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Climate change has unexpected effects

THT

‘Matters

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David Suzuki, }
David Suzuki
Foundation

 

On the surface, global’warming may seem like a pretty
simple process. Excess “greenhouse” gases trap heat in
the atmosphere, making the world warmer. But that’s not
all that happens. Our climate is actually very complex and
intimately connected to life on Earth. Seemingly minor
changes can have profound repercussions.

_ Consider ocean currents. Remember that big block-
buster movie a few years ago based on the theory of
rapid climate change? Well, it wasn’t exactly rocket sci-
ence, but it was based on a kernel of truth. In the movie,
global warming triggers a collapse of the “thermohaline
circulation,” a system of currents including the Gulf
Stream that circulate water in the Atlantic. Eastern North
America and Western Europe depend on this circulation
to bring warmer water up from the tropics and help mod-

erate their climates.

According to the Hollywood version, a collapse of
the thermohaline circulation would thrust New York and
London into an instant ice age. Reality is less dramatic, of
course, but recent evidence has found that this massive
system can indeed be disrupted and it has happened fairly
recently. A study by NASA’s Goddard Institute for Space
Studies looked at the last event, which is thought to have
occurred 8,200 years ago when an ice dam in Canada
burst, sending a massive flood of freshwater into the
Arctic Ocean. This reduced the Arctic’s salinity and
slowed the thermohaline current, dropping temperatures
in Greenland by up to seven degrees Celsius for three
centuries.

Results of another study, published this fall in Nature,
show that the thermohaline current may again be weaken-
ing, this time as a result of melting snow and glaciers due

to climate change. Last year, a team of scientists from the

UR’s National Oceanography Centre sampled water tem-
perature and salinity every 50 kilometres in the Atlantic
between the Bahamas and the Canary Islands. They com-
pared data from these samples to data from water collect-
ed on four other trips dating back as far as 1957 and con-
cluded that today’s current seems to be 30 percent weaker
than it was 50 years ago. So far, air temperatures in
Western Europe do not appear to have been affected by
the change.

In the tropics, however, small changes in air tempera-
ture attributed to global warming are believed to be
responsible for the widespread extinction of amphibians.
According to a recent paper published in Nasure, climate
change is altering cloud cover in the mountains of
Central and South America, leading to cooler days and
warmer nights. This change creates ideal living conditions
for a pathogenic fungus, which attaches itself to amphib-

ians, such as frogs, causing dehydration and eventually
death.

The fungus has taken a real toll in the tropical
Americas, where 67 percent of 110 species of harlequin
frog in the region have died out in just 20 years. Hardest
hit have been those species living at mid-elevations, where
researchers surmise conditions are optimal for growth of
the fungus. They conclude that, “climate-driven epidemics
are an immediate threat to biodiversity.”

Indeed, a changing climate has also been implicated

 

in the increase of nematode parasites in musk oxen and
the continuing destruction of pine forests by the moun-
tain pine beetle. The relationship between an increase in
pathogens and a changing climate is also cause for con-
cern in regards to human health. A warmer world may be
a sicker one for humans as well.

Climate change is not a simple process. Our atmos-
phere, our oceans, and all life on the planet are intercon-
nected. Seemingly small alterations in one area can rever-
berate through the entire system, affecting the health of a
tremendous variety of species—including us.