Climate Change and Cities || Climate Change and Cities

Climate Change and CitiesAuthor(s): DARRYN McEVOYSource: Built Environment (1978-), Vol. 33, No. 1, Climate Change and Cities (2007), pp. 4-9Published by: Alexandrine PressStable URL: http://www.jstor.org/stable/23289469 .

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BUILT ENVIRONMENT VOL 33 NO 1



Climate Change and Cities

DARRYN McEVOY

Climate change is considered by many as one of the greatest threats facing societies over the coming decades. With increasing scientific consensus that climate change is

being enhanced by human activity (IPCC, 2001), the issue has risen rapidly to the top of both research and policy agendas, and is now the subject of widespread media

coverage and increasing public concern.1

Although often labelled an environmental

issue, it is increasingly recognized that climate change has important social and economic dimensions as well. The focus of this special issue is on climate change and its

implications for UK towns and cities, where most people live and work, and where the

impacts of a changing climate will be most

keenly felt. To date, research has tended to focus on

understanding what the potential climate

related impacts are likely to be, and the

challenge of reducing anthropogenic green house gas emissions through mitigation activity. However, even if we are successful

in reducing our emissions, societies will still need to adapt to some level of climate change - because much of the change that will occur

in the first half of this century has already been pre-determined by past and present emissions of greenhouse gases (Hulme et

al, 2002). As a result, there is increasing

recognition that a wider response to climate

change is needed, highlighted by the shift

towards risk-based approaches and the

identification of processes and mechanisms for adapting to climate change (see for ex

ample, Willows and Connell, 2003; Lindley et al., 2006; World Bank, 2006).

Although uncertainties about future

climate change exist, both in the magnitude of future greenhouse gas emissions and in modelling the complex climate system, recent scientific advances have allowed scenarios to be developed at a scale suitable

for investigating future regional climates and

impacts. For example, the UKCIP02 scenarios,

developed by the Hadley Centre for Climate

Change and the Tyndall Centre for Climate

Change Research for the UK Climate Impacts Programme (UKCIP), are the most up to date, detailed and reliable scenarios available in the UK (Hulme et al, 2002). The UKCIP02 scenarios report is widely referenced. The

underlying data are used to support ongoing research into climate change im-pacts and

adaptation options, ultimately contributing to better informed decision-making across a wide range of sectors (for example, for

the tourism sector, see: McEvoy et al., submitted). UKCIP have also developed an

accompanying portfolio of tools, including a framework to support decision-making under

conditions of risk and uncertainty (Willows and Connell, 2003).

The UKCIP02 scenarios indicate that

changes to our climate will start to become

evident by the 2050s, with significant changes occurring by the 2080s. These time scales are seldom in the direct vision of most policy makers: even regional spatial strategies, for

example, which are charged with considering longer-term spatial planning issues in England, currently deal with forward horizons of only 15-20 years. However, it is increasingly recognized that we need to prepare for the

longer-term consequences of climate change.

This is particularly acute for the urban environment as much of the infrastructure




CLIMATE CHANGE AND CITIES

is designed and built to last for long periods of time and we need to act now to ensure

that buildings, infrastructure and open space are adequately 'climate proofed' for future conditions.2 It is also recognized that, due to

the slow turnover of urban stock, retrofitting

is likely to be necessary in many instances

(McEvoy and Lindley, 2006). Therefore, a

major challenge for policy-makers will be to ensure that climate change considerations

(both mitigation and adaptation3) are fully integrated within spatial planning and

development control (McEvoy et al., 2006). The first paper in this special issue on

climate change and cities considers the latest thinking on the use of climate change scenarios and decision-making under un

certainty. Clare Goodess and her co-authors

first summarize the uncertainties inherent in climate change scenarios, before elaborating on the next generation of UKCIP scenarios, due for release in 2007, which will adopt a probabilistic approach for the first time.

They then describe the development of novel methods which can be used to promote

decision-making under uncertainty, such as

the imprecise probability and information

gap method, before presenting examples applied to specific problems in the built environment.

Scientific evidence has shown that risks to the built environment in the UK will be driven primarily by increased temperatures, changing precipitation patterns (more rainfall in winter, less in summer), an increase in the frequency of extreme events, with the

possibility of more storms (Graves and

Phillipson, 2000; Hulme et al., 2002; LCCP,

2002). Coastal towns may also be subject to

rising sea levels combined with storm surges. Although the overall magnitude of change is

important, serving as a measure of climate

change against which to compare sensitivities and impacts, other variables such as climate

variability (including extreme events) and rate of change are equally important (IPCC, 2001). All systems have some capacity for

self-adjustment (autonomous adaptation)

but it is recognized that the likely pace and intensity of climate change is such that planned adaptation will be needed to reduce vulnerability. As Defra note in their

Adaptation Policy Framework document

'adaptation to cope with more frequent weather extremes and planning for the longer term changes needs to begin now' (Defra, 2005, p. 26). However, climate change is not the only driver affecting future risk. Others include changes to land use and urban form

(for example, policies promoting densification

etc.), lifestyles, and socio-economic trends. These different drivers do not act in isolation; rather they tend to interact with each other. For example, both climate change and urban

form are partly dependent upon lifestyle choices, while climatic changes themselves

may facilitate, inhibit or accentuate lifestyle choices (Gill et al., 2004). The complicated interactions between climate-related hazards

and other urbanization processes can either

amplify or moderate impacts on the built environment.

The second paper in this special issue

by Rob Wilby collates evidence of the key impacts, and reviews what the changes may mean for the built environment. The impacts are framed using the 'checklist for developers' format developed by the Greater London

Authority, addressing issues of ventilation and cooling, urban drainage and flood risk, water resources supply, and outdoor spaces. In his paper, Wilby suggests that higher resolution analysis of impacts is needed in order to improve our preparedness and to

safeguard human health and comfort against climatic hazards, and concludes that effective

'joined-up' decision-making will require more

sharing of information with practitioners (i.e. that enhancing knowledge transfer between the scientific community and the 'users' of climate change information is integral to informed decision-making), as well as better

integration of adaptation measures 'across' sectors.

Reinforcing this thinking, the third paper by Sarah Lindley and her co-authors argue





that a coherent adaptation response to

climate change impacts needs to be based on

a greater understanding of the risks involved.

The authors detail a spatial risk assessment

methodology for the urban environment

that has been developed for this purpose (focusing on heat stress as an example). Acknowledging that spatial planning has a

key role to play both in terms of planning for extreme events (emergency planning) and longer-term changes (strategic planning and urban design) the authors also critically assess the role of the planning system in

managing climate-related risk. This special issue then addresses two

specific climate-related hazards facing the urban environment in detail, flooding and heat stress. In terms of the former, winter

runoff in the UK is likely to increase and summer runoff decrease, with analysis of

extreme events also suggesting that there

will be an increase in the frequency of both high and low flow events (Pilling and

Jones, 1999; Hall et al., 2005). However, individual catchments vary significantly: riverine flooding is location specific and

modelling of specific river catchments is

necessary to address how particular rivers

respond to changing rainfall patterns (CURE and Tyndall Centre, 2003). Further complexity is added when trying to assess and manage flood risk within the urban environment. In

particular, a major contemporary driver of

urban flooding in the UK is densification (and the increasing impermeability of surfaces), with development being encouraged within the confines of existing urban areas and on

previously developed land (ODPM PPG3 and draft PPS3) in order to counter urban extensification. Although consolidation is central to the Urban Renaissance agenda (DETR, 1999) the loss of permeable spaces through urban 'creep' (for example, the

conversion of gardens for car parking) is

likely to have significant implications for urban flooding (Duckworth, 2005). Climate

change will act to further exacerbate this flood risk in the future. Addressing the

issues of changing precipitation regimes, building drainage and urbanization, the

paper by Richard Ashley and his co-authors focuses on localized flood risk management from an urban perspective. Their work

highlights the complexity associated with

adapting to climate change, particularly the need to account for uncertainty in any

response. Taking a case study approach, the authors emphasize that an effective response will need to involve a range of different stakeholders and ideally should promote dispersed 'adaptable solutions' rather than robust but inflexible approaches which aim for a 'big fix' solution. This suggests a move away from merely considering 'hard' engineering solutions towards wider

approaches which also take account of

aspects of lifestyle, degree of risk aversion, urbanization trends etc. For example, the

authors suggest that there is a need to

develop a better understanding of mixed

impervious and pervious surfaces within the built environment.

In relation to temperature, it has long been

recognized that cities are typically warmer than adjacent rural areas. Their distinctive

microclimate, often several degrees warmer

than the surrounding countryside, is caused

by differences between energy gains and

losses. This phenomenon, a combined result of

urban physical attributes and anthro-pogenic activity, is known as the Urban Heat Island effect (UHI) (Graves et al., 2001; Wilby, 2003). The most marked effect is during the night when rural areas cool more than urban areas.

Although there are some benefits associated

with the UHI, such as more comfortable

evening temperatures, negative impacts are considered much more significant. Important direct impacts include heat stress (as critical

temperatures are surpassed), evidenced by the tens of thousands of additional deaths that occurred in urban areas across Europe

during the heat wave of 2003 (Larsen, 2003). For this special issue, Richard Watkins, John Palmer and Maria Kolokotroni examine the

consequences of higher air temperatures





for the urban environment, focusing on the

implications for health and human comfort. Their paper also highlights that the precise impact on UHI of future changes to climate and urban form remains uncertain. For

instance, higher temperatures are likely to lead to an increased use of air conditioning, which in turn will lead to more urban waste

heat, resulting in an intensification of the UHI effect. That said, the authors contend that a

range of design opportunities is available to improve human comfort in the urban

environment, with adaptation of the urban

environment simultaneously contributing to other 'quality of life' objectives. The heat theme is continued by Jake Hacker and Michael Holmes in their paper which addresses overheating in buildings during higher summer temperatures. Although air conditioning is increasingly the routine

adaptation option, it currently leads to increased C02 emissions and a consequent reinforcement of the climate change problem. Here, the authors focus on the potential for

alternative 'passive' adaptation options, analysing the contribution of different vari ables (such as direct cooling ventilation,

shading, regulation of daytime ventilation, and use of thermal mass) to a summertime

overheating strategy, and how this strategy may be influenced by climate change in the future.

The creative use of green infrastructure in

cities (soft engineering) is cited by Susannah Gill and her co-authors as one of the most

promising opportunities for adaptation. Al

though not a panacea, the multifunctional attributes of greenspaces are extremely im

portant for the ecological performance of our towns and cities. As well as benefiting microclimate and contributing to human

comfort, urban greenspaces reduce storm

water runoff, as well as providing floodwater

storage. They also provide habitats for plants and animals in the urban environment, and can serve as wildlife corridors to maintain local habitats and potentially allow species to move to new climate spaces (Whitford et ah,

2001). Furthermore, the authors argue that it

is critical that decision-makers acknowledge the importance of soft engineering to a greater extent, and have a better understanding of the ecosystem functions provided by open spaces, green and blue infrastructure,

sustainable drainage systems (SUDS) etc. To illustrate this, the environmental functions of

greenspace (both in terms of energy exchange and surface water runoff) are quantified in order to explore its adaptive potential. The authors argue that greenspace provides vital

ecosystem services which will become even

more valuable under climate change, and

they stress that the importance of this critical natural capital needs to be recognized by planning at all spatial scales.

As is evident from the content of this

special issue, climate change is a complex and cross-cutting issue. Drawn from a

range of academic disciplines and based on the latest scientific knowledge, the issue addresses what it means for the urban en

vironment in terms of impacts, risk assess

ment, adaptation, and decision-making under uncertainty. Although the papers are

based on the latest research in the UK, the

discussions and findings are intended to have wider resonance. Making this information available to the 'user' community through

publications such as Built Environment can make a valuable contribution to increasing

society's capacity to adapt to climate change and extreme events in the future. We all have

a role to play in securing a sustainable future -

adapting to climate change will be critical in

maintaining, even enhancing, quality of life in our towns and cities.

NOTES

1. For example, a poll for BBC World Service

covering nineteen nations was undertaken earlier

in 2006. Ninety per cent of those questioned from

Great Britain were concerned that energy use

was harming the environment by contributing to

climate change.

2. Building Knowledge for a Changing Climate





(BKCC), funded by the Engineering and Physical Sciences Research Council in collaboration with

UKCIP, was a research programme designed to

address this agenda (http://www.ukcip.org.uk/

resources/sector/projectsdets.asp?sector=l&pr

oject_ref=5). A follow-up initiative building on

the progress made is Sustaining Knowledge for a

Changing Climate (http://www.k4cc.org/).

3. A new integrated project funded by the

European Commission, ADAM (Adaptation and

Mitigation Strategies), is intended to support climate change policy development across

Europe (http://www.adamproject.eu/).

REFERENCES

CURE and Tyndall Centre (2003) Spatial Implications

of Climate Change for the North West Region of

England. Report for the Northwest Regional

Assembly. Manchester: CURE, University of

Manchester.

Defra (Department for Environment, Food and

Rural Affairs) (2005) Adaptation Policy Framezvork - A Consultation by Defra. London: Defra.

DETR (Department of the Environment, Transport and the Regions) (1999) Towards an Urban

Renaissance. London: DETR

Duckworth, C. (2005) Assessment of urban creep rates for house types in Keighley and the

capacity for future urban creep. Unpublished MA thesis, University of Manchester.

Gill, S. et al. (2004) Literature Review: Impacts of Climate Change on Urban Environments. Man

chester: CURE, University of Manchester.

Graves, H.M. and Phillipson, M.C. (2000) Potential

Implications of Climate Change in the Built

Environment. East Kilbride: BRE.

Graves, H.M., Watkins, R., Westbury, P. and

Littlefair, R (2001) Cooling Buildings in London:

Overcoming the Heat Island. London: CRC Ltd.

Hall, J.W., Sayers, RB. and Dawson, R.J. (2005) National-scale assessment of current and

future flood risk in England and Wales. Natural

Hazards, 36, pp. 147-164.

Hulme, M., Jenkins, G.J., Lu, X., Turnpenny, J.R.,

Mitchell, T.D., Jones, R.G., Lowe, J., Murphy, J.M., Hassell, D., Boorman, P., McDonald, R.

and Hill, S. (2002) Climate Change Scenarios

for the United Kingdom: the UKCIP02 Scientific Report. Oxford: United Kingdom Climate

Impacts Programme.

IPCC (2001) Climate Change 2001: The Scientific Basis. Geneva: InterGovernmental Panel on

Climate Change.

Larsen, J. (2003) Record Heat Wave in Europe takes

35,000 Lives. Washington DC: Earth Policy Institute.

LCCP (2002) London's Warming: The Impacts of Climate Change on London. London: London

Climate Change Partnership.

Lindley, S.J., Hand ley, J.F., Theuray, N., Peet, E.

and McEvoy, D. (2006) Adaptation Strategies for Climate Change in the Urban Environment -

assessing climate change related risk in UK

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McEvoy, D. and Lindley, S. (2006) Adaptive

Management and Climate Conscious Design of Urban Neighbourhoods. Report of the ASCCUE

workshop. Manchester: CURE, University of

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McEvoy, D., Lindley, S. and Handley, J. (2006)

Adaptation and mitigation in urban areas:

synergies and conflicts Proceedings of the

Institution of Civil Engineers, Municipal Engineer, 159, No. 4,185-191.

McEvoy, D., Cavan, G., Handley, J., McMorrow,

J. and Lindley, S. (submitted) Changes to

climate and visitor behaviour: implications for

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Whitford, V., Ennos, A.R. and Handley, J.F. (2001)

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World Bank (2006) Managing Climate Risk: Integrating Adaptation into World Bank Group

Operations. Washington DC: World Bank.




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Climate Change and Cities || Climate Change and Cities