Colleagues and friends,
Please read this very, very important and informed article from Mike Davis
coming via my US colleague Adam Jones
This one, indeed, at the very nub of one Crisis Forum is about and for...
(see also Mike Davis, Late Victorian Holocausts, the most extraordinary book
linking economic-political 'system' and climate)
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Subject: 'Melting Away' from The Nation
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Melting Away
by Mike Davis
The genesis of two category-five hurricanes (Katrina and Rita) in a row
over the Gulf of Mexico is an unprecedented and troubling occurrence.
But for most tropical meteorologists the truly astonishing "storm of
the decade" took place in March 2004. Hurricane Catarina--so named
because it made landfall in the southern Brazilian state of Santa
Catarina--was the first recorded South Atlantic hurricane in history.
Textbook orthodoxy had long excluded the possibility of such an event;
sea temperatures, experts claimed, were too low and wind shear too
powerful to allow tropical depressions to evolve into cyclones south of
the Atlantic equator. Indeed, forecasters rubbed their eyes in
disbelief as weather satellites downlinked the first images of a
classical whirling disc with a well-formed eye in these forbidden
latitudes.
In a series of recent meetings and publications, researchers have
debated the origin and significance of Catarina. A crucial question is
this: Was Catarina simply a rare event at the outlying edge of the
normal bell curve of South Atlantic weather, just as, for example, Joe
DiMaggio's incredible fifty-six-game hitting streak in 1941 represented
an extreme probability in baseball (an analogy made famous by Stephen
Jay Gould)? Or was Catarina a "threshold" event, signaling some
fundamental and abrupt change of state in the planet's climate system?
Scientific discussions of environmental change and global warming have
long been haunted by the specter of nonlinearity. Climate models, like
econometric models, are easiest to build and understand when they are
simple linear extrapolations of well-quantified past behavior--that is,
when causes maintain a consistent proportionality to their effects.
But all the major components of global climate--air, water, ice and
vegetation--are actually nonlinear: At certain thresholds they can
switch from one state of organization to another, with catastrophic
consequences for species too finely tuned to the old norms. Until the
early 1990s, however, it was generally believed that these major
climate transitions took centuries, if not millennia, to accomplish.
Now, thanks to the decoding of subtle signatures in ice cores and
sea-bottom sediments, we know that global temperatures and ocean
circulation can, under the right circumstances, change abruptly--in a
decade or even less.
The paradigmatic example is the so-called "Younger Dryas" event, 12,800
years ago, when an ice dam collapsed, releasing an immense volume of
meltwater from the shrinking Laurentian ice sheet into the Atlantic
Ocean via the instantly created St. Lawrence River. This "freshening"
of the North Atlantic suppressed the northward conveyance of warm water
by the Gulf Stream and plunged Europe back into a thousand-year ice
age. Abrupt switching mechanisms in the climate system--such as
relatively small changes in ocean salinity--are augmented by causal
loops that act as amplifiers. Perhaps the most famous example is
sea-ice albedo: The vast expanses of white, frozen Arctic Ocean ice
reflect heat back into space, thus providing positive feedback for
cooling trends. Alternatively, shrinking sea-ice levels increase heat
absorption, accelerating both further melting and planetary warming.
Thresholds, switches, amplifiers, chaos--contemporary geophysics
assumes that earth history is inherently revolutionary. This is why
many prominent researchers--especially those who study topics like
ice-sheet stability and North Atlantic circulation--have always had
qualms about the consensus projections of the Intergovernmental Panel
on Climate Change (IPCC), the world authority on global warming.
In contrast to Bushite flat-earthers and shills for the oil industry,
these researchers base their skepticism on fears that the IPCC models
fail to adequately allow for catastrophic nonlinearities like the
Younger Dryas. Where other researchers model the
late-twenty-first-century climate that our children will live with upon
the precedents of the Altithermal (the hottest phase of the current
Holocene period, 8,000 years ago) or the Eemian (the previous, even
warmer interglacial episode, 120,000 years ago), growing numbers of
geophysicists toy with the possibilities of runaway warming returning
the earth to the torrid chaos of the Paleocene-Eocene Thermal Maximum
(PETM: 55 million years ago), when the extreme and rapid heating of the
oceans led to massive extinctions.
Dramatic new evidence has emerged recently that we may be headed, if
not back to the dread, almost inconceivable PETM, then to a much harder
landing than envisioned by the IPCC. As I flew toward Louisiana and the
carnage of Katrina three weeks ago, I found myself reading the August
23 issue of EOS, the newsletter of the American Geophysical Union. I was
pole-axed by an article titled "Arctic System on Trajectory to New,
Seasonally Ice-Free State,"
co-authored by twenty-one scientists from almost as many universities
and research institutes. Even two days later, walking among the ruins
of the Lower Ninth Ward, I found myself worrying more about the EOS
article than the disaster surrounding me.
The article begins with a recounting of trends familiar to any reader
of the Tuesday Science section of the New York Times: For almost
thirty years, Arctic sea ice has been thinning and shrinking so
dramatically that "a summer ice-free Arctic Ocean within a century is a
real possibility." The scientists, however, add a new observation--that
this process is probably irreversible. "Surprisingly, it is difficult
to identify a single feedback mechanism within the Arctic that has the
potency or speed to alter the system's present course."
An ice-free Arctic Ocean has not existed for at least 1 million years;
the authors warn that the earth is inexorably headed toward a
"super-interglacial" state "outside the envelope of
glacial-interglacial fluctuations that prevailed during recent Earth
history." They emphasize that within a century, global warming will
probably exceed the maximum Eemian temperature and thus obviate all the
models that have made this their essential scenario. They also suggest
that the total or partial collapse of the Greenland Ice Sheet is a real
possibility--an event that would definitely throw a Younger Dryas
wrench into the Gulf Stream.
If they are right, then we are living on the climate equivalent of a
runaway train that is picking up speed as it passes the stations marked
"Altithermal" and "Eemian." "Outside the envelope," moreover, means
that we are not only leaving behind the serendipitous climatic
parameters of the Holocene--the last 10,000 years of mild, warm weather
that have favored the explosive growth of agriculture and urban
civilization--but also those of the late Pleistocene that fostered the
evolution of Homo sapiens in eastern Africa.
Other researchers undoubtedly will contest the extraordinary
conclusions of the EOS article and--we must hope--suggest the
existence of countervailing forces to this scenario of an Arctic albedo
catastrophe. But for the time being, at least, research on global
change is pointing toward worst-case scenarios.
All of this, of course, is a perverse tribute to industrial capitalism
and extractive imperialism as geological forces so formidable that they
have succeeded in scarcely more than two centuries--indeed, mainly in
the last fifty years--in knocking the earth off its climatic pedestal
and propelling it toward the nonlinear unknown.
The demon in me wants to say: Party and make merry. No need now to
worry about Kyoto, recycling your aluminum cans or using too much
toilet paper, when, soon enough, we'll be debating how many
hunter-gatherers can survive in the scorching deserts of New England or
the tropical forests of the Yukon.
The good parent in me, however, screams: How is it possible that we can
now contemplate with scientific seriousness whether our children's
children will themselves have children? Let ExxonMobil answer that in
one of its sanctimonious ads.
This article can be found on the web at:
http://www.thenation.com/doc/20051024/davis
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