Higher temperatures the world over do not just result in rising sea levels. According to a recent report produced by scientists from 50 countries, global warming has endangered even human health
THE well-being of any species is dependent on the natural environment it
exists in. A recent report on the effect of
climate change on human health
released by the Intergovernmental Panel
on Climate Change (IPCC), suggests that
the rise in global temperatures could
directly or indirectly affect human
health (Science Update, September-
October, 1995).
Deaths and injuries caused due to
heat waves, hurricanes and other
extreme climatic conditions are some
direct consequences. Skin cancers and
eye disorders such as cataracts are
caused due to exposure to the sun's
ultra-violet rays.
The indirect effects are more complicated as they involve the study of
complex ecological relationships and
habitats. Factors such as drought, rising
sea levels and new storm patterns could
pave the way for water-borne infections
and reduce drinking water sources.
Reduced agricultural production could
bring about famine like conditions.
The lower nutritional status would
bring down body-resistance to
various infections.
Atmospheric change may further
the spread of diseases by encouraging
the breeding of microbes like the Aedes
aegyph mosquitoes - prime carriers of
dengue and yellow fever. According to
Paul Epstein, professor of tropical
medicine at the Harvard School of
Public Health, these mosquitoes have
increased their range of habitat. Earlier
they were limited to altitudes of less
than 1,000 in in Costa Rica, Colombia
India and Kenya, but today they are
found even above 2,000 in. Michael
Loevinsohn, an ecologist at the New
Delhi-based International Development
Research Centre believes that a rise in
temperature by 1oC in 1987 corresponded with an increase in the number of
malaria cases by 337 per cent.
The El Nino effect is also stated to be
a cause of greater ill-health. Such a condition occurs when warm spells followed by heavy rains lead to a cyclical
warming of the tropical Pacific Ocean.
This in turn causes a spate of infectious
diseases. Climatic disruptions in the
form of floods and droughts brought
about by El Nino have been indirectly responsible for the rise in
rodent populations, which are
known to carry numerous infectious pathogens. The 1993 outbreak of the Hantavirus respiratory
illness in the US, is a fallout of such
climatic shifts. Initially, excess
rainfall led to an abundance of
food for the mice but the drought
which followed took its toll on
their predators, the end result
being a 10-fold increase in the deer
mice population within a year. By
June 1995, 106 cases of the disease
were reported from 23 states, half
of them fatal.
The warming of the world's
oceans may be precipitating the
El Nino condition even more.
Since the '80s such conditions
have shown up with ever greater frequency and
persistance. Temperatures in the Indian, Pacific and
Atlantic oceans are reported to have
gone up in the last one year. And during
the last decade, even the polar ice caps
registered a rise of 1oC.
Climatologists from the University
of Delaware, USA, hypothesise using
climate models, that a rise in temperature by 2-4oC will lead to a two-fold
increase in the number of hot days during summer. Thus they suggest that the
number of heat related deaths in New
York would go up from 320 to 880,
while in Cairo the numbers would catapult from 281 to 1,125 each summer.
Epstein suggests that an increase in
the global surveillance of infectious diseases is required in order to establish the
link between the two. "We also need to
integrate health surveillance with environmental monitoring so we can anticipate and sometimes even predict where it is going to be hot and rainy, so we
know where malaria is going to surge,"
he says.
The IPCC report concludes by saying
that "We must see disease as the outcome of multiple conditions arising
from changes not only within cells, but
around the globe, including changes in
climate and economic patterns."
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