Environmental Engineering Reference
In-Depth Information
temperatures, some of the glaciers and ice caps will melt. The effect is expected to be
greatest in mountainous areas but even Greenland and Antarctica will be affected.
Recently some ice shelves have been breaking up on the Antarctic Peninsula, which may
be an early sign of this warming effect, though even that is debated. The net effect is to
add water to the oceans and raise their level. The combined effects of expansion and
melting are expected to lead to an increase of sea level of between 0ยท3 m and 1 m by AD
2100.
As climate changes so all the other environmental elements dependent upon climate
will experience an impact. The most obvious and immediate effects will be upon the
plant and animal kingdoms. An increased frequency of higher temperatures and lower
growing-season rainfall could cause plants to die and any animals dependent upon those
species. If the change happens slowly and with no human interference, species may
migrate to more suitable areas and other species will move in to replace them. After all, it
has happened many times in the last 2 million years. The main difference this time is that
it is happening so quickly in geological terms and there is a vast human population which
requires feeding. Species may not be able to move and so may become extinct.
Perhaps even more serious, it is likely that pests and diseases will proliferate in the
higher temperatures. Many pests are restricted in their poleward distribution by winter
cold, so warmer winters would allow an expansion of their habitat. The mosquito could
re-establish itself in southern Britain and northern Europe. Even more seriously, crop
diseases could become more prevalent to affect food supplies.
Even geomorphologically there would be consequences. The changing moisture
regime would affect river levels and channel form. Increased storminess may generate
more floods and aid run-off and erosion as a result of the more variable river regime.
Even mass movement may become more important as dry and wet spells alternate.
Decreased frost frequency would change freeze-thaw activity in tundra areas, and over
time the permafrost would melt. This would lead to greater microbial activity and, as
organic matter decomposed, large quantities of methane would be released. Methane is
another greenhouse gas which is even more efficient than carbon dioxide in absorbing
long-wave radiation.
Over longer periods of time the rates of chemical weathering would speed up as
temperatures increased, as long as moisture was available to assist the process. Soil
formation should increase, but we are still dealing with hundreds of years rather than an
instant change. This presents one problem for species migration. Although the climate of
a more poleward location might be suitable, the type of soil formation which has
developed under present climatic conditions may be unsuitable for large-scale agriculture
or forest. It is unlikely that the wheat belt of Canada could simply move northwards in
response to climate change.
Taking all environmental factors together, the impact of the predicted rapid increase in
temperature over the twenty-first century is likely to be dramatic.
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