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06/15/2006
Global Warming
The topic of global warming is certainly a true ‘hot spot’ these
days. And with former Vice President Al Gore receiving quite a
bit of publicity with his own work in this area, including the
movie “An Inconvenient Truth,” I thought it would be timely to
pass on some interesting comments from an article titled
“Fueling Our Future” by Jonathan Shaw in the May-June issue of
Harvard Magazine. [Forwarded to me by my friend Trader
George.]
Personally, I used to be a skeptic on global warming but I was
converted a number of years ago. Regarding the following,
however, I have no idea and won’t comment myself. I’ll let the
true experts debate the topic instead. In the meantime, this is
merely thrown out there as food for thought.
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Daniel Schrag is a professor of earth and planetary sciences at
Harvard who hosts a weekly “energy breakfast” where some of
his colleagues, many dating back to the first oil crisis of the early
1970s, discuss the topics of the day.
The following excerpt of Jonathan Shaw’s is taken from one
particular discussion on nuclear power which veered off into
“CO2 and the Sea.”
“The imperative to embrace nuclear power – despite all its
problems and limited usefulness – hints at the severity and
irreversibility of some climate impacts. Though whole regional
ecosystems are forecast to fail, unable to provide basic
necessities such as water and food crops, Schrag has found that
one dimension of climate change, in particular, gets people’s
attention: rising seas.
“On the geologic time scale, sea levels rise and fall in inverse
relation to land-based glaciation. The end of the last ice age, for
example, 14,000 to 12,000 years ago, was punctuated by a
meters-per-decade rise in sea level (totaling nearly 53 feet). Ever
since then, the earth’s climate has been good to us. An
unprecedented period of climate stability began 11,600 years
ago, about the time when archaeologists date the dawn of human
civilization. Had the climate continued to cycle between periods
of warm and cold as it had during the previous 400,000 years,
when atmospheric concentrations of carbon dioxide fluctuated
between 180 and 280 parts per million (ppm) – closely tracking
the changes in temperature – we would be in the midst of a
20,000-year-long cooling trend.
“Instead, atmospheric concentrations of CO2 remained near 280
ppm (the established upper range) through the early 17th century,
and then began to rise steadily with the advent of the Industrial
Revolution. When one American scientist began measuring the
gas in 1958, the concentration was still just 315 ppm, only about
12 percent higher than the historic norm. But by 2005, it had
reached 380 ppm, a level not seen in at least 650,000 years (the
farthest back that ice cores with embedded bubbles can currently
be extracted). Last year was reportedly the warmest in at least
several thousand years (statistically tied with 1998), and the
previous 10 included the nine warmest years since record-taking
began in the late nineteenth century.
“ ‘The effect of CO2 on temperature is not theoretical,’ says
Schrag. ‘Just look at Venus.’ Venus is closer to the sun, but its
surface is so reflective that if it shared our atmosphere, it would
be much colder than Earth. In fact, temperatures on the
Venusian surface reach 900 degrees Fahrenheit. The planet’s
CO2-rich atmosphere traps heat, causing a runaway greenhouse
effect.
“Schrag has done a lot of thinking about the effects of CO2 on
planets, including Earth. More than a decade ago, working with
Hooper professor of geology Paul Hoffman, he developed
evidence to support a theory that the earth has been completely
encased in ice several times in its history. Though the geological
evidence for glaciers at the equator is widespread and
convincing, an explanation for how Earth could have emerged
from total glaciation was missing at first. After all, a frozen
planet is a white globe that would reflect most of the sun’s heat-
energy back into space, locking its own surface perpetually in
ice. The frigid embrace might have lasted forever – except for
CO2 Volcanic eruptions release the gas in abundance. Today,
photosynthesis and rain and ocean waters absorb much of that
CO2 and some of it even becomes trapped in sediments at the
bottom of the sea. But when the oceans were frozen and plant
life was suspended, CO2 could not be absorbed. Slowly, over
millions of years, CO2 from volcanic eruptions built up in the
atmosphere, raising temperatures until the ice began to melt.
“That same process, now caused primarily by emissions from
fossil fuels, has set in motion an increase in temperature with
effects that won’t be fully felt for thousands of years. That is
because the ocean acts as an enormous brake on climate change,
absorbing half the man-made CO2 and much of the heat. The
top 10 to 15 feet of water alone, a small fraction of the total
volume, store as much energy as the entire atmosphere.
[Hurricanes, whose increased frequency and intensity have been
linked to higher sea-surface temperatures, feed off this energy.]
Even if we could stabilize atmospheric concentrations of
greenhouse gases at current levels, the earth would continue to
warm.
“The losses caused by Katrina, the costliest hurricane in U.S.
history, pale by comparison to what might come. If just one-
fourth of the land-based ice in Greenland and the western part of
Antarctica were to melt, sea level would rise three and a half
meters and all of South Florida, as far north as Lake Okeechobee,
would be under water. *[ed. note: I was watching Al Gore on
“This Week” recently and George Stephanopoulus was ridiculing
Gore for his projections on water levels, but I now realize Gore
was basically quoting the Harvard group.] ‘South Florida alone
must be worth a few trillion dollars at least,’ notes Schrag, whose
opinion about spending billions to rebuild New Orleans in the
same spot using dikes and levees (‘a very dangerous strategy’)
appeared recently in the New York Times. ‘I can’t tell you if it
is going to happen in 500 years or 100 years. But a hundred
years is possible,’ he says. ‘Our understanding of glaciers is so
bad, we don’t know how fast they are going to melt.’ We do
know that before 2050, atmospheric CO2 will cross the 500 ppm
threshold, a level last seen during the Eocene, 55 million to 36
million years ago. There were palm trees in Wyoming and
crocodiles in the Arctic then. Antarctica was a coniferous forest.
Because there were no continental ice sheets, sea level was 100
meters (328 feet) higher than it is today.
“Already, glaciers in Greenland and West Antarctica have begun
to melt. Two separate studies published in Science early in 2006
showed that these ancient ice sheets were shrinking faster than
expected, implying that estimates of global sea-level rise in this
century are too low. Scientists know that when the ice in
Greenland and West Antarctica melts or collapses completely,
the rise in sea level will drown coastal civilizations all around the
world. Each one has the potential to raise global sea level by
about six or seven meters, or if combined, approximately 42 feet.
That is nothing compared to what would happen if vast East
Antarctica, which is poorly understood, also lost mass. The
submarine portion of that ice sheet, which is vulnerable to
melting from below due to warm ocean water, is itself as large as
the West Antarctic. The entire East Antarctic ice sheet
represents more than 200 feet of potential sea level change. Just
slowing the rate at which continental ice sheets melt is clearly in
humanity’s best interests.
“The latest revelations from Greenland and the West Antarctic
surprised scientists because atmospheric CO2 today is only about
a third higher than its historic upper range of 280 ppm during the
last 400,000 years. By 2050, CO2 concentrations – which are
increasing 200 times faster than they ever have naturally – will
be double the historic level. If a small increase in CO2 can
trigger the new ice-mass losses that scientists have recently
observed, finding a solution to the carbon problem is urgent.”
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Now discuss amongst yourselves.
Hott Spotts will return next week.
Brian Trumbore
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