Floods, heat, migration: How extreme weather will transform cities

By George Webster, for CNN

Updated 1321 GMT (2121 HKT) April 4, 2012

Brooklyn Bridge stands shrouded in heavy rain and dark clouds as Hurricane Irene reaches the New York City area on August 28, 2011. According to Jan Corfee-Morlot, senior climate change analyst for the OECD, many developed coastal cities around the world face a "severe risk" of floods in the coming years.
Photos: How will cities adapt to climate change?
Coastal city calamities – Brooklyn Bridge stands shrouded in heavy rain and dark clouds as Hurricane Irene reaches the New York City area on August 28, 2011. According to Jan Corfee-Morlot, senior climate change analyst for the OECD, many developed coastal cities around the world face a "severe risk" of floods in the coming years.
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Russians walk near the Kremlin on Red Square under clear blue skies during a rare heat wave in Moscow, in August, 2010. According to a new report from the UK's Met Office, man-made climate change is likely to cause a global temperature rise of around 3-5C over the next century, and significantly increase instances of freak weather events.
Photos: How will cities adapt to climate change?
Red hot in Russia – Russians walk near the Kremlin on Red Square under clear blue skies during a rare heat wave in Moscow, in August, 2010. According to a new report from the UK's Met Office, man-made climate change is likely to cause a global temperature rise of around 3-5C over the next century, and significantly increase instances of freak weather events.
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Before London authorities built the Thames barrier, the city was prone to floods in times of high tide, as illustrated in this scene from 1963. But, according to Dr Doug Crawford-Brown, executive director at Cambridge University's Centre for Climate Mitigation Research, England's capital may face a return to its deluged days, if extreme rainfall patterns overwhelm current drainage systems.
Photos: How will cities adapt to climate change?
London: The submerged city? – Before London authorities built the Thames barrier, the city was prone to floods in times of high tide, as illustrated in this scene from 1963. But, according to Dr Doug Crawford-Brown, executive director at Cambridge University's Centre for Climate Mitigation Research, England's capital may face a return to its deluged days, if extreme rainfall patterns overwhelm current drainage systems.
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In 2007 the giant Maeslant surge barrier that guards the entrance to the largest port in Europe, Rotterdam closed for the first time since its construction in the 1990s. According to Jan Corfee-Morlot, other coastal cities such as New York and Miami will soon require similar defences.
Photos: How will cities adapt to climate change?
Coastlines to close against climate – In 2007 the giant Maeslant surge barrier that guards the entrance to the largest port in Europe, Rotterdam closed for the first time since its construction in the 1990s. According to Jan Corfee-Morlot, other coastal cities such as New York and Miami will soon require similar defences.
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A crowded row of skyscrapers are reflected on a man-made lake while a dark cloud hovers in Singapore. Matthew Kahn, economics professor at the UCLA's Environment Institute, says that this type of high-rise, high-density urban living will be the norm in years to come, as cities adapt to migrants escaping their climate-ravaged homes.
Photos: How will cities adapt to climate change?
The skyscraper solution – A crowded row of skyscrapers are reflected on a man-made lake while a dark cloud hovers in Singapore. Matthew Kahn, economics professor at the UCLA's Environment Institute, says that this type of high-rise, high-density urban living will be the norm in years to come, as cities adapt to migrants escaping their climate-ravaged homes.
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A newly restored stream flows through high-rise buildings in the center of Seoul in September 2005. The city revived the 5.8 kilometer (3.5 mile) stretch of the stream, which was buried under concrete for decades during South Korea's headlong scramble for economic development. Simon Reddy from the C40 Cities network says the river will help create a "wind corridor" to keep the city cool as temperatures rise.
Photos: How will cities adapt to climate change?
Seoul's windy waterways – A newly restored stream flows through high-rise buildings in the center of Seoul in September 2005. The city revived the 5.8 kilometer (3.5 mile) stretch of the stream, which was buried under concrete for decades during South Korea's headlong scramble for economic development. Simon Reddy from the C40 Cities network says the river will help create a "wind corridor" to keep the city cool as temperatures rise.
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Participants plant rice on the Roppongi Hills' rooftop rice field, in Tokyo on May 17, 2008. Around 130 participated in the rice planting event, held on the top of the building, which was built for environmental education purposes, and also helps to keep down electricity usage as the garden on the roof helps to insulate the structure in summer.
Photos: How will cities adapt to climate change?
Rooftop rice: A meal and an eco-solution – Participants plant rice on the Roppongi Hills' rooftop rice field, in Tokyo on May 17, 2008. Around 130 participated in the rice planting event, held on the top of the building, which was built for environmental education purposes, and also helps to keep down electricity usage as the garden on the roof helps to insulate the structure in summer.
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Bangladeshi pedestrians holding umbrellas hitch a ride on a rickshaw van as they attempt to stay dry over flood waters in the Bangladeshi capital of Dhaka on July 28, 2009. The Met Office study predicts that, over the course of the century, an additional five million people in Bangladesh will be displaced by floods caused by climate change.
Photos: How will cities adapt to climate change?
Downpour in Dhaka – Bangladeshi pedestrians holding umbrellas hitch a ride on a rickshaw van as they attempt to stay dry over flood waters in the Bangladeshi capital of Dhaka on July 28, 2009. The Met Office study predicts that, over the course of the century, an additional five million people in Bangladesh will be displaced by floods caused by climate change.
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Story highlights

  • Tropical storm in Philippines comes just after report on climate change predicts floods
  • Climate change refugees are catalyst to urbanization, stretching city capacity
  • Climate scientists predict how effects of climate change will impact city
  • Floods, droughts, and "urban heat islands" among common characteristics
When Tropical Storm Washi ripped through the southern Philippine city of Cagayan de Oro last weekend, it dumped in one day more than the city's entire average rainfall for the month of December.
According to the Philippine Atmospheric, Geophysical and Astronomical Services Administration, a total of 181 millimeters of rainfall was recorded in the area last Friday, compared to the expected 99.9 millimeters for the whole month.
The devastating flash floods, which have so far claimed the lives of more than 1,000 people, arrived just weeks after a report from the UK's Met Office Hadley Centre for Climate Change indicated that global warming has significantly increased the number of people at risk from flooding.
The report, "Climate: Observations, projections and impacts," examined how climate change will modify the weather in 24 countries around the world.
While findings vary from region to region, it forecasts an overall increase this century of coastal and river floods, extreme weather events and a global temperature rise of between 3-5C, if emissions are left unchecked.
According to climate change experts, cities from New York in the U.S. to Dhaka in Bangladesh are likely to be heavily affected.
Migration
Simon Reddy, executive director of the C40 Cities network, which promotes sustainable development among local city authorities around the world, says this could be a catalyst for migration into urban areas.
"If the forecast temperature rise is accurate, then entire countries could be irrevocably damaged in certain parts of the world -- and their inhabitants will have to find somewhere else to live," he said.
To illustrate his point, Reddy says that a third of flood-prone Bangladesh, in South Asia, could be made uninhabitable by a two-foot (60 cm) rise in regional sea-levels.
The Met Office report echoes this point, predicting that climate change will subject an additional five million people in Bangladesh to floods, if they continue to live in the same place.
"Where are they going to go?" asks Reddy. "In most cases they'll move to where the opportunities and the jobs are -- the nearest habitable city."
With 70% of the world's population expected to live in cities by 2050, according to figures from the U.N., the impact of climate change on the urban environment appears more pressing than ever before.
Floods
Historically, cities built up around water highways and coastal regions have flourished due to their association with maritime trade and transport, said Jan Corfee-Morlot, senior climate change analyst for the OECD.
"This means that a disproportionately high number of the world's cities are located in areas that are now increasingly at risk of floods," she added.
According to Morlot, recent risk studies from the OECD as well as the newly published data from the Met Office report predict that extreme "once-in-a-lifetime" weather events such as flash floods and coastal hurricanes are going to become significantly more commonplace.