Though Manhattan experiences similar daytime temperatures to surrounding areas, it simply doesn't cool off nearly as much at night. Photo: Jakob Montrasio via flickr.
If you thought the heatwaves we've already experienced this summer in New York City and all along the East Coast were bad, there's definitely more sweating in your future. A new study coming out the City College of New York shows that continued warming temperatures, combined with the well-known (and growing) urban heat island effect, means more frequent and more intense heatwaves are in store for New York. New York City Nights 15 Degrees Warmer Than Surrounding Areas
Illustrating the amplifying effect of the urban heat island on recent heatwaves, according to data collected by CCNY's New York City Meteorological Network, during the first July heatwave overnight temperatures were 10-15°F higher in Manhattan than on Long Island or in western New Jersey, just a few miles away. Daytime highs were similar throughout the region.
Professor Jorge Gonzalez reminds us (as if New Yorkers needed reminding of this), "While surrounding suburban and green areas may perceive the same maximum temperatures, the built regions will perceive them for longer periods of time."
Urban Pollution Also Affects Rainfall Patterns Near City
But where the research gets really interesting is when it examines the effects of pollution from the city on weather:
Urban areas tend to generate aerosols, and the resulting humidity could modify precipitation patterns by interacting with clouds and affecting the energy balance, Professor Gonzalez explained. "The presence of pollution could increase or diminish rainfall. It could change the frequency and severity of storms, as well."
Split storms, like the ones that deluged some Long Island communities earlier this month while leaving neighboring villages dry, could also be a phenomenon influenced by cities. "Because of heat and aerosols, cities could play a role by acting as a barrier to storm fronts, resulting in very concentrated storms in scattered areas." (Science Codex)
Aerosols Have Effect On Climate As Well As Weather
Aerosols, fine particles of solids or liquids in the atmosphere, also have a direct effect on global warming. Some decrease warming by reducing the amount of the sun's radiation--some of those from coal-burning power plants fall into this category, canceling out some of the warming caused by their other emissions--while others, soot in particular, have a marked effect increasing warming.
Better Urban Planning, Building Design Helps
Gonzalez goes on to note that efforts to green the City through more urban parks and green spaces--tragically, some of which the City wants to remove--vegetated roofs, as well as lightly-colored roofs, will mitigate some of the urban heat island effect. Which is something that TreeHugger and plenty of green-minded urban planners have been saying for some time...
It's worth noting, even if Prof Gonzalez doesn't, that it doesn't help that to cope with the increased heat, both day and night, ubiquitous air conditioning blasts onto the streets and into the air, causing further experienced warming, as well as using increased amounts of energy leading to further climatic warming.
Somewhere the cycle has to break, though a combination of better designed buildings that keep naturally cool without added outside energy inputs, as well as individuals simply adapting to higher normal temperatures (even if that's uncomfortable in the short term).
More on Global Warming Effects:
The Link Between Record-Breaking Global Heatwaves and Climate Change
Global Warming Could Double Heat Fatalities Within 50 Years
5.2°C Temperature Rise by 2100: New Business-As-Usual Climate Scenario Presented