Article from Green Futures Magazine – May / June 2003
www.greenfutures.org.uk
Worldwide, more and more of us live in larger and larger cities. Francesco Corsi draws some lessons from Entec's work on climate change and the urban condition.
How often do we stop to consider what climate change will
really mean for our everyday lives? City-dwellers are likely to find much of
interest in a recent Entec-led study, London's Warming , commissioned by the
London Climate Change Partnership. It focused on several different scenarios,
and although it worked through them in the context of their implications for
London in particular, there are real lessons there for large cities everywhere.
While climate change is generally accepted to equate to higher average temperatures
all around, this is a particularly sensitive issue for cities because of the
urban heat island effect - the phenomenon of a city being several degrees hotter
at its centre than at its edges, principally because of heat emitted from buildings
and the characteristics of airflow. When modelled for central London, it is
estimated that we are looking at an extra 5-6C on summer night temperatures
- a striking difference, with detrimental impact on air quality, summer electricity
demand, and comfort in the city's buildings and transport network. By the 2080s,
London's summer extreme temperatures could be comparable with those of present-day
New York - while New York's could be in a different league again.
Then there's the relationship between climate change and flooding - a matter of relevance for most major cities, especially since so many have important rivers flowing through them, as well as a greater concentration of valuable (and vulnerable) assets than smaller urban and rural areas. If climate change increases the likelihood and frequency of flooding events, as it is expected to do, the implications for city life are serious. Last year's floods in Prague, Dresden and other European cities bear testament to what can happen without adequate defences. London is by far the most exposed of all the UK's cities, due to the combination of its high asset values, and the fact that a significant proportion of the city lies within the floodplain of the Thames and its tributaries. Although its current flood protection is very good, and the Thames Barrier serves its purpose in counteracting tidal surges, the city will have to face up to the likelihood of further investment to avoid damage to buildings and disruption to the transport network in future.
Water resource demands in larger cities are already under pressure in many parts of the world. Londoners use more water than the national average, but person for person they have the UK's lowest available resources. Factor in climate change, and you are looking at less water - and more summer peak demand.
And air pollution? Already unacceptably bad in most of the world's largest cities, it gets worse at certain times of year and under certain weather conditions, such as still, sunny summer days - one kind of weather we can expect more often, especially if we're getting the predictions right about changes to prevailing winds. Increased street-level air pollution would raise the frequency of serious health problems, damage to buildings and urban plantlife.
A great deal to be concerned over, then - but some positive prospects too.
In the UK, who's for
more outdoor living, pavement cafés, music, theatre and alfresco dining
if the weather's warmer? And would a warmer London seem more attractive to
tourists, and southern European destinations less so? This isn't the flippant
point that it might seem at first sight, if planning the shape of our cities
in the 21st century and beyond is to take account of all the impacts of climate
change. But the severity of that change over the coming century is neither
certain, nor inevitable - and our actions, and inactions, will help determine
that too.
Francesco Corsi is marketing manager at Entec UK
London's Warming can be downloaded from the UK Climate Change Impacts Programme
(www.ukcip.org.uk), and is also available at www.london.gov.uk.
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