EarthTalk: How is it that global warming could
cause an increase in health problems and disease epidemics?
Do we have any evidence that it is already happening?
– Jim Merrill, Provo, UT
Union of Concerned Scientists reports that, thanks
to global warming, insects previously stopped by
cold winters are already moving to higher latitudes,
a phenomenon that could expose an extra two billion
people, mostly in developing countries, to the dengue
virus over the next half century.
credit: U.S. Department of Agriculture
warming isn’t just bad for the environment. There
are several ways that it is expected to take a toll on human
health. For starters, the extreme summer heat that is becoming
more normal in a warming world can directly impact the health
of billions of people.
high air temperatures contribute directly to deaths from
cardiovascular and respiratory disease, particularly among
elderly people,” reports the World Health Organization
(WHO). “In the heat wave of summer 2003 in Europe,
for example, more than 70,000 excess deaths were recorded.”
adds that high temperatures also play a role in elevated
levels of ozone and other air pollutants known to exacerbate
respiratory and cardiovascular problems. And according to
the non-profit Union of Concerned Scientists (UCS), warmer
temperatures and higher levels of atmospheric carbon dioxide
can stimulate plants to grow faster, mature earlier and
produce more potent allergens. “Common allergens such
as ragweed seem to respond particularly well to higher concentrations
of carbon dioxide, as do pesky plants such as poison ivy.
Allergy-related diseases rank among the most common and
chronic illnesses…” reports the group.
way global warming is bad for our health is that it increases
extreme weather events that can injure or kills large numbers
of people. According to WHO, the number of weather-related
natural disasters has more than tripled since the 1960s.
Likewise, increasingly variable rainfall patterns combined
with higher overall temperatures are leading to extended
droughts around the world. “By the 2090s, climate
change is likely to widen the area affected by drought,
double the frequency of extreme droughts and increase their
average duration six-fold,” reports WHO. One result
is likely to be a downturn in agricultural productivity
along with a spike in malnutrition. Another is less access
to safe drinking water, a trigger for poor sanitation and
the spread of diarrheal diseases—not to mention resource
most worrying to public health experts, though, is the potential
for global warming to cause a spike in so-called “vector-borne
diseases” like schistosomiasis, West Nile virus, malaria
and dengue fever. “Insects previously stopped by cold
winters are already moving to higher latitudes (toward the
poles),” reports UCS. Researchers predict that thanks
to global warming an extra two billion people, mostly in
developing countries, will be exposed to the dengue virus
over the next half century.
related fear is that thawing permafrost in Polar Regions
could allow otherwise dormant age-old viruses to re-emerge.
Earlier this year, French and Russian researchers discovered
a 30,000 year old giant virus, previously unknown to science,
in frozen soil in Russia’s most northerly region.
While the virus, which researchers dubbed Pithovirus sibericum,
is harmless to humans and animals, its discovery has served
as a wake-up call to epidemiologists about the potential
re-emergence of other viruses that could make many people
sick. While some of these re-emergent viruses might also
be new to science, others could be revitalized versions
of ones we thought we had eradicated, such as smallpox.
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