- Is global warming real? You can find
experts who say that it's a clear and present danger. You can also find
others who insist that the whole issue isn't worth worrying about.
- Which of these groups should we believe?
- Jonathan Overpeck, a scientist with the
National Oceanic and Atmospheric Administration (NOAA) has some thoughts
- First of all, he doesn't have a high
level of trust for the opinions of politically motivated people "who
are not climate change scientists themselves and therefore lack firsthand
- Conversely, he would be inclined to trust
what real climate scientists say. These men and women, he points out, have
actually done the research. And more often than not, he adds, they've had
their work published, which means it has been reviewed by other knowledgeable
scientists. And, according to Overpeck, among these specialists, "There
is a strong consensus that global warming is taking place." So the
guys who know best say, yes, global warming is taking place.
- Recently, Overpeck and an international
team of 20 researchers worked together to summarize what we know about
the climate changes that have taken place in the past 400 years. Their
tools included analyzing and reviewing the growth of tree rings, examining
lake sediments, studying written records and checking gas bubbles trapped
- Altogether, Overpeck and his colleagues
used 30 different records to check and cross-check their results. What
they discovered is that a Little Ice Age began around 1600 and continued
until it reached its coldest around 1850.
- Since then, the climate has warmed dramatically.
Our climate is today warmer than it's been in 400 years.
- So, according to the scientific evidence,
global warming truly is taking place. But what are the likely consequences
- You've probably heard about the potential
for coastal flooding, but there are other results to consider.
- Rising temperatures, for example, are
causing the Alaskan permafrost to thaw. "The permafrost is close to
the melting point anyway," says Gunter Weller from the University
of Alaska, "and it doesn't require much of a temperature increase
to cause it to thaw."
- In the last century, the permafrost in
Alaska has warmed between two and four degrees. Since about 80 percent
of Alaska rests on permafrost, the consequences are enormous. When ice
masses in the permafrost thaws, the land underneath it becomes unstable.
Soon there are pits and depressions, many of which are filled with water.
This causes houses, roads and airport runways to become either unusable
or in need of expensive repair. And as the thawing continues, the unstable
ground could also pose problems for the Alaska Pipeline.
- The problems don't end there. "A
lot of the forests here are underlain by permafrost," explains Weller's
colleague, Tom Osterkamp. "As the temperatures rise, the foundation
for the whole eco system melts out from underneath it. The forest areas
turn into marshes, fens or ponds."
- If the forests aren't killed by standing
water, they face a new threat. Insects that don't survive in colder temperatures
are now gaining a foothold in Alaska. "There are unprecedented outbreaks,"
Weller points out. "The losses are higher than we've ever observed
- Permafrost thawing may also contribute
further to global warming. As the climate warms, dead vegetation that used
to be locked in the permafrost, can now release its carbon and add to the
green house gases implicated in global warming. This can effect everyone.
- For climate scientists, the debate about
global warming doesn't seem to be about "Is this happening?"
Rather, it's "What is happening and what are we going to do about