Geology Reference
In-Depth Information
A relatively new and incontrovertible discovery discussed at the Exeter conference
was the acidification of the oceans that comes about when the carbon dioxide we are
pumping into the atmosphere dissolves in sea water to give carbonic acid, which in turn
releases hydrogen ions, those minuscule, highly reactive chemical beings whose increas-
ing presence in a liquid defines it as more acidic. The newly added hydrogen ions seek
out and remove carbonate ions in the sea water, a loss that eventually forces calcium car-
bonate to restore carbonate to the ocean by dissolving itself—an act of ultimate chemic-
al self-sacrifice that has dire consequences for the numerous living beings that so deftly
use chalk for making shells, coccoliths and skeletons. These include the corals, the crabs
and sea urchins, the clams and sea shells, and the tiny but climatically vital coccolitho-
phores so critical for taking carbon out of the atmosphere on a variety of timescales and
for seeding planet-cooling clouds. As the chalky structures of these diverse creatures
dissolve in a global ocean enriched with hydrogen ions put there by our lust for burning
of fossil fuels, Gaia warms even more in yet another destructive positive feedback.
Meanwhile, down in the Amazon basin, things aren't looking too promising either.
The endless sea of green forest, so vast and seemingly immune from any serious human
intervention, is also approaching a critical tipping point. Global temperature increases
may well see to it that the forest rapidly vanishes soon after 2040, when its ability to
recycle water suddenly collapses after the region has warmed above 4°C. The great ex-
panse of forest, whose canopy, seen from the cockpit of a light aircraft, looks like an
ocean of billowing green clouds stretching off towards the horizon, will be gone, re-
placed by the yellow hues of savannah vegetation with its scattered trees and drought-
tolerant grasses. The dying Amazon will release its vast store of carbon to the atmo-
sphere, as bacteria and fungi feast on the dead bodies of its giant trees and on its once
luscious vegetation, and as fires sear their way through the landscape. This carbon, in
the form of carbon dioxide and methane, will join the burgeoning legions of carbon
atoms in Gaia's atmosphere, further warming our world. The demise of the Amazon will
change global climate—the wheat belt in the mid-United States could suffer less rain-
fall, with drastic consequences for world grain supplies. Vast areas of carbon-rich trop-
ical vegetation around the world are also burning, particularly those in south-east Asia,
where farmers set fires to clear peat bogs on Borneo and Sumatra for their crops, releas-
ing large amounts of planet-warming gases to the atmosphere.
Soils hold particularly large amounts of carbon—globally about 300 times as much
as we release every year by burning fossil fuels. It is autumn in England, and the great
horse chestnut tree at Schumacher College is shedding its great, spread-eagled golden
leaves in preparation for the coming winter. On dry days, the gardeners come to take
these leaves away for compost making. Eventually, the compost is put out on the flower-
beds in the famous Dartington Hall gardens. Much of the carbon in the compost will stay
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