Geology Reference
In-Depth Information
Dartmoor speaks a warning, for what happened here so long ago is now happening all
over the planet. There is now no part of Gaia left untouched by the human hand, not even
the furthest reaches of Antarctica or the deepest depths of the ocean, for the contamin-
ated atmosphere connects everything and reaches almost everywhere on the Earth's sur-
face. Everywhere 'development' chews up wild places, spitting them out as the 'stuff'
we increasingly see as indispensable for our lives. How will Gaia respond to this on-
slaught? According to James Lovelock's latest understanding (outlined in his 2006 book
The Revenge of Gaia
), the answer will almost certainly be abrupt, catastrophic climate
change, which will increase global temperatures to levels not experienced on the planet
for at least 55 million years. The destruction of New Orleans by hurricane Katrina in
September 2005, as well as many other recent serious climatic events, are a sign that we
have unleashed Gaia's wrath, and that in her desperation she seems poised to respond
to our onslaught with an even greater one of her own which will kill vast numbers of
people and lay low our so-called civilisation.
Gaia in her Natural State
So what was Gaia's state of being before we began to disturb her—what was she up
to? How can we even attempt to answer such questions? Some of the answers are to be
found in Gaia's diverse modes of speech: as bubbles of ancient air locked up in polar
ice, as different versions of her chemical beings laid down in rocks, and as the signs
left by ice, wind and water on the very rocks themselves. These are Gaia's memories,
some faint, some vivid, but for the most part amazingly coherent over space and time.
These memory traces tell us that for most of her life Gaia has gone through million-year
periods of relative warmth, and equally long periods of cooler temperatures. But things
have changed in the more recent past. We know for certain that for the last two million
years Gaia has been moving in and out of ice ages with extraordinary regularity. Every
100,000 years over the last 700,000 years ice has spread down from the Arctic regions
into the northern temperate latitudes, covering them with glaciers kilometres thick, and
the world has cooled. We have already seen in
Figure 5
how the oscillations are stun-
ningly regular, as regular as the heartbeats of Gaia's own living animals, but with a very
slow pulse, the sort of pulse that could only belong to a great whale of a planet coursing
silently through space, a pulsing back and forth from ice to warmth in a cycle about fifty
times as long as the entire span of Western civilization. Periods of ice have dominated
most of the time, but every 100,000 years, for a relatively brief spell, Gaia has experien-
ced a time of warmth before plunging back down into an icy state (
Figure 5
). Carbon di-
oxide and methane, two of Gaia's key greenhouse gases, have pulsed in step with these
