Over
the past several months, the normally restrained voice of science has
taken on a distinct note of panic when it comes to global warming.
How
did we go from debating the "uncertainty" behind climate science to
near hysterical warnings from normally sober scientists about
irrevocable and catastrophic consequences? Two reasons. First,
there hasn’t been any real uncertainty in the scientific community for
more than a decade. An unholy alliance of key fossil fuel corporations
and conservative politicians have waged a sophisticated and well-funded
misinformation campaign to create doubt and controversy in the face of
nearly universal scientific consensus. In this, they were aided and
abetted by a press which loved controversy more than truth, and by the
Bush administration, which has systematically tried to distort the
science and silence and intimidate government scientists who sought to
speak out on global warming.
But
the second reason is that the scientific community failed to adequately
anticipate and model several positive feedback loops that profoundly
amplify the rate and extent of human-induced climate change. And in the
case of global warming, positive feedback loops can have some very
negative consequences. The plain fact is, we are fast approaching – and
perhaps well past – several tipping points which would make global
warming irreversible.
In an
editorial in the Baltimore Sun on December 15th, 2004 this author
outlined one such tipping point: a self-reinforcing feedback loop in
which higher temperatures caused methane – a powerful heat-trapping
greenhouse gas (GHG) – to escape from ice-like structures called
clathrates, which raised the temperature which caused more methane to
be released and so on. Even though there was strong evidence that this
mechanism had contributed to at least two extreme warming events in the
geologic past, the scientific community hadn’t yet focused on methane
ices in 2004. Even among the few pessimists who had, we believed – or
hoped – that we had a decade or so before anything like it began
happening again. We were wrong.
In
August of 2005 a team of scientists from Oxford and Tomsk University in
Russia announced that a massive Siberian peat bog the size of Germany
and France combined was melting, releasing billions of tons of methane
as it did. The
last time it got warm enough to set off this feedback loop was 55
million years ago in a period known as the Paleocene-Eocene Thermal
Maximum or PETM, when increased volcanic activity released enough GHGs
to trigger a series of self-reinforcing methane burps. The resulting
warming caused massive die-offs and it took more than a 100,000 years
for the earth to recover. It’s
looks like we’re on the verge of triggering a far worse event. At a
recent meeting of the American Academy for the Advancement of Sciences
in St. Louis, James Zachos, foremost expert on the PETM reported that
greenhouse gasses are accumulating in the atmosphere at thirty times
the speed with which they did during the PETM. We may have just witnessed the first salvo in what could prove to be an irreversible trip to hell on earth.
There
are other positive feedback loops we’ve failed to anticipate. For
example, the heat wave in Europe that killed 35,000 people in 2003 also
damaged European woodlands, causing them to release more carbon
dioxide, the main GHG, than they sequester – exactly the opposite of
the assumptions built into our models, which treat forests as sponges
that sop up excess carbon. The
same thing is happening to a number of other ecosystems that our models
and scientists have treated as carbon sinks. The Amazon rainforest, the
boreal forests (one of the largest terrestrial carbon sinks in the
planet), and soils in temperate areas are all releasing more carbon
than they are absorbing, due to global warming-induced droughts,
diseases, pest activity, and metabolic changes. In short, many of the
things we treat as carbon sponges in our models aren’t sopping up
excess carbon; they’re being wrung out and releasing extra carbon. The
polar ice cap is also melting far faster than models predict, setting
off another feedback loop. Less ice means more open water, which
absorbs more heat which means less ice, and so on.
Even worse, we’ve substantially underestimated the rate at which continental glaciers are melting.
Climate
change models predicted that it would take more than 1,000 years for
Greenland’s ice sheet to melt. But at the AAAS meeting in St. Louis,
NASA’s Eric Rignot outlined the results of a study that shows
Greenland’s ice cover is breaking apart and flowing into the sea at
rates far in excess of anything scientists predicted, and it’s
accelerating each year. If (or when) Greenland’s ice cover melts, it
will raise sea levels by 21 feet – enough to inundate nearly every sea
port in America. In
the Antarctic seas, another potentially devastating feedback loop is
taking place. Populations of krill have plummeted by 80% in the last
few years due to loss of sea ice. Krill are the single most important
species in the marine foodchain, and they also extract massive amounts
of carbon out of the atmosphere. No one predicted their demise, but the
ramifications for both global warming and the health of marine
ecosystems are disastrous. This, too, will likely feed on itself, as
less krill means more carbon stays in the atmosphere, which means
warmer seas, which means less ice, which means less krill and so on in
a massive negative spiral. One
of our preeminent planetary scientists, James Lovelock, believes that
in the not too distant future humans will be restricted to a relatively
few breeding pairs in Antarctica. It would be comfortable to dismiss
Professor Lovelock as a doom and gloom crazy, but that would be a
mistake. A little over a year ago at the conclusion of a global
conference in Exeter England on Avoiding Dangerous Climate Change,
scientists warned that if we allowed atmospheric concentrations of GHG
to exceed 400 ppm, we could trigger serious and irreversible
consequences. We passed that milestone in 2005 with little notice and
no fanfare.
The
scientific uncertainty in global warming isn’t about whether it’s
occurring or whether it’s caused by human activity, or even if it will
"cost" us too much to deal with it now. That’s all been settled.
Scientists are now debating whether it’s too late to prevent planetary
devastation, or whether we have yet a small window to forestall the
worst effects of global warming. Our
children may forgive us the debts we’re passing on to them, they may
forgive us if terrorism persists, they may forgive us for waging war
instead of pursuing peace, they may even forgive us for squandering the
opportunity to put the nuclear genie back in the bottle. But they will
spit on our bones and curse our names if we pass on a world that is
barely habitable when it was in our power to prevent it.
And they will be right to do so.
John
Atcheson's writing has appeared in the Washington Post, the Baltimore
Sun, the San Jose Mercury News, the Memphis Commercial Appeal, as well
as in several wonk journals. Email to: atchman@comcast.net
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