Geography Reference
In-Depth Information
effect. Cities are warmer than the surrounding
countryside at night and often, especially in high
latitudes, during the daytime. In Tokyo,
anthropogenic heat raises the urban surface
temperature by around 1.5°C in summer and
2.5°C degree in winter, and urban land-use effects
raise temperatures by about 1°C in both seasons
(Ichinose 1997). In large mid-latitude cities during
summer heatwaves, the release of warm air from
cooling machinery makes city streets extremely
hot and excess deaths occur, as in Greece and the
eastern United States in the summer of 1998.
While most cities experience fogs and storm
rains, the rarer tornadoes, cyclones, heat waves,
droughts, bush fires and haze problems are more
difficult to plan for. Part of the growing risk arises
from the rapid growth of cities in areas affected by
severe tropical revolving storms, known locally as
cyclones, hurricanes or typhoons. Before 1987, no
single event produced urban storm damage claims
of over a billion dollars. Since then, claims have
included those from Cyclone Iniki in 1992 ($1.4
billion), Hurricane Hugo in 1989 ($5.8 billion)
and Hurricane Andrew in 1992 ($20 billion). Such
huge losses and possible changes in world weather
patterns may lead to rises in premiums and even
insurance company collapses. The building design
and urban land use zoning needed to reduce
cyclone damage benefits from the use of
Geographical Information Systems (GIS).
However, geographers also contribute to the
behavioural studies that examine how people's
preparedness for, and response to cyclones may be
improved.
URBAN VULNERABILITY TO AIR
POLLUTION
Three general types of air pollution have affected
cities in the twentieth century:
•
sulphur dioxide (SO2) and soot from coal
burning;
•
lead emissions from motor vehicles;
•
oxides of nitrogen and fine particulate matter
from motor vehicles.
In Britain, as trends in Greater Manchester
demonstrate (Figure 9.1), the worst effects of the
first two have largely been overcome by technical
advances and legislation, but the effects of traffic-
related pollution remain a major concern.
Elsewhere in the world, all three forms of air
pollution can be found.
Lead from motor vehicles has caused much
concern for the health of children, especially in
school playgrounds close to main roads. Lead
concentrations are high close to the kerb but 10
to 20 m away from the road are much lower.
Concentrations are also high in the soil close to
traffic lights, where vehicles are temporarily
stationary. Atmospheric lead began to decline in
Europe with the introduction of lead-free petrol,
development of more efficient vehicle engines and
Figure 9.1
The decline in
smoke, sulphur dioxide and
lead (A) in the air in Greater
Manchester and the fall in the
death rate due to bronchitis.
Smoke and sulphur dioxide
data (B) are for central
Manchester, bronchitis death
rate for the city of Manchester
as a whole and lead data for
the places indicated in
different parts of Greater
Manchester.
Source:
Environment and
Development Department,
Manchester City Council.
