Urban impacts on climate - The Global Climate System: Patterns, Processes, and Teleconnections - page 247

In parts of Los Angeles (USA), cool community strategies have been introduced
to provide a more comfortable climate for residents (McKendry 2003 ). Rooftops
and flat areas have been covered with lighter colors, enhancing the albedo and
reducing absorption. Trees have been planted to enhance shading. Model results
for Los Angeles indicate that if these simple measures were adopted for the whole
city, the UHI could be reduced by 3 8C, ozone exceedences reduced by 12%,
and the use of air conditioning reduced by half. Cities located around the
Mediterranean Sea in Europe have been using white buildings to assist cooling
for centuries. Similar simple approaches in other cities around the world would
have considerable overall benefit to the climate and the urban community.
7.10 Chapter summary
The urban environment has a major influence on local and regional climate,
which, given the growth of cities now and into the future, is creating an increas-
ing influence on the global scale. For example, cities are major contributors to
the Asian Brown Cloud, a conglomerate of pollutants that covers much of South
and Southeast Asia (GEO 2003 ). In the springtime, this material can be trans-
ported via the middle troposphere across the Pacific to the west coast of North
America.
Arnfield ( 2003 ) provides a useful summary of the relationship between UHI
in cities and climate, which is reproduced in Table 7.5 . However, unique aspects
of altitude, geographical location, and urban morphology apply to each city, and
influence the spatial and temporal variability of urban climate features, espe-
cially the UHI. Included in Table 7.5 as well are general comments about the
other impacts that cities can have on the local and regional climate, which
summarizes the discussion above.
7.11 Examples of urban websites
CEROI, Cities Environment Reports on the Internet, summarizes the state of the
environment in different cities around the world, www.ceroi.net.
CSRUR, Consortium for the Study of Rapidly Urbanizing Regions, investigates
urban climate impacts at the meso, local, and micro scales, www.urbanheat.org.
GHCC, Global Hydrology and Climate Center, US National Aeronautics and
Space Administration (NASA) provides a useful range of information on urban
climate and hydrological problems, www.ghcc.msfc.nasa.gov/ghcc_home.html.
IAUC, International Association for Urban Climate, provides information on
urban climate research and activities, including major international conferences,
www.urban-climate.org.
LTER, Long Term Ecological Research Network, a major international pro-
ject investigating ecological processes over long temporal and broad spatial
scales, including urban impacts in the environment, www.lternet.edu.