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Urban Heat Islands. An urban heat island is a metropolitan area which is significantly warmer than its surrounding rural areas. Bare earth and vegetation. Water. Albedo. Buildings and the Ground Store Heat. Sources of Heat. Cityscapes v landscapes. Energy in and out. London, 2000.
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Urban Heat Islands An urban heat island is a metropolitan area which is significantly warmer than its surrounding rural areas.
London, 2000 Richmond Park British Museum
London, Summer 2000 sunset Sunrise
The urban heat island is biggest… • At night (before sunrise) • In the summer • When there is no wind • When the sky is clear • When the weather doesn’t change through the night
Excess mortality rates in early August 2003 indicate about 40,000 heat-related deaths Daily mortality in Baden-Württemberg
observations HadCM3 Medium-High 2050s 2003 Temperature anomaly (wrt 1961-90) °C European 2003 summer temperatures “Right now, we average about 14 days each summer above 90 degrees in New York. In a couple of decades, we could be experiencing 30 days or more,”
What’s that got to do with the UHI? • London – 600 heat related deaths in August 2003 • Up to 9 °C warmer than surrounding rural areas • Mortality increases with temperature when temperatures are over 22°C • Mortality particularly linked to warm night time temperatures • Mortality linked to age, sex, deprivation etc. • Challenge now to design buildings and urban areas for the future – which will see more people living in cities, and will be warmer.
Other Consequences • The growing season can be up to 15 days longer in a city! • Warmer in a city in winter • Rainfall