts of the UK will feel the impacts of climate change very differently. The UK property sector needs to understand this in more depth. The UKCIP scenarios do not take account of features such as the urban heat island, which will make temperature increases more severe, or local flood protection schemes, which seek to protect areas from the effects of heavy rainfall. The UK property sector needs research at a more finely-grained level that will highlight the impacts of climate change in specific localities, taking all local features into account. 8

10 1 Climate Change in the UK 1.1 Introduction Climate change is hardly a new phenomenon, over the last 2.5 million years the Earth has been subjected to a series of glacial stages, or ice ages, and subsequent warm periods, or interglacial stages. These substantial shifts are driven by changes in the Earth s orbit and axis and in some parts of the world temperatures may have fluctuated by more than 15 C (Lowe and Walker, 1997). As we enter the 21 st century, the Earth s climate is changing once more, and rather than natural climatic variability, the overwhelming scientific consensus is that these changes are being driven largely by human activity, notably the burning of fossil fuels since the beginning of the Industrial Era in the 19 th century and the subsequent release of carbon dioxide (CO 2 ) and other greenhouse gases (GHGs) into the atmosphere (IPCC, 2007a). Even if GHG emissions were to stabilise overnight, past and present emissions will be responsible for much of the global warming expected to occur during the first half of the 21 st century. Such stabilisation is extremely unlikely to happen consequently we must be prepared for changes which are considered by many as one of the greatest challenges facing societies over the upcoming decades. In an attempt to investigate just how the anticipated warming would influence the global economy, Sir Nicholas Stern was commissioned by the UK Government to investigate the economics of climate change. The resulting Stern Report indicated that the world economy may suffer by as much as 5-20% due to a combination of droughts, flooding, water shortages and other extreme weather events arising from climate change (Stern, 2006). In terms of property, the anticipated effects of climate change will affect the obsolescence rates and running costs of even the most recently developed properties, and change the spatial patterns of demand for property, both commercial and residential, across the UK. Consequently it is vital that decisions concerning investments in property are made with an understanding of how climate change may affect the UK, where these impacts will be most keenly felt and just what might be done in terms of adapting to these changes. 9

11 1.2 Observed 20 th century global climate change The availability of large amounts of new and more comprehensive data, the increased sophistication with which it is analysed and the enhanced predictive ability of climate models has allowed The IPCC Fourth Assessment Report (AR4), the final stage of which was released in November, 2007, to build on the earlier work contained in the Third Assessment Report, or TAR (IPCC, 2001). This is apparent in both our understanding of recent climate change and future projections. It is now recognised that since records began in 1850, global average temperatures have increased by 0.76 C (figure 1.1) with 11 of the past 12 years ( ) ranking among the warmest 12 years recorded (IPCC, 2007a). This contrasts with a temperature increase of 0.6 C indicated in the TAR. AR4 states that it is very likely (i.e. that there is at least a 90% chance of being correct) that the warming trend exhibited since the mid 20 th century is due to the anthropogenic burning of fossil fuels with land-use change making a smaller but significant contribution. This compares with the earlier TAR indication that the warming trend was likely (i.e. at least a 60% chance of being correct) to have been a result of anthropogenic activity (IPCC, 2001). This activity has resulted in increased atmospheric GHG concentrations, in particular that of CO 2, the annual growth rate of which was larger during the period (1.9 ppm/year) than it has been since the beginning of continuous direct atmospheric measurements ( average: 1.4 ppm/year); consequently the atmospheric levels of this gas (379 ppm in 2005, compared with pre-industrial levels of around 280 ppm) are higher now than at anytime over at least the last 650,000 years (IPCC, 2007a). 10

12 Figure 1.1. Global surface temperature anomalies ( ) from the average (source: A product of the current warming trend is a rise in sea levels due to the thermal expansion of water and to a lesser extent the melting of land-based ice. From global average sea level rose at an average rate of 1.8mm/year and was fastest over (3.1mm/year). During the 20 th century, sea level is estimated to have risen by around 17cm. However, changes are not simply restricted to temperature and sea level; North and South America have been subjected to increased levels of precipitation, as have northern Europe and northern and central Asia. The frequency of heavy precipitation events has similarly increased over most land areas. Intense and longer drought episodes have also occurred over wide areas (particularly the tropics and sub tropics) since the 1970s (table 1.1) and mid-latitude westerly winds have strengthened in both hemispheres as have tropical cyclones in the North Atlantic. 1.3 Projections of future changes in global climate Even if radiative forcing (the measure of influence that a factor has in altering the balance between radiation coming into the atmosphere and radiation going out, of which anthropogenic CO 2 emissions are the largest component), is maintained at year 2000 levels, a warming trend over the next two decades of around 0.1ºC per decade would be expected, thus we are already committed to a period of warming due to past GHG emissions. 11

13 Figure 1.2. Solid lines are multi-model global averages of surface warming (relative to ) for the scenarios A2, A1B and B1, shown as continuations of the 20th century simulations. The grey bars at right indicate the best estimate (solid line within each bar) and the likely range assessed for the six SRES marker scenarios (source: IPCC, 2007a) In predicting future climate variability, the IPCC uses a range of scenarios (SRES scenarios) all of which are considered equally likely. These are derived from four storylines each describing a future possible state of the world based on demographic, economic and technological driving forces of GHG emissions during the 21 st century. Estimates in AR4 indicate that if CO 2 emissions fall within the range of these scenarios, twice as much warming (0.2ºC) over the next two decades would be expected and that by the end of the 21 st century temperatures may have risen above the baseline value 1 by between 1.1 C and 6.4 C depending upon emissions scenario (figure 1.2) (these values are broadly consistent with those in the TAR and provide the likely range of temperature rise, the best estimate is for a rise of between 1.8 C and 4 C). AR4 also indicates that it is likely that past and future anthropogenic carbon emissions will add to sea-level rise for the next millennium due to the length of time required for the removal of CO 2 from the atmosphere. By the end of the 21 st century, global sea level may have risen between 18 and 59cm depending on emissions (IPCC, 1 The baseline figure is the average value for climatic variables for a particular period, in this case

14 2007a). This is less than the 88cm rise reported in the TAR but unlike the TAR figure, does not include ice dynamic uncertainty for the Greenland ice sheet and as such is not an indication that the risk from rising sea levels is receding. The TAR indicated that by the second half of the 21 st century increased precipitation would be likely (> 66% chance) over northern mid to high latitudes. In AR4 it is stated that increased precipitation at high latitudes is very likely (> 90% chance). Reduced precipitation however, is likely in most subtropical land. Other projected changes relating to extreme events are outlined in table 1.1. Table 1.1 Recent trends, assessment of human influence on the trend and projections for extreme weather events for which there is an observed late 20 th century trend (source: IPCC, 2007a). Phenomenon and direction of trend Warmer and fewer cold days and nights over most land areas Warmer and more frequent hot days and nights over most land areas Warm spells/heat waves. Frequency increases over most land areas Heavy precipitation events. Frequency (or proportion of total rainfall from heavy falls) increases over most areas Areas affected by droughts increase Intense tropical cyclone activity increases Increased incidence of extreme high sea level (tsunamis excluded) Likelihood of occurrence in late 20 th century Likelihood of human contribution Likelihood of future trends based on projections for 21 st century using SRES scenarios Very likely* Likely Virtually certain Very likely Likely Virtually certain Likely More likely than not (nights) Very likely Likely More likely than not Very likely Likely in many regions since 1970s Likely in some regions since 1970 More likely than not More likely than not Likely Likely Likely More likely than not Likely *Virtually certain > 99% probability of occurrence; Extremely likely > 95%, Very likely > 90%, Likely > 66%, More likely than not > 50% Is the IPCC too conservative? The views of those who refuse to accept that human activity has played a central role in climate change have received much attention in the media, if not the scientific literature. The opposite can be said to be true for those who consider the IPCC to be too conservative. The IPCC AR4 report was compiled by 450 lead authors, 800 other contributors, and around 2500 reviewers from over 130 countries. The sheer scale of 13

15 this enterprise has lead to concerns within the scientific community that its key conclusions understate the severity of climate change with earlier volumes of the report being diluted during the lengthy review process. Furthermore AR4 only uses material published up to mid-2006, consequently many new and important findings are not included. For example, Rahmstorf et al., (2007) anticipate that by 2100 global sea-level rise may be as much as 1.4 m, as opposed to the potential rise of 59 cm in AR4. While Shukla et al., (2007) predict that warming in the 21 st century will be closer to the highest projected estimates in AR4. There is also evidence that some changes are occurring quicker than expected. Observational records indicate that the extent of Arctic sea ice has declined considerably quicker than IPCC projections (Stroeve et al., 2007), and may in fact be 30 years ahead of what current climate models are indicating ( Furthermore the IPCC sea-level projections in AR4 are based on little or no contribution from the Greenland and Antarctic ice sheets despite the fact that they have been melting at an accelerated rate (Chen et al, 2006; Velicogna and Wahr, 2006). Hansen et al., (2007) have suggested that if CO 2 emissions continue to rise unabated, these ice sheets may begin to disintegrate in a non-linear fashion and the eventual sea level rise over a matter of centuries, (although they do not rule out decades once wide-scale surface melt is underway), may be around 25 +/- 10m, similar to that 3.5 million years ago, when global temperature was around 2-3 C higher than the present day. There is then a real possibility that the risks posed by climate change, rather than having been exaggerated, as some would like to believe, may have been underestimated by the IPCC with the possibility that changes may be more severe or occur earlier than anticipated. 14

16 1.4 Observed climate change in the UK Climate varies from region to region across the globe. Factors important in these differences include: the uneven distribution of solar heating with latitude; the individual responses of the oceans, atmosphere and land surface, the interactions between these and the physical characteristics of particular regions (e.g. topography). Consequently former and projected changes will similarly vary and this is well illustrated in the projections of rainfall values for Scotland throughout the 21 st century (section 1.5.3). The effects of climate change are already being felt in the United Kingdom most notably in the form of increased temperature and more marked variations in rainfall. In order to prepare for the challenges that lay ahead the United Kingdom Climate Impacts Programme (UKCIP) was established. UKCIP s main aim objective is the establishment of climate change scenarios in order to provide a common starting point for assessing climate change vulnerability, impacts and adaptation in the UK, commonly known as UKCIP02, this will be superseded by a further set of scenarios (UKCIP08) later in The end of 2007 saw the publication by UKCIP of The climate of the United Kingdom and recent trends (Jenkins et al., 2007). This is the first contribution to UKCIP08 and provides a historical context for the future climate change projections. These have been determined for 14 regions across the UK, the 12 UK administrative regions, with Scotland being divided into three on the basis of Met Office climatological regions Temperatures Mean annual temperatures for the UK during the period are shown in figure 1.3. From daily mean annual temperature increases ranged from 1 C in North Scotland to 1.7 C in London (Jenkins et al., 2007). Furthermore, the Central England Temperature record, the longest continuous temperature record in existence, extending back to 1659, indicates that 9 of the 10 warmest years have occurred since 1990, with 2006 and 2007 the warmest and second warmest years respectively. Records also show that from daily mean summer temperatures had increased by 1.2 C in North Scotland and 1.9 C in London (Jenkins et al., 2007). Consequently the number of days with temperatures exceeding 23 C (the threshold temperature for an extremely warm day) has increased, and in August

17 temperatures reached in excess of 100 F (38.5 C) for the first time since records began. The average duration of summer heat waves (defined as more than 5 days in a row which experience temperatures of more than 3 C above the average) has similarly increased in all regions of the UK by between 4 and 16 days. Since 1961 the daily mean winter temperature increase ranges from 1.2 C in North Scotland to 2 C in London, the South East, the East of England, and the East Midlands Temperature Year Figure 1.3. Mean annual UK temperature ( ). A two year moving average is included to better illustrate the trend. Reference line is the mean (source: UK Met Office) Rainfall Since 1961 all regions of the UK have experienced an increase in annual rainfall, ranging from 3% in London to 23% in the North and West of Scotland. Conversely most regions have experienced reduced rainfall during the summer months. Since 1961 London has experienced 17% less summer rainfall. In contrast there has been a 5% increase in the East of England (Jenkins et al., 2007). The overall trend for a reduction in summer rainfall has led to an increase in the number of drought days, with hosepipe bans now a matter of course for those living in the southeast of the country. The winter months however, have seen an increased trend in the amount of rainfall in all regions of the UK, from 11% in the Midlands to 66% in North Scotland since 1961 (Jenkins et al., 2007), with 2000 the wettest year recorded in the 20 th century in England and Wales. The intensity of rainfall has also increased with the 16

18 last 40 years seeing an increase in the contribution of intense storm events to the overall total (e.g. the flooding in southern England in 2000 and west central England in 2007). 1.5 Climate change scenarios for the UK UKCIP has produced 4 scenarios of climate change for the next 100 years at a 50 km spatial resolution (Hulme et al., 2002) (UKCIP02, and available online at: The models used to develop these scenarios are based upon future GHG emissions estimates which may be the result of future global rapid economic growth and intensive fossil fuel use (high emissions), or conversely a future of increased economic, social and environmental sustainability with cleaner energy technologies (low emissions), UKCIP also employs medium-low and medium-high emissions scenarios. In common with the IPCC SRES scenarios, those used in UKCIP are all considered equally likely. Projections are made for three different time-slices: (2020s), (2050s) and (2080s). Each scenario assesses just how global warming might affect the UK on a regional 2 scale during the 21 st century. However before the model can be used to predict climate change it is important to evaluate the extent to which they simulate the observed climate. Figure 1.4 compares the average winter and summer precipitation record for the UK for the baseline period used by UKCIP and the simulated values. As can be seen, the model simulates the observed precipitation record very well, highlighting the differences in precipitation across the UK. 2 East Midlands, East of England, London, North East, North West, Northern Ireland, Scotland, South East, South West, West Midlands, Wales and Yorkshire and Humber. Data is also available for England. 17

19 Figure 1.4. Comparison of average winter and summer precipitation records for the observed baseline period (left) and simulated values (right) (source: UKCIP02). Work is currently underway on the next series of scenarios, available sometime in 2008 (UKCIP08). These will be based on more up-to-date data and provide more detailed information on the anticipated effects of climate change at a much higher spatial resolution. In the meantime UKCIP s work already identifies the challenges that lay ahead from a climate change perspective Sources of uncertainty and level of confidence in UK climate projections The complex nature in which future climate change projections are obtained mean that uncertainties exist, these include: Uncertainty about global future socio-economic development and the subsequent consequences for GHG emissions; The response of different climate models; 18

20 The effects of natural climate variability; Downscaling global changes to a regional or local level. Most global climate models (GCMs) produce data on a coarse 300 km resolution, however downscaling is employed to obtain data at a 50 km resolution (as is the case with the UKCIP02 scenarios). This is a complex process which must consider natural variability of both land and atmosphere; Possible changes in the Gulf Stream 3. The UKCIP02 scientific report does not assign probabilistic distributions to its climate projections this has however been addressed by the CRANIUM project (Climate change Risk Assessment: New Impacts and Uncertainty Methods By using a range of regional climate models, probabilities have been developed for a range of future climatic parameters at 10 locations of interest for built environment research for the 2080s time-slice these include: Birmingham, Gatwick, Glasgow, Heathrow and Manchester. Consequently by the 2080s CRANIUM estimates that there is a 31% chance that maximum summer temperatures at Gatwick Airport will increase by between 4 and 5 C and a 54% chance that the increase will be between 4 C and 6 C (figure 1.5). In order to enable decision makers to consider probabilities and possible consequences, UKCIP08 is committed to publishing probability estimates such as these. 3 UKCIP02 does however state that while the strength of the Gulf Stream may weaken in the next 100 years it is unlikely that this would lead to a cooling of the UK climate over this time-frame. 19

21 Probability (%) % 31% 23% 20 8% 10% 10 4% 0% 1% 1% 0% Degrees C Figure 1.5. Probability of getting a certain change in mean maximum summer temperature at Gatwick Airport in 2080 under the IPCC A2 scenario (equivalent to UKCIP02 medium-high emissions scenario) (source: The UKCIP02 Scientific Report however attaches levels of confidence (high, medium or low), to a selected set of qualitative statements made about future climate change in the UK. These are not quantitative and are based on the authors knowledge of the physical reasons for changes, the degree of consistency between different climate models and an estimate of the statistical significance of the results. For example, they report a high level of confidence that precipitation intensity will increase in winter. Conversely there is a low level of confidence that winter depressions will become more frequent. Confidence levels for climate projections can be found at the end of this section in table Temperatures The UKCIP02 climate change scenarios for the UK estimate that by the 2020s mean annual temperatures will have risen between 0.6 C and 0.9 C (low emissions) and between 0.7 C and 1.0 C under the high emissions scenario. The nature of the baseline period used by UKCIP02 ( ) and the future scenarios mean that changes for the 2020 time slice (which represents the period ) are already underway. For example, scenarios for the 2020s indicate that the southeast of England can expect mean annual temperatures to rise between 0.9 C (low emissions) and 20

22 1.0 C (high emissions) However mean annual temperatures in this region for the period were already 0.78 C higher than the modelled baseline figure (Perry, 2006). By the 2050s mean annual temperatures will have risen by 1.0 C to 1.6 C (low emissions) and 1.7 C to 2.5 C (high emissions) depending upon the region. By the 2080s mean annual temperatures may have increased by between 1.0 C and 2.2 C (low emissions) to between 2.9 C and 4.3 C (high emissions) in all cases the most extreme effects will be felt in the south of the country (figures 1.6 and 1.7) Summer temperatures The 2020s will experience increased summer temperatures of between 0.6 C and 1.1 C (low emissions), rising to between 0.8 C and 1.3 C (high emissions). Temperature rise will be lowest in Northern Ireland, Scotland and Northern England, while the highest temperature increases will be in London and the south (figures 1.6 and 1.8). By the 2050s average summer temperatures are expected to increase by between 1.1 C to 2 C (low emissions). This will rise to 1.6 C to 3.2 C under the high emissions scenario, with the south of the country continuing to experience the largest increase (figures 1.6 and 1.8). By the 2080s, average summer temperatures are also expected to increase by between 1.6 C and 2.8 C (low emissions) and 2.5 C to 5.4 C (high emissions) depending upon the region, as are the number of extremely warm summer days (i.e. a daily average temperature above 23 C in the south east and 17 C in Scotland), by 12 days (low emissions) to 30 days (high emissions) in England, and 6 days (low emissions) to 30 days (high emissions) in Scotland. Projections also indicate that by the 2080s the average daily temperature threshold for an extremely warm summer day in England will have increased from 23 C to around 27 C (low emissions) or 31 C (high emissions). Hot summer days with temperatures similar to those recorded in August 2003 and July 2006 (i.e. > 3 C above average) are also expected to be common by the end of the 21 st century Winter temperatures Winter temperatures also display a northwest to southeast gradient. By the 2020s winter temperatures are estimated to increase by between 0.5 C and 1 C under both the low and high emissions scenarios. By the 2050s winter temperatures across the UK are likely to have increased by 0.5 C and 1.5 C (low emissions) to 1 C and 2 C 21

23 (high emissions) and by the 2080s increases of 1 C to 2 C (low emissions) to 2 C and 3.5 C (high emissions) are likely. The number of very cold winter days is expected to decrease, with temperatures similar to those in January/February 1963 (i.e. > 3 C below average) likely to become highly uncommon by the end of this century. There is also expected to be a greater amount of warming at night in winter conversely during the summer warming will be greatest during the day. However, the UKCIP02 scenarios do not take into account the urban environment e.g. the Urban Heat Island (UHI) and the effect that it may have on its own localised climate, hence projected average temperatures will be the same for central London as they are for the surrounding rural areas. For example the average maximum summer temperature for the baseline period recorded in Greenwich, London, was 21.4 C ( compared with the UKCIP estimate of 20 C. The effect of the UHI will be greatest in summer afternoons and evenings: during the heat wave in August 2003, night time temperatures in central London were as much as 9 C higher than those recorded in Wisley, Surrey, approximately 50 km to the west. This issue has been a focus of the BETWIXT project (Built EnvironmenT: Weather scenarios for investigation of Impacts and extremes; which uses the UKCIP scenarios to provide daily and hourly estimates of climatic conditions throughout the next century. Simulations have indicated that modified urban landscape effects cause urban areas to be warmer than surrounding non urban areas during both the present day and under a high emissions scenario in the 2080s (Goodess et al., 2007); consequently urban areas are likely to have temperature increases over and above the UKCIP02 projections. 22

24 Figure 1.6. Mean annual (top panel) and summer temperature change (lower panel) under low and high emissions scenarios (compared with the average) across the UK during the 21 st Century (source: 23

25 1.20 Temperature change (degrees centigrade) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High 3.0 Temperature change (degrees centigrade) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High 5.0 Temperature change (degrees centigrade) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High Figure 1.7. Annual temperature change ( C) from the modelled baseline across the UK for the 2020s (upper panel), 2050s (middle panel) and 2080s (lower panel) (source: UKCIP02). 24

26 1.4 Temperature change (degrees centigrade) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High 4.0 Temperature change (degrees centigrade) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High 6.0 Temperature change (degrees centigrade) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High Figure 1.8. Summer temperature change ( C) from the modelled baseline across the UK for the 2020s (upper panel), 2050s (middle panel) and 2080s (lower panel) (source: UKCIP02). 25

27 1.5.3 Rainfall Rainfall is expected to increase during the winter months and decline in the summer, so much so that there will be increased drought conditions in the southeast (figures 1.9, 1.10 and 1.11); consequently summers similar to that in 1976, when standpipes were, for a period, the sole source of water for many households, can be expected to increase in frequency. Despite increasing rainfall during the winter, it is anticipated that annual rainfall will decline for all parts of the UK (figure 1.10). By the 2020s this may be between 0.7% and 2.5% (low emissions) and 0.8% to 3% (high emissions). As with temperatures there is a north-south gradient with the greatest reductions in rainfall anticipated to occur in London and the south. By the 2050s southern England may experience reductions of 4.5% (low emissions) and 7% (high emissions) compared with just 1.3% and 2% in Scotland. Rainfall may have declined by 6.4% (low emissions) and 12.4% (high emissions) in south west England by the 2080s. Meanwhile under the high emissions scenario, annual rainfall across Scotland is anticipated to fall by just 3.5% Summer Rainfall By the 2020s summer rainfall may have declined by 5.9% (range 4 1 to 9%) across Scotland and between 8% and 10% in much of the rest of the country under the low emissions scenario (figures 1.9 and 1.11). Under the high emissions scenario Scotland may see reductions of 7% (range: 1 to 10%) with London and the south of the country experiencing around 12% less rainfall. By the 2050s, summer months under the low emissions scenario may see a 10% (range: 2 to 15%) decline in rainfall across Scotland and an 18% decline in the south of the UK. Under the high emissions scenario 17% less rainfall can be expected across Scotland, (range: 3 to 24%) and up to 30% in the south west. By the 2080s, the summer months in Scotland may be characterised by 15% (range: 3 to 21%) less rainfall and southern England by around 25% less rainfall (low emissions). Rainfall values will decline by 30% (range: 6 to 41%) in Scotland and as much as 50% in southern England under the high emissions scenario. 4 The ranges given here are spatial rather than probabilistic. For example most of Scotland will experience a small decline in summer rainfall under the 2020 low emissions scenario, there are however some areas of central and southern Scotland where rainfall decline may be more severe. This is also the case in Northern Ireland although not to the same extent. In the rest of the UK the ranges are much smaller, typically a maximum of 2-3% either side of the mean values given here. 26

28 Winter Rainfall Under the low emissions scenario the whole of the UK can expect around 4% more rainfall in the winter months by the 2020s (figures 1.9 and 1.12). This will remain the same for Scotland (range: 0 to 8%) under the high emissions scenario. However eastern and south east England can expect increases of around 6% By the 2050s winter rainfall can be expected to increase by 6% (range: 0 to 12%) in Scotland and Northern Ireland and by around 8% for much of England and Wales (low emissions). This will rise to around 10% (range: 1 to 20%) and 14% for the same regions (high emissions). By the 2080s, winters may see increased rainfall of around 9% (range: 1 to 17%) across Scotland to 12% in the south and the east of the country (low emissions). Under the high emissions scenario rainfall values increase by 17% (range: 1 to 33%) across Scotland and Northern Ireland and 25% in the southeast. More frequent intense storm events and heavy rainfall are also projected. By the 2080s, winter daily precipitation intensities that are experienced once every two years on average may become up to 20% heavier. 27

29 Figure 1.9. Mean summer (top panel) and winter precipitation change (lower panel) under low and high emissions scenarios (compared with the average) across the UK during the 21 st Century (source: 28

30 0.0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Change in annual rainfall (%) Low Region High 0.0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber -1.0 Change in annual rainfall (%) Low Region High 0.0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Change in annual rainfall (%) Low Region High Figure Change in annual rainfall from the modelled baseline across the UK for the 2020s (upper panel), 2050s (middle panel) and 2080s (lower panel) (source: UKCIP02). 29

31 0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Change in summer rainfall (%) Low Region High 0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Change in summer rainfall (%) Low Region High 0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Change in summer rainfall (%) Low Region High Figure Change in summer rainfall from the modelled baseline across the UK for the 2020s (upper panel), 2050s (middle panel) and 2080s (lower panel) (source: UKCIP02). 30

32 8 7 Change in winter rainfall (%) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High Change in winter rainfall (%) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High Change in winter rainfall (%) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High Figure Change in winter rainfall from the modelled baseline across the UK for the 2020s (upper panel), 2050s (middle panel) and 2080s (lower panel) (source: UKCIP02). 31

33 1.5.4 Soil moisture Despite increased winter precipitation by the 2020s annual reductions in soil moisture, an important factor in building stability, may be between 5% (low emissions) and 6% (high emissions) in London and the south east. By comparison soil moisture reduction in Scotland is between 1% and 2% under both emissions scenarios (figure 1.13). By the 2050s annual reductions in soil moisture may be as high as 15% (high emissions) in the south of the country, yet just 4% in Scotland. By the 2080s soil moisture content may still be between 12% (low emissions) and 25% (high emissions) lower than the modelled baseline due to warmer temperatures and higher rates of evaporation in southern parts of the UK. Conversely reductions in Scotland may be just 4% (low emissions) to just 7% under the high emissions scenario Summer soil moisture The increase in temperatures and reduced summer precipitation will contribute to a reduction of summer soil moisture throughout the next century (figure 1.14). By the 2020s average summer soil moisture across Scotland may be reduced by 3% under the low emissions scenario while much of the eastern and southern UK will experience reductions of 8 to 9%. Under the high emissions scenario soil moisture content may have been reduced by around 4% across Scotland and 11% in southern England. Reductions of 6% and 16% are projected for Scotland and the south of the country respectively by the 2050s (low emissions) and 9% and 25% for the same regions under the high emissions scenario. By the 2080s soil moisture may be reduced by 16% across Scotland and 45% in southern parts of the UK (high emissions). Even under the low emissions scenario the reduction may be as much as 20% for much of England. 32

34 0.0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber -1.0 Soil moisture reduction (%) Low Region High 0.0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber -2.0 Soil moisture reduction (%) Low Region High 0.0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Soil moisture reduction (%) Low Region High Figure Annual average soil moisture reduction from the modelled baseline across the UK for the 2020s (upper panel), 2050s (middle panel) and 2080s (lower panel) (source: UKCIP02). 33

35 0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Soil moisture reduction (%) Low Region High 0 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Soil moisture reduction (%) Region Low High 0-5 UK England N. Ireland Scotland Wales East Midlands East England London North East North West South East South West West Midlands Yorks. & Humber Soil moisture reduction (%) Region Low High Figure Average summer soil moisture reduction from the modelled baseline across the UK for the 2020s (upper panel), 2050s (middle panel) and 2080s (lower panel) (source: UKCIP02). 34

36 1.5.5 Winter wind speeds By the 2020s the highest increases are expected to occur in the south east with wind speeds around 1.4% and 1.6% higher than the modelled baseline under the low and high emissions scenarios respectively (figure 1.15). In Scotland and Northern Ireland these increases are negligible. By the 2050s, it is estimated that winter wind speeds may increase by between 2.4% and 3.9% in the south east under the low and high emissions scenarios respectively. In Scotland and Northern Ireland wind speed increases remain below 1% under both scenarios. By the 2080s average wind speeds during the winter months may increase by between 3% and 7% in London, the east of England and along the south coast. In terms of daily wind speeds, during the winter these might be expected to increase by between 2 and 6% in southern England. However there is a great deal of uncertainty associated with estimates of future wind speed (table 1.3) and UKCIP02 stresses that little or no confidence exists in simulated wind speed projections and that more caution should be taken when using these results as opposed to those for rainfall and temperature. 35

37 Wind speed increase (%) UK England N. Ireland Scotland Wales East Midlands East England London Region North East North West South East South West West Midlands Yorks. & Humber Low High Wind speed increase (%) UK England N. Ireland Scotland Wales East Midlands East England London Region North East North West South East South West West Midlands Yorks. & Humber Low High Wind speed increase (%) UK England N. Ireland Scotland Wales East Midlands East England Region London North East North West South East South West West Midlands Yorks. & Humber Low High Figure Average winter wind speed change across the UK for the 2020s (upper panel), 2050s (middle panel) and 2080s (lower panel) (source: UKCIP02). 36

38 1.5.6 Seasonality and inter-annual variability In seasonal terms, the 2050s may see typical spring temperatures occurring between one and three weeks earlier than the present day, similarly the onset of winter temperatures may be delayed by one and three weeks. Inter-annual variability (i.e. the seasonal variations in temperature and precipitation from year to year) is also likely to change with summer temperatures over much of the UK being 20% more variable in summer and autumn (high emissions) by the 2080s. Similarly the inter-annual variability of precipitation in winter increases for most of the country. This is most marked along the east coast where inter-annual variability of precipitation may increase by more than 25% (high emissions). Despite the rising temperature trend along with increased (winter) and decreased (summer) precipitation throughout the 21 st century, it is not expected that every year will be warmer than the next or that every summer will be drier than the previous summer. Climate will be changing from year to year as it does now. The modelling of future climate for specific years is not yet possible however an estimation of variability can be obtained. This is well illustrated by the simulation of climate on a day by day basis throughout the 21 st century. Possible precipitation and temperature simulations using the medium-high emissions scenario are shown in figure For both precipitation and temperature, trends are apparent however underlying these trends is year on year variability. Consequently there may be years in the future where little or no warming is recorded while in other years summer rainfall may be higher than expected (e.g. summer 2007). 37

39 Figure Possible evolution of winter and summer mean temperature (left panel) and precipitation (right panel) from for England and Wales under the medium-high emissions scenario. The seasonal anomalies are calculated with respect to the baseline. The stars indicate years in which the model simulates the setting of new warm, dry or wet records. The smooth curves illustrate the variations on time scales of more than 10 years. This data is not to be interpreted as forecasts for specific years (source: UKCIP02) The North Atlantic Oscillation and storm events Many aspects of the UK climate during the winter months and indeed that of the entire extra-tropical North Atlantic are influenced by the North Atlantic Oscillation or NAO, an oscillation in the pressure gradient between the Azores and Iceland which is measured as the difference in sea-level pressure between these two locations. The corresponding index which measures the strength of the oscillation varies from year to year but also has a tendency to remain in one phase (i.e. positive or negative) on a decadal scale. Positive phases of the NAO, as has been the case for most of the last 30 years, are associated with low pressure over Iceland and high pressure over the Azores (figure 1.17). Air travels counter-clockwise around low pressure systems consequently strong westerly winds transport warm and moisture laden air masses over Northern Europe which results in mild, wet winters; meanwhile southern Europe remains drier and colder. Conversely during a negative phase of the NAO the pressure gradient between Iceland and the Azores is much reduced (figure 1.17), consequently the westerly winds and the warm, wet air that they transport are displaced further south with much of southern Europe having warm and wet winters. In contrast Northern Europe will be subjected to the southerly movement of cold air from the arctic and 38

40 also on occasion fall under the influence of the Siberian High Pressure system and as a result experience cold, dry winters. During winter the UK weather is dominated by depressions or lows, moving in from the North Atlantic so there is some correspondence with the NAO (Hulme et al., 2002). These may increase from an average of 5 during the present UK winters to around 8 (medium-high emissions scenario) by the 2080s. The associated low atmospheric pressure and winds can result in storm surges (temporary increases in sea level) which occur in shallow water regions such as the continental shelf around the UK. One such event in 1953 killed 300 people on the North Sea coast and the Thames Estuary, and led to the design and construction of the Thames Barrier. UKCIP02 does not produce direct simulations of storm surge height however the largest increases of surge height might be expected to occur off the south east coast. Simulated changes for the NAO under the medium-high scenario until 2100, indicate that the positive phase is likely to continue (although there will be year on year variability) as such there is an increased likelihood that UK winters will become more westerly in nature and that winters will become milder, wetter and windier which is consistent with UKCIP02 predictions. 39

41 Figure Positive (top panel) and negative phase (lower panel) of the NAO and subsequent effect upon the transport of moisture, illustrated by white arrow across Scandinavia, Europe and North Africa. See text for details. Image created 08/11/07 and provided by the NOAA-CIRES Climate Diagnostics Center, Boulder Colorado from their Web site at Sea Level Rise Sea-level rise in the UK over the next 100 years is dependent upon three factors: thermal expansion of ocean water, the melting of land-based glaciers and subsequent regional land movements due to the readjustment of land after deglaciation around 10,000 years ago. During a typical glacial cycle mean global sea-levels may be lowered by between m (Milne and Shennan, 2007). The redistribution of this water to the land surface in the form of ice and its great weight, leads to significant deformation of the land surface due to the viscous nature, on a geological timescale, of the Earth s mantle. As a result those areas covered by ice sheets (e.g. Scotland where ice sheets 22,000 years ago may have been around 1 km thick) will be subjected to subsidence, whereas those regions peripheral to the ice sheets (e.g. southern England 22,000 years ago) will experience uplift. As climate changes and deglaciation occurs this process is reversed. Presently uplift is occurring at a rate of 0.8 mm each year in Scotland while the south west has an annual subsidence rate of 1 mm (table 1.2). 40

42 Table 1.2. Rates of vertical land movement (mm/year) due to isostatic adjustment after deglaciation for the administrative regions of England and the devolved administrations of Scotland and Wales. Anticipated sea level change under the IPCC low and high emissions scenarios relative to the baseline period are also shown (source: UKCIP02) Region Subsidence (-) uplift (+) Low Emissions High Emissions East England East Midlands London North East North West Scotland South East South West Wales Yorks. and Humber West Midlands No coastline or tidal estuaries (at present time) N. Ireland No isostatic adjustment data available Consequently while Scotland may experience increased sea levels of up to 0 to 61cm by 2080, sea-level rise in southeast England is likely to be in the range of 14 74cm (depending upon scenario, figure 1.18). Even if GHG concentrations are stabilised, thermal expansion will continue as heat is slowly transferred to the deep ocean. Analysis also indicates that by the end of the 21 st century, extreme sea levels due to severe storm surge events could be 20 times more frequent for some coastal locations depending upon the emissions scenario. 41

43 Figure Estimates of relative UK sea level rise throughout the 21 st century (source: 42

44 Table 1.3. Confidence levels associated with UKCIP summary statements (source: UKCIP02). Temperature Variable and scenario Annual warming by 2080 of between 1 and 5 C depending upon region and scenario Greater summer warming in the southeast than the northwest Greater night-time than day-time warming in winter Greater warming in summer and autumn than in winter and spring Greater day-time than night-time warming in summer Number of very hot days increases, especially in summer and autumn Number of very cold days decreases especially in winter Heating degree days increase everywhere Cooling degree days increase everywhere Precipitation and moisture Generally wetter winters for the entire UK Substantially drier summers for the entire UK Precipitation intensity increases in winter Decreased soil moisture during summer and autumn in the southeast Increased soil moisture during winter and spring in the northwest Depressions and wind speeds Winter depressions increase in frequency Increased wind speeds Sea level change Will continue to rise for centuries and probably longer Continuation of historic trends in vertical land movements will introduce significant regional differences in relative sea level rise around the UK Extreme sea levels and more frequent storm surge events for some coastal locations Relative confidence level H H L L L H H H H H M H H M L Uncertainty exists H H M 43

45 1.6 Summary It is clear that over the last 150 years or so the earth s climate has been changing, furthermore it now appears almost certain that these changes have been brought about by anthropogenic activity and that our climate will continue to change over the course of the present century whether or not greenhouse gas emissions are stabilised. As far as the United Kingdom is concerned, UKCIP projections indicate that the forthcoming century will be one of change with particular emphasis on rainfall, soil moisture temperature, sea level and wind (although as already stated while increases in wind speed exist, there is uncertainty as to the extent of these changes). As projected changes on a global scale are likely to differ, the 50 km resolution used in the UKCIP scenarios also permits projections of change on a region by region basis within the UK enabling us to see a north-south divide, with the latter region most likely to suffer from the effects of higher temperatures, higher winter rainfall, increased drought and reduced soil moisture. However it is clear that no region of the UK will be immune from the effects of global warming. 44

46 2. Vulnerability of UK Property to Climate Change Section 1 has outlined and summarised the key features of future climate change. Of vital importance is whether these changes create negative impacts in the UK and how vulnerable the property sector within the UK is to these negative impacts. This section discusses vulnerability to climate change impacts, considering the risk to the property sector from changes in temperature, precipitation, soil moisture and wind speed. The different types of property residential, office/business parks, industrial, warehousing/distribution and retail are then discussed, before turning to the vulnerability of the different infrastructure systems. Finally this section discusses the role of property insurance in relation to these climate change risks to property. 2.1 Vulnerability and Climate Change Impacts In discussing the UK s future climate, UKCIP underlines that there will be both positive and negative impacts. It summarises the positive impacts of predicted climate change as: - An increase in tourism and leisure - Less cold-weather disruption to transport - Reduction in cold-related illness and deaths - Benefits for agriculture including: o Enhanced agricultural and horticultural yields o Ability to grow new crops o Longer growing season However, the negative impacts are more numerous and extensive: - Impacts on public health and comfort o Increase in hot-weather health problems o Increase in demand for cooling o More pests - Increased risk of flooding: o From increased rainfall levels o From an increase in intense rainfall events o Increase in risk of sewer overflows o Increased risk of coastal flooding and erosion - Impacts on water management o Increased risk of water shortages 45

47 o Increase in low river flows and water quality problems o Increase in need for water management from changes in seasonality - Impacts on ground conditions o Reduction in soil moisture leading to an increase in subsidence o Increased variability in soil moisture leading to an increase in ground movement o Increase in soil erosion and pollutant leaching - Increase in risk of damage to essential infrastructure from intense rain events - Impacts on biodiversity o Change in species and habitats o Increase in loss of coastal habitat o More Source: Many of these impacts will affect the UK property sector, some indirectly through changes in the UK economy (e.g. the likely changes in tourism and leisure patterns) and others directly, through the physical impact on the built environment. In the following discussion the emphasis is on the direct physical impacts. In particular the discussion focuses on the vulnerability of the property sector to these physical climate change risks. Vulnerability can be defined as: the exposure to contingencies and stress, and difficulty in coping with them. Vulnerability thus has two sides: an external side of risks, shocks and stress to which an individual or household [or company] is subject; and an internal side which is defencelessness, meaning a lack of means to cope without damaging loss. (Chambers, 1991, p.1 quoted in Lisø et al., 2003 In discussing the vulnerability of the property sector to climate change, we need to consider the features of the sector and the physical buildings that render it more or less likely to be able to cope with these impacts 5. 5 Heritage buildings may be particularly vulnerable to changes due to their design and construction methods and the limited possibilities for mitigation within the constraints of conservation policies. These are not specifically considered in this report. 46

48 2.1.1 Vulnerability of property to changes in temperature The increase in baseline temperatures will lead to overheating in buildings in summers. This will be exacerbated in urban areas where the urban heat island effect may lead to increased temperatures in the city centre in contrast to the rural hinterland. As well as making life in affected areas more uncomfortable, increased temperatures are likely to lead to increased demand for artificial cooling, in both domestic and commercial settings with consequent capital 6 and operational costs. More seriously, the more frequent incidence of heat waves will turn periods of discomfort into periods of public health crisis, with increased levels of deaths, particularly among the elderly. The summer heat wave of 2003 resulted in some 2100 excess deaths across the UK, with deaths of the over 75s in London increasing by 59% (Johnson et al., 2005); during this period night-time London temperatures were recorded as being up to 9 o C higher than in rural Surrey. Workplaces will also be affected by heat waves through potential loss of working days though these are likely to be relatively short-term problems. The extent to which a particular building is vulnerable to extreme heat events and to the cooling demands of increased temperatures depends on the construction of the building and, in particular, its thermal mass. Timber-framed constructions, for example, have less thermal mass than concrete or masonry buildings and this increases the need for artificial heating in winters and artificial cooling in summers (Arup R&D, 2007). A similar point can be made about lightweight shed constructions typical of many industrial and warehousing properties. Glass curtain walling with the masonry mass in the centre of the building (as with many office buildings) is also less thermally effective in hot conditions than having thermal mass in the roof and ceilings with natural ventilation to remove stored heat. Research on the most effective building design from a thermal mass perspective is still ongoing. There are two other risks related to higher temperatures that will affect property. The first comes from the effect of increased UV radiation on paintwork and exterior finishes, leading to the requirement for more frequent maintenance of properties. Solar radiation is expected to increase over all the UK in the summer but especially in 6 Additional capital investment may be required as existing air conditioning will fail more frequently under heat wave conditions. 47

49 the South where UKCIP02 anticipates around a 15% reduction in cloud cover by the 2080s. The second concerns the possibility of changed temperatures favouring pests. Higher temperatures may increase the risk of aggressive insect infestation, such as wood-boring and other invasive insects Vulnerability of property to changes in rainfall The impact of changed rainfall patterns that is most commonly highlighted is the enhanced flood risk. This can arise from increased run-off in urban locations exceeding the capacity of urban drainage systems and from rivers breaking their banks due to run-off into upstream riverine systems 7. Such flooding risks are highly location specific and the key issue is the growing extent of property within flood risk areas as intense rainfall events multiply. Construction type can affect vulnerability to flooding, quite apart from any specific flood-proofing measures that may have been incorporated 8. Lightweight buildings are more likely to be damaged in floods than masonry construction; however framed, modular constructions may also be easily re-instated after flooding (Sanders and Phillipson, 2003). It should be remembered that the costs of flooding are not just due to water damage and loss of occupance. Run-off from agricultural land can be highly corrosive and sewers often back-up during flood episodes, leading to contamination from sewerage (Sanders and Phillipson, 2003). Demountable constructions may be more readily cleaned and replaced if contaminated. Changing rainfall patterns also create problems for water management with greater fluctuation in water supply over time and space, and with the likelihood, in some locations, of periodic droughts. Reduced soil moisture during drought periods may reduce the penetration of subsequent rainfall into the water table, with water instead contributing to greater run-off; potentially exacerbating problems of water management. All these features are likely to lead to increased water supply costs. The significance for the property sector will clearly depend on the extent to which occupiers require water supplies and the centrality of water to the efficient functioning of the property. 7 Flooding in coastal locations can also result from sea level rise, coastal erosion, and tidal and storm surges; these are outsite the remit of this report. 8 These would include: waterproof boarding and plaster; solid and sealed or drainable floors, waistlevel electrics; sealable doors. 48

50 Driving rain is another feature of intense rain events (quite independent of any change in wind speed see below) and this will have a detrimental impact on property. There will be more risk of water penetration through exterior walls; when added to frost damage, this can affect the integrity of the building surface. Driving rain will affect properties with rendered walls to a greater extent than those with cladding (Lisø et al, 2003). Cavity wall insulation (often recommended to increase the thermal efficiency of buildings) may actually render buildings more vulnerable to rain penetration in conditions of driving rain. Increased cavities and gaps in the insulation may be needed to address this problem (Sanders and Phillipson, 2003). The capacity of guttering is also a key issue in preventing property damage. Local designs have often traditionally coped with existing patterns of driving rain, e.g. the use of recessed windows in Scotland. However, it is anticipated that the greatest increase in winter driving rain will be in London (Sanders and Phillipson, 2003) and there may be the need to learn from other regions in the UK just how to protect buildings from this risk. Changes in temperature and rainfall patterns will combine to alter humidity and internal moisture levels. The absolute amount of humidity in the atmosphere will increase over the year, although relative humidity may decrease in the summer months (UKCIP02). Milder winters with higher absolute humidity are most likely to favour mould growth, with consequent health impacts, although this might be mitigated if wind speeds do increase and allow more effective ventilation in nonsealed buildings (Sanders and Phillipson, 2003). 49

51 2.1.3 Vulnerability of property to changes in soil moisture One important consequence of changed rainfall patterns is the expected reduction in soil moisture. In areas built upon clay soils, this will lead to enhanced risk of ground movement and subsidence. Subsidence is already a significant problem for property. The two droughts in the 1990s led to property-linked losses of over $2.5 billion in the UK (Mills, 2003), while in 2003 it was estimated that subsidence insurance claims for private housing amounted to about 400 million p.a. (Sanders and Phillipson, 2003). Graves and Phillipson (2000) estimated that there could be a % increase in subsidence claims in vulnerable areas in the south of England due to dryer summers. The incidence of this hazard depends on location and underlying geology but the vulnerability of property depends greatly on the construction methods adopted and, in particular, the way that the foundations to the property have been constructed. Foundations in buildings since the turn of the 20 th century have typically been based on concrete blocks, poured concrete slabs or piling. 19 th century buildings may well be particularly vulnerable depending on how far local knowledge informed construction methods. Buildings constructed up to the early 1970s will exhibit variable resilience in the face of ground movement in clay-based areas depending on the foundations used. Buildings dating from the immediate post-war period are most likely to be particularly poorly constructed in these terms; many of these buildings are approaching or have passed their economic lifespan and are found in more secondary and tertiary locations. A quarter of the total industrial and commercial floorspace, and a half of industrial and commercial buildings date from pre-ww2; a further quarter of the total floorspace and a fifth of the buildings were built between 1940 and 1970 (ODPM statistics, 2004). However the pattern of existing foundations across the UK property stock is not just a matter of technology; equally important is the way that construction management practices have favoured certain approaches to constructing foundations. This suggests that ground movement may be less of a problem for post-1970s commercial property. The 1980s saw a shift in management practices in the commercial sector towards fasttracking, whereby different elements of the building were planned and commissioned simultaneously. This led to a degree of over-engineering and rather monumental buildings, with large floorspans, heavy mass, and considerable servicing. In such 50

52 buildings, foundations are likely to exceed technical requirements. Therefore, while these buildings may be verging on the redundant from the occupiers point of view, they may actually be more robust in the face of changes in soil moisture. From about the mid-1990s onwards, there has been a shift in construction management practices towards more carefully designed buildings which use innovative methods, including piling, to reduce the amount of concrete in foundations. However, these buildings are not necessarily less resilient since the costs of marginally increasing foundation depth when using piling are not large and most modern commercial buildings should be able to cope with expected soil movement, provided that a margin has been designed into the piled foundations. One feature that is difficult to predict in relation to ground movement is the role of vegetation. More aggressive plant growth can cause greater incidence of root damage to buildings. Trees dying back or being cut down will reduce the water take-up in the soil and may reduce the risk of ground shrinkage in clay soils. However, the death of trees can also cause damage through the subsequent relatively sudden rehydration of soils (Sanders and Phillipson, 2003). Furthermore, in urban spaces trees will play an important role in providing shade and comfort as temperatures increase throughout the present century Vulnerability to of property changes in wind speed As discussed in section 1, the predicted changes in wind speed have been shown to be one of the more uncertain aspects of future climate change. In addition the percentage increases on baseline wind speeds do not suggest a very substantial impact, compared to the other climate change risks reviewed. However, there is some evidence that even a small increase in wind speed may cause property damage. An increase of wind speed of 6% may cause damage to up to 1 million buildings, costing between 1-2 billion (Graves and Phillipson, 2000). In 2003 it was estimated that the average number of wind damage events each year was already approximately 200,000, amounting to an estimated cost of 70 million (Sanders and Phillipson, 2003). Individual large-scale events can increase this 51

53 considerably; the 1987 storm affected 6% of the domestic housing stock, over 1.3 million houses (ibid). Even though increases in wind speed are uncertain, the possible level of damage means that this risk is still worth taking into account (Sanders and Phillipson, 2003). This involves considering the robustness of different construction methods to wind speed. For example, older properties or those built in periods of poor construction quality (such as the 1950s) may be less robust in the face of higher winds. Regulation is also important, assuming that they are effectively implemented. Scottish Building Regulations require a greater ability to cope with wind and so Scottish buildings should be more resilient. However, current Building Regulations calculate wind loads on the basis of certain assumptions about the directionality of wind. If, as it likely, this directionality changes, then the current regulations may be underdesigning buildings for resilience against wind by as much as 50% in wind load (Sanders and Phillipson, 2003). In addition, many building failures in the face of wind are because construction has not been to the required standard due to poor workmanship and design practices (ibid). 2.2 Climate Change Risks and UK Property Types The above discussion has considered the impact of climate change on UK property in general. Attention now turns to the different types of property. Table 2.1 summarises the vulnerability of the different UK property types to the risks arising from climate change using High/Medium/Low categories. These were ascertained through examination of the literature and peer review. These risks are expanded on below. 52

54 Table 2.1 Vulnerability of property types to climate change risks Climate Change Risk Increased baseline temperatures leading to increase in internal temperatures Heat waves causing heat stress to occupants Extreme rainfall events leading to flooding in areas at risk from urban flashfloods or river overflow Drought periods affecting water supplies Reduced soil moisture leading to ground movement in clay soils Increased wind speeds leading to structural damage Residential MEDIUM Comfort affected leading to demand for cooling MEDIUM Health of vulnerable groups at risk HIGH Only in certain locations; current coping strategies are weak MEDIUM Only in certain locations MEDIUM Only in certain locations; older properties particularly affected LOW/MEDIUM Older properties mainly at risk Offices and Business Parks MEDIUM Internal comfort affected in buildings with low thermal mass MEDIUM/HIGH May disrupt hours of occupancy or generate employer liabilities HIGH Only in certain locations; current coping strategies are weak LOW/MEDIUM Only in some locations LOW Only in certain locations and in a limited part of stock LOW Limited impact Industrial LOWMEDIUM May affect some industrial processes and working conditions MEDIUM Some processes disrupted HIGH Only in certain locations; current coping strategies are weak MEDIUM Dependent on industrial process LOW Only in certain locations and in a limited part of stock LOW Limited impact Warehouses/ Distribution MEDIUM May affect storage costs for some products MEDIUM Some products severely affected HIGH Only in certain locations; current coping strategies are weak LOW Limited water usage LOW Only in certain locations and in a limited part of stock LOW Limited impact Retail LOW/MEDIUM May affect customer comfort. Potential positive feature in high street HIGH + LOW High streets adversely affected to benefit of shopping malls/centres HIGH Only in certain locations; current coping strategies are weak MEDIUM Only in certain locations; higher water usage than offices LOW/MEDIUM Only in certain locations; only likely to affect older high street properties LOW/MEDIUM Older and high street properties only at risk 53

55 2.2.1 Residential property Changed temperature patterns will affect the internal comfort of housing. The nature of the built form will affect the extent of these impacts. Low mass buildings make the impacts of higher temperatures more severe since higher masses are able to absorb heat during the day and then dispel it during cooler periods at night. Other factors are the degree of air-tightness and ventilation patterns. Research on the most appropriate domestic designs for thermal efficiency in hot conditions is ongoing; research conducted in Australia suggests that reverse brick veneer (whereby the brickwork is internal, with insulation and then a rendered fibro-cement exterior) may be the most effective domestic construction method (Gregory et al., 2007) A study of different built forms for housing (Hacker et al., 2005) found that in a typical 19 th century house internal room temperatures would often exceed the hot 9 threshold in the future. In the 1980s only 2% of the occupied hours in the living room and 7% of those in the bedroom would be above this threshold; by 2050 these figures rise to 13% and 18%. The peak temperature in the living room would be 35 o C in the 2050s. For a new build house meeting the 2002 Building Regulations standards, the figures for exceeding the hot threshold in the 1980s were 1% of occupied hours in the living room and 11% in the bedroom. By the 2050s the figures were modelled to reach 7% and a staggering 23%. Peak temperature would be 36 o C. Adaptation is able to reduce these figures to some extent. Providing shading and ventilation to the 19 th century house reduces the exceedences to 6% of occupied hours in the bedroom and 3% in the living room. However, peak temperatures are only reduced by 1 o C. In the new build house, shading, automated ventilation and increasing the thermal mass of the building is more effective. Exceedences are reduced to 2% of occupied hours and peak temperature is down to 27 o C in the living room in 2050s (ibid). Flooding is highly location specific. It is estimated that about 1.7 million homes are currently in flood-plains and the coastal zone is occupied by 10 million people (Kenney et al., 2006, p. iv). National data on the level of development in floodplains 9 Hot was defined as 25 o C in the bedrooms and 28 o C in the living rooms 54

56 indicates that substantial areas of new residential development are exposed to flooding risk. The Land Use Change Database for England shows that at least 9% of the dwellings built in each year from 1996 to 2005 have been in flood risk areas; in 2003 the figure rose as high as 11%. Over this decade alone this amounts to well over 3000 hectares. There is some evidence that government policy encouraging new house building to take place on previously developed land is part of the reason for this pattern. In 2005, 80% of the dwellings built in flood risk areas were on previously developed land. Changing patterns of rainfall will also create drought periods affecting housing in some areas, with reduced water availability and/or rising costs of water supply. This may exacerbate the negative experience of heat waves, since water demand rises during such periods. This is a particular concern in some of the Growth Areas, such as Thames Gateway (Land Use Consultants et al., 2005). The variations in rainfall and reduced soil moisture at certain times of the year also create the potential for ground movement and subsidence. Again, this is a location specific risk. It is likely to affect older properties with shallower foundations. In this context it is relevant to note that 20% of the dwelling stock in England was built before 1919 and a further 19% between 1919 and London has a particularly old housing stock, with 26% built before 1918 and 32% in the interwar period; this is a problem given the underlying London clay. Given current low levels of demolition, 80% of the current stock will still be in existence in 2050, including many of these older properties. However, Sanders and Phillipson (2003) consider that new domestic construction needs to employ deeper foundations than currently used and to consider innovative techniques such as prefabricated strips or pile-and-beam methods, suggesting that even more recent property may be at risk from ground movement. The climate scenarios suggest that increased wind speed is one of the more uncertain risks associated with climate change. Nevertheless there are potentially significant costs associated with damage from higher wind speeds and the roofs of properties built with lower wind loads in mind at greater risk from storm events. 10 DCLG Housing Statistics Table 110; estimated from the 2006/7 Survey of English Housing 55

57 2.2.2 Offices and Business Parks Baseline temperature rises and heat waves will affect office occupiers, leading not just to discomfort but lower work efficiency and loss of work time. There may also be emerging issues of liability to workers adversely affected by working in overheated conditions. This would render buildings which are unable to control internal temperatures less attractive within the market. Alternatively the new temperature conditions will lead to considerably increased demand for artificial cooling in buildings that have not been designed to cope with higher temperatures. Ironically the very temperature conditions that require greater use of air conditioning systems will also increase their failure rate since they are not engineered to operate at such increased temperatures (from 0.5% of the year to 4% by 2080s; DEFRA et al., 2005, p. 43). In this context it is worth noting that 28% of current office floorspace was built before 1940 and 46% before ; 22% and 37% of office rateable values (RV) respectively are in these age categories. Some of these premises may have been adapted and improved but they may still be less suited to the climate conditions of the future. Again the mass of the buildings is a key factor in coping with higher temperatures, whether prolonged or in heat waves. A Study of a typical 1960s office (Hacker et al., 2005) has shown that in the 1980s the internal temperature is over 28 o C for 6% of occupied hours; by the 2050s this has risen to 16%. Peak temperatures on the top floor reach 37 0 C in 2050s. A mixture of adaptation measures (including shading, ventilation and cooling) can substantially improve the situation to remove all incidents of temperatures rising above 28 o C even up to 2080s, although there is an energy and carbon cost to such measures, particularly from the use of mechanical air conditioning. Advanced designs for naturally ventilated office buildings, which do not have exceedences in the hot category during 1980s will, nevertheless, have just under 4% of occupied hours falling in this category by 2050s on average. This average disguises considerable differences between the ground floor (which remains largely comfortable) and the top floor with 8% exceedences in 2050s. Adapting this building, 11 Valuation Office data, Table 2.2; figures for age of stock for all categories are for England and Wales 56

58 by responding to the problem of the low mass roof with a higher mass ceiling on the top floor, keeps temperatures within the comfort zone until 2080s, although there is some need to use artificial cooling in cases when the temperature rises above 25 o C (ibid). Drought periods due to changed rainfall patterns will affect water use within and around offices, in air cooling units, cleaning, sanitation, landscape irrigation, drinking and other uses. Costs of water supply are likely to rise just as demand for a range of these uses is also increasing due to higher internal and external temperatures. Flooding is again a location-specific risk. Given patterns of commercial office development it is likely that the most common flooding risk will be flash-flooding due to urban run-off. However, there are a number of major office developments in harbour-side or river-side locations such as Cardiff - which may find themselves at risk over the longer term. This is a particular concern in London where the cost implications of major flooding due to the overtopping of the Thames Barrier would be considerable. Location and construction method affect the vulnerability of the office sector to ground instability and wind speed risks. Only properties of less robust construction and on clay soils will be at any significant risk Industrial Premises It might be expected that industrial premises will be less vulnerable to temperature rises and heat waves than offices, with their higher concentrations of workers per unit of floorspace. However, some production processes are vulnerable to overheating and will require additional cooling in the future to avoid liability issues and loss of production time. Factories have not been traditionally designed with this in mind, often having low thermal mass. Although only 24% of the factory floorspace comprises properties built before 1940 and 17% of the RV of factories is constituted by these older properties, the figures for properties built before 1971 are 56% of floorspace and 47% of the RV. About a third of the stock comprises post-war properties built before 1971 that are unlikely to be designed to cope well with temperature change. 57

59 Since flooding is a location-specific risk, it will be the industrial premises in areas relatively close to rivers and unprotected coasts that will be most affected, although urban run-off remains a hazard for all properties in urban areas. It is estimated that 40% of manufacturing industry is located within the coastal zone (Kenney et al., 2006, p. iv). The run-off of water during intense rain episodes will be affected by the substantial areas of hard surfacing that typically surround industrial premises. Sustainable urban drainage systems have not traditionally been incorporated in industrial estates to mitigate such risks. Many industrial processes are heavy users of water and these will be particularly affected by drought conditions and future rising costs for water. However, this will not affect all property types. Ground instability is another location-specific risk, but modern industrial sheds (which have dominated the sector for the last fifty years) are likely to be more resilient in the face of flooding given their design. While their construction may be considered to render them more vulnerable to increased winter wind speeds and storm events this would only be the case if the properties were atypically large or tall. Industrial and warehousing typically uses steel-framed construction and piled foundations and should be resilient to subsidence issues Warehouses and Distribution It might be assumed that, given the lower workforce per m 2, temperature is less of an issue in the warehousing and distribution property type than in the other types considered. However, there are a range of categories of goods that may well be affected by higher average temperatures and by the greater frequency of heat waves; these include food and other perishables, electrical equipment and chemicals. The warehousing stock is considerably younger than the office and industrial stock. Only 16% of warehousing floorspace falls into the pre-1940 category and 57% of the total floorspace has been built since 1970; only 10% of warehousing RV is accounted for by pre-1940 premises and 68% by post 1970 premises. This property type is dominated by standard shed constructions which have a low mass and will transmit external heat to interiors very readily. However, as with modern industrial premises, 58

60 they are likely to be able to cope with higher winter wind speeds and storm episodes, and to be relatively resilient to any ground movement. With regard to flooding, warehousing and distribution properties are likely to find themselves in much the same situation as industrial premises regarding this locationspecific risk. The ground-floor design of almost all warehousing will however expose a greater proportion of the operational area to any flooding that occurs. Drought periods and rising water costs are less likely to affect premises in this category. 59

61 2.2.5 Retail Premises The retail sector varies considerably between the large mass of small unit high street properties (and other secondary and tertiary locations), retail parks and the purpose built shopping centre and parks. Overall, the retail sector is surprisingly elderly. 40% of retail floorspace was built before 1940 and 36% of the retail RV is accounted for by these pre-1940 properties; 57% of the floorspace is pre-1971, comprising 49% of total RV. In London, 57% of the floorspace was built before These will mainly constitute the high street locations, contrasting with the more modern purpose built shopping centres. The vulnerability of the retail sector as a whole is therefore rather more difficult to assess. Higher baseline temperatures may encourage more shoppers out to the High Street but heat waves will probably deter them; the multiples may be able to invest in cooling but many smaller shops will not. In heat waves, the climate controlled conditions of shopping centres and malls may be attractive, but only if shoppers can find comfortable ways of reaching them (e.g. air conditioned cars or metro systems). Where air conditioning is used, costs will rise due to higher temperatures although the high mass concrete-based construction of some shopping centres may mitigate some of the need for artificial cooling. The age structure of retail premises may render some of the older properties, particularly high street properties more vulnerable to ground instability (in relevant locations) and higher winter wind speeds. New shopping centres should, however, be built to give them greater resilience in the face of such hazards. Wind may also affect high street shopping areas through reducing the comfort and safety of pedestrians (Sanders and Phillipson, 2003). Exposure to flooding risks depends on the location of the properties, particularly for riverine and coastal flooding. However, the town centre location of much retail property can be assumed to increase its vulnerability to flash-flooding arising from urban run-off in intense rain periods. 60

62 Information suggests that shopping centres use around 3-4 times at much water as offices on an annual basis 12. This renders them more vulnerable to the risks of drought and rising water costs in certain locations. This is less of an issue for the high street property. 2.3 Climate Change Risks and Infrastructure Systems Urban areas do not just comprise a collection of individual properties but are rather characterised by the interconnections of infrastructure systems. The overall vulnerability of urban areas to climate change is highly dependent on how these infrastructure systems cope with changed circumstances. Table 2.2 summarises the climate change impacts on the main infrastructure systems. 12 Personal communication from Upstream. 61

63 Table 2.2 Climate Change Risk Increased temperatures Heat waves Extreme rainfall events Drought periods Reduced soil moisture Increased wind speeds Vulnerability of infrastructure systems to climate change risks Transport Energy Water Sewerage Urban Supply Supply Drainage LOW/MEDIUM LOW LOW LOW LOW HIGH MEDIUM HIGH LOW LOW HIGH HIGH HIGH HIGH HIGH LOW LOW HIGH MEDIUM LOW MEDIUM LOW/MEDIUM LOW MEDIUM LOW MEDIUM MEDIUM LOW LOW LOW 62

64 2.3.1 Transport Infrastructure The increased variability of the weather will make any transport planning more difficult. Individuals will find themselves caught in torrential rain storms or snow storms in their cars; public transport operators will have to cope with sudden changes in weather. However, the greatest impacts of climate change on transport infrastructure are likely to come from heat waves and flooding events (see also Zimmerman, 1999). Heat waves will particularly affect public transport systems, when temperatures may become untenable, particularly in rail and underground rolling stock that has no natural ventilation. However, roads may become vulnerable to heat waves if temperatures cause surfaces to melt; increased incidents of rails buckling will also occur. Flooding could over-run roads and rail networks at multiple locations. In addition, heavy rainfall may increase the risk of landslip affecting both road and rail networks. Coastal networks are clearly at risk, particularly in the south and east. While wind speeds are not predicted to increase with any certainty, more frequent winter storms may lead to key links in the road and rail infrastructure being closed more often. This particularly applies to bridges and to high-sided vehicles such as buses, coaches and freight lorries. Road and rail tunnels, on the other hand, will be vulnerable to disruption from flooding Energy Supply Infrastructure Temperature increases are likely to have less impact on energy supply infrastructure, although overground supply lines may face some problems in heat waves; similarly such supply lines are vulnerable during winter storm events with high winds. Climate change is most likely to impact physically on energy supply through flood events, impacting on key points within the network such as electricity sub-stations. Power stations may also be vulnerable in certain locations; because of their great demand for water, power stations are often located near water sources. It is worth remembering that several of our nuclear power stations are in coastal locations. 63

65 The reliance of many power stations on a water supply can also render them vulnerable to drought conditions. In France during the heat wave of 2004, some of the country s nuclear power stations had to be powered-down because of a shortage of water for cooling. There are, of course, a range of impacts on energy supply arising from the different patterns of energy demand associated with climate change. These are, however, outside the remit of this report Water Supply Infrastructure Although increased baseline temperatures are unlikely to affect water infrastructure directly, water supply will have to cope with increased demand particularly during heat waves (see also Matthias et al., 2007). It has been estimated that by 2050s the impact of climate change on water demand in England and Wales could be % increase (DEFRA et al., 2005). The uneven nature of demand surges will be a particularly difficult management problem. This will be in the context of greater periods of drought in some locations, putting water suppliers in a pinch-point of greater demand for and less availability of water at the same time. Water supply may also be affected by reduced permeability of the ground due to lower soil moisture, affecting the recharge of aquifers and water tables. In coastal areas, sea level rise may result in salt water permeating the water table and affecting its value for water supply. Furthermore, flooding may affect water treatment plants in the same way that key installations in energy supply will be affected. Flooding may also result in pollution (from a variety of sources) and contamination (e.g. by sewage) of water sources, increasing treatment costs. Pipework may be affected by subsidence, while older reservoirs may be under pressure from the increase in water during intense rain events, with the possibility of catastrophic collapse. 64

66 2.3.4 Sewerage Infrastructure Sewerage infrastructure may be vulnerable to flooding from a variety of sources. Treatment plants may be over-run with water, like electricity sub-stations or water treatment plants. This will affect not only the operation of the sewage treatment processes but also run the risk of generating pollution. Given that the urban drainage and sewerage systems in the UK are not completely separated, flooding from urban run-off will also generate more incidents involving sewage pollution of water courses. Investment is needed to rectify this problem, particularly given the age of much of the infrastructure. Subsidence may also affect sewerage pipework Urban Drainage Infrastructure The main concern from the perspective of urban drainage infrastructure is the capacity to cope with urban run-off during intense rain episodes (see also Denault et al., 2002). In coastal locations, this may be exacerbated by tidal surges locking-out urban drainage systems. This requires investment to overcome such problems. An associated concern is that reduced soil moisture will affect the permeability of the soil and exacerbate urban run-off. This highlights the significance of sustainable urban drainage systems in urban areas. 2.4 The Role of Property Insurance The above discussion has emphasised that climate change will impact on all types of property in a variety of ways. Of concern to the UK property sector will be the issue of who bears these risks in the first instance. In many cases it will be occupiers who bear the burden of increased temperatures, increased water costs and/or disruption, flooding and ground movement. However these are likely to be passed on to the insurance sector in many cases and the continued willingness of the insurance sector to bear such costs will shape property markets in the future (Kenney et al., 2006). Higher insurance premiums will feed through to occupiers and then to owners of property. Withdrawal of insurance will have a more significant impact on the rental and capital value of affected property. 65

67 The insurance industry has acknowledged that climate change creates particular problems (e.g. ABI, 2006). This is not just due to the extent of the likely negative impacts but also because of the uncertainty of future impacts; this poses a considerable challenge to setting actuarially sound rates for insurance. Furthermore, while more insurers are using catastrophe models within their modelling, this may fail to capture the large number of smaller adverse events arising from climate change such as localised flooding and soil subsidence; such small weather-related events account for 99% of the annual total (Mills, 2003). In Norway, the government has established the Norwegian Pool of Natural Perils, which settles natural disaster damage compensation between companies and ensures the reinsurance coverage of such natural disaster insurance. This form of risk pooling makes the insurance industry more resilient (Lisø et al., 2003). Other sectors that will bear the burden of climate change risks will be the water companies (and eventually the water company customers and shareholders), the health services, the Environment Agency and local government. The mix of public and private sector bodies involved in responding to climate change impacts means that a concerted approach will be needed to share both the financial costs of the impacts and the costs of investments to mitigate those impacts (e.g. sustainable urban drainage systems to reduce flooding hazards; water storage systems to reduce exposure to drought; flood defences; etc.). 66

68 3. Climate change scenarios for selected UK cities In this section (and section 4), climate change scenarios (table 3.1) for 14 different locations in the United Kingdom (figure 3.1), are presented for the 2020, 2050 and 2080 time-slices. These are: Belfast, Birmingham, Bristol, Cambridge, Cardiff, Edinburgh, Glasgow, Leeds, Liverpool, London, Manchester, Newcastle, Southampton and the Thames Gateway. The climate change scenarios for each location have been obtained by examining the data available for the 50 km x 50 km grid squares in which they are located (scenarios for the Thames Gateway are based on those for Chatham, Kent). All changes in the climatic variables are presented either as differences or percentage changes relative to the modelled baseline climate ( ) which is derived using the IPCC SRES medium-high emissions scenario. Table 3.1. Climatic variables detailed in this report and their definition (source: UKCIP02). Climate variable Unit Definition Summer temperature C Monthly mean summer (JJA) temperature Summer max temperature C Monthly mean maximum summer (JJA) temperature Winter temperature C Monthly mean winter (DJF) temperature Mean precipitation mm Monthly mean annual precipitation rate Summer precipitation mm Monthly mean summer (JJA) precipitation rate Winter precipitation mm Monthly mean winter (DJF) precipitation rate Winter wind speed m/s Wind speed measured in m/s at 10 m elevation Annual soil moisture mm Monthly mean soil moisture in the root zone Summer soil moisture mm Monthly mean summer (JJA) soil moisture in the root zone 67

69 Figure 3.1. Map of the UK highlighting the locations investigated. As stated in the text, the scenarios for the Thames Gateway have been derived from those for Chatham, Kent. As already discussed, the UKCIP02 temperature projections for the United Kingdom are based on rural land-cover within individual grid squares and do not take into account the urban fabric and anthropogenic heat sources (e.g. air conditioning and transport). Consequently temperature increases in UK cities are likely to be higher than the values given in this section. For example the modelled baseline mean maximum summer temperature for the grid square in which Manchester is located is 17.3 C, however the observed mean maximum summer temperature at Manchester Airport for the same period was 19.1 C 68