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

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.
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.
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.