Volume 56, Number 18 · November 19, 2009
A Great Jump to Disaster?
By Tim Flannery
The Vanishing Face of Gaia: A Final Warning
by James Lovelock
Basic Books, 278 pp., $25.00
James Lovelock: In Search of Gaia
by John Gribbin and Mary Gribbin
Princeton University Press, 262 pp., $24.95
The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?
by Peter Ward
Princeton University Press, 180 pp., $24.95
The idea that Earth is a living thing goes back at least as far as
Plato, who according to Francis Bacon believed that the planet "was one
entire, perfect, living creature." But it was James Lovelock and his
colleague Lynn Margulis who, in the early 1970s, developed a testable
scientific hypothesis aimed at investigating Earth's lifelike
properties. Known as the Gaia hypothesis, it states that life on Earth
works to keep conditions at the planet's surface favorable to life
itself. In 2006 this led to Lovelock joining the likes of Louis Agassiz
and Charles Darwin in receiving geology's most prestigious prize--the
Geological Society's Wollaston Medal. In presenting the award the
society's president acknowledged that the Gaia hypothesis had "opened
up a whole new field of Earth Science study."
An albatross chick on Midway Atoll, raised on plastic that its parents
mistook for food from the polluted Pacific Ocean, September 2009;
photograph by Chris Jordan
The Gaia hypothesis has now evolved, according to Lovelock, into a
full-fledged scientific theory (in science hypotheses are held to be
untested ideas put forward to explain facts, while theories have been
tested and are generally considered true). Part of the testing came in
2001 when scientists from four international climate research programs
reasserted the hypothesis's basic tenets: (1) Earth "behaves as a
single, self-regulating system"; (2) "human activities are
significantly influencing Earth's environment"; (3) Earth's system is
complex and difficult to predict, and "surprises abound"; (4) the
system is characterized by "critical thresholds and abrupt changes";
and (5) Earth's system has "moved well outside the range of natural
variability exhibited over the last half million years at least." Yet
despite such support, the transformation of the hypothesis to the
status of a theory is still widely disputed.
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The Gaia concept and climate change science are intimately connected,
and Lovelock has spent most of his career trying to understand the
consequences of increased greenhouse gas concentrations in the
atmosphere. In his latest book, The Vanishing Face of Gaia: A Final
Warning, he argues that Earth's system of self-regulation is being
overwhelmed by greenhouse gas pollution and that Earth will soon jump
from its current cool, stable state into a dramatically hotter one. All
climatologists acknowledge the existence of such climatic jumps--as
occurred for example at the end of the last ice age. But chaos theory
dictates that the scale and timing of such leaps are inherently
unpredictable, which means that they cannot be incorporated into the
computer models of Earth's climate system that such scientists use to
project future climate change. Yet this is precisely what Lovelock
attempts to do--using his own computer modeling--in The Vanishing Face
of Gaia. A new climatic jump, he concludes, will occur within the next
few years or decades, and will involve an abrupt increase in average
global surface temperature of 9 degrees Celsius--from 15 to 24 degrees
Celsius (59 to 75 degrees Fahrenheit). Such a shift, he contends, will
trigger the collapse of our global civilization and the near extinction
of humanity.
In contrast, the Fourth Assessment Report of the Intergovernmental
Panel on Climate Change (IPCC), which was released in 2007, predicts a
likely rise of 2-3 degrees Celsius (4-6 degrees Fahrenheit) this
century. Lovelock argues that the IPCC projections are incorrect
because they do not include temperature jumps, yet as we've seen such
jumps are widely held to be impossible to model. He also points out
that data published subsequent to the IPCC's research cut-off point of
early 2005 show that their projections are too conservative. Support
for this view has come from a climate science summit held in Copenhagen
in March 2009 attended by 2,500 delegates, which concluded that "the
worst-case IPCC scenario trajectories (or even worse) are being
realised."
So what makes Lovelock think he can predict the timing and scale of
future climatic leaps? His findings are based on experiments conducted
with a simple kind of computer model that is used by climate scientists
to diagnose the accuracy of larger climate models. This revealed that
signs of climatic instability are likely to appear as the concentration
of CO2 reaches 400 parts per million (ppm). Then when CO2 reaches a
concentration of 400-500 ppm, the computer model predicts a sudden rise
in temperature of 9 degrees Celsius. But just before that major
temperature jump a strange thing happens--the temperature dips for a
few years. As Lovelock puts it, if his model
truly represents the Earth's response to increasing carbon dioxide,
it is scary because it implies that before the final jump to a
desert world, the climate will briefly become cooler again. This
warns that a cold summer, or even a series of them, is not proof
that global heating has ended.
Another way of putting it is that normal climatic variation will
precede Lovelock's 9 degree jump in temperature. This is hardly useful
as a predictive tool, and indeed Lovelock's approach to the problem
clearly will require further scientific corroboration before it is
accepted.
But if we assume Lovelock is right, how close might we be to the
temperature jump predicted in his model? Prior to the industrial
revolution, the concentration of CO2 in the atmosphere was 280 ppm.
Today it's around 390 ppm. But the combined warming effect of all the
greenhouse gases in the atmosphere, if expressed in terms of the
warming potential of carbon dioxide, is around 430 parts per million.
If Lovelock's model is to be believed, the fatal jump could occur any
day. Because such an imminent climate shift would have grave
consequences, it would be rash to disregard his warning out of hand.
As we try to assess Lovelock's highly individualistic work and decide
whether his message is worth listening to, there is no better guide
than John and Mary Gribbin's James Lovelock: In Search of Gaia.
Essentially a dual biography, it deftly recounts in alternating
chapters the development of climate change theory and the life of
Lovelock himself.
<end excerpt>
The rest is pretty interesting reading too:
Michael