SWELTERING CITY: New models suggest that climate change will cause average temperatures in cities to rise; cooler nights will become less frequent.
Image: ISTOCKPHOTO
Cities were already known to retain more heat than the rural environments that surround them, but new modeling from researchers in the United Kingdom now suggests that urban areas are also more sensitive to changes in climate. Furthermore, they will experience greater increases in average temperature with rises in atmospheric carbon dioxide, and the cooling effects of night will become more of a memory than a reality.
Meanwhile, Washington, D.C. -- where Congress is debating over whether to pass a climate bill -- is getting a memorable preview of what new computer models are predicting. Last week's temperatures broke a 100-year record, and forecasters expect this June will be the hottest ever recorded in the area.
"We're getting a dramatic taste of the kind of weather we are on course to bequeath to our grandchildren," said Tom Peterson, chief climate scientist for the National Oceanic and Atmospheric Administration's National Climatic Data Center.
Urban areas produce their own environments. Vegetation is replaced with steel and Concrete. A natural breeze is reconfigured by skyscrapers and other tall buildings. Soil is covered with black asphalt and loaded with automobiles.
Each transformation contributes something more to what is known as the urban heat island, or UHI, effect, a phenomenon scientists have known about for almost 200 years.
Instead of being consumed by plants or transported away by soil moisture, much of the daytime heat directed into urban areas is absorbed by hard, impermeable surfaces that have no other way of releasing their stored heat except to re-radiate it at night. This gives residents of urban areas little relief from the summer heat long after the sun sets.
In New York City, evening air temperatures can be up to 14 degrees Fahrenheit warmer than those of rural areas that lie within roughly 60 miles, according to a study published by American Meteorological Society in 2009.
Feeling a rise of 5 degrees by 2050
This stored heat will only get worse with increased atmospheric carbon dioxide, said Mark McCarthy, lead author and a research scientist with the Climate Impacts team at the Met Office, the United Kingdom's weather service. The analysis, published in Geophysical Research Letters, was co-authored with Met Office colleagues Richard Betts, head of Climate Impacts, and Martin Best.
The research found that "urban areas are warming faster" than rural ones, in response to rising levels of carbon dioxide, said McCarthy. Their models predict that urban daytime temperatures will rise by more than 5 degrees Fahrenheit in most parts of the world when carbon dioxide levels in the atmosphere reach 645 parts per million, a figure possible as early as 2050.
Nighttime temperatures will also rise by similar numbers. However, in the Middle East, where the UHI effect is the most extreme, cities throughout the region could feel an additional 5 degrees at night.
Besides the Middle East, some of the regions whose local climate is most sensitive to urbanization, including central Asia and western Africa, are also expected to double or even triple in population by 2050, according to U.N. estimates. By that time, more than 68 percent of the world's population will reside within urban areas -- up from 50 percent in 2009.
These trends in temperature and population migration, McCarthy said, are sure to have significant consequences for human health by raising the possibility of heat-related fatalities. According to the U.S. Global Change Research Program, winter cold snaps raise death rates by 1.6 percent, while heat waves are far more lethal, pushing death rates up by 5.7 percent.
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6 Comments
Add CommentAs long as we have un-scientific politicians, like Sen. Inhofe, in positions of power nothing will be done, until it is too late.
Reply | Report Abuse | Link to thisI for one am looking forward to the decrease in the out-of-control human population. Breed like rats, die like rats. In this case, humanity will get precisely what it has been asking for. Perhaps the survivors will learn from the stupidity of the many.
Reply | Report Abuse | Link to thisOr perhaps not. Don't really care anymore.
Modern and huge cities like New York, Los Angeles can't struggle with local warming because of many people live in. People need in electricity hot water and sun rays warm building and roads. Only way to solve this problem to built more and more power stations or destroy skyscrapers and live and work in small wood low buildings.
Reply | Report Abuse | Link to thisLarger cities (most notably LA) are known to have their own local atmosphere (pollution). Are CO2 and other GHGs locally dense enough in these areas to produce verifiable Greenhouse Effects? It would seem that these studies could be useful in resolving the CO2 question (you know, for the 'deniers', of course, or is it the 'believers'? I forget/don't care).
Reply | Report Abuse | Link to thisI agree with hotblack: continued population growth, migration to cities occupying much of the best farmland, overharvesting seafood, contaminating groundwater, etc., hasn't been working out too well for us, has it? We can all just move to the suburbs. Maybe it just starts with road rage...
What, no AGW denier posted nonsense yet? I'm surprised. Usually the first three posts are all "Meh, it's a hoax!"
Reply | Report Abuse | Link to thisMEH, it's a hoax! The same scientist who wanted to launch spaceships with mirrors to reflect more heat to the earth to prevent the upcoming iceage in the 1970's is now BHO's science advisor pushing this climate hoax. The bigger problem is the hole in the gulf and this administrations failure to react.
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