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58September/October 2015
D
O you want to know the real
reason for the advances by
Isis in Iraq and Syria? Chang-
ing lightbulbs in America.
This is the explanation given
by John McCain, Republican chair of the
Senate armed services committee.
In May he blamed Barack Obama’s
inability to magic away Islamic State
on the president’s belief that cli-
mate change is “the biggest enemy we
have”. Never mind the role of the Iraq
war – which Mr McCain supported
– in destabilising the region, destroy-
ing the Iraqi army and creating the
opportunities Isis has exploited. Never
mind the propagation of Salafi doc-
trines by Saudi Arabia, which McCain
bravely confronts by grovelling before
its tyrants. It’s the Better Buildings
Challenge and the Solar Instructor
Training Network that allowed Isis
to capture Ramadi and Palmyra.
In fact there is a connection, but it
strengthens Obama’s contention that
“climate change constitutes a serious
threat to global security”. One of the
likely catalysts for the uprising in
Syria was a massive drought – the worst
in the region in the instrumental record
– that lasted from to . It
caused the emigration of one and a half
million rural workers into Syrian cities,
and generated furious resentment when
Bashar al-Assad’s government failed to
respond effectively. Climate models
suggest that man-made global warming
more than doubled the likelihood of a
drought of this magnitude.
But this is nothing by comparison to
the real threats to global security; in
fact, to threats that make global
ENVIRONMENT
The greatest mass
extinction on Earth –
250 million years ago –
was caused by fossil-fuel
burning.
By George Monbiot
A prehistory
of violence
September/October 2015 59
security, as understood by McCain and
Obama, look almost frivolous. As the
evidence accumulates, it now seems
that climate change was the commonest
cause of mass extinction in the Earth’s
prehistory.
In the media, if not the scientific liter-
ature, global catastrophes have long
been associated with asteroid strikes.
But as the dating of rocks has improved,
the links have vanished. Even the
famous meteorite impact at Chicxulub
in Mexico, widely blamed for the
destruction of the dinosaurs, was out of
synch by over , years.
The story that emerges repeatedly
from the fossil record is mass extinc-
tion caused by three deadly impacts,
occurring simultaneously: global
warming, the acidification of the oceans
and the loss of oxygen from seawater.
All these effects are caused by large
amounts of carbon dioxide entering the
atmosphere. When seawater absorbs
CO, its acidity increases. As tempera-
tures rise, circulation in the oceans
stalls, preventing oxygen from reaching
the depths.
The great outgassings of the past
were caused by volcanic activity that
was orders of magnitude greater than
the eruptions we sometimes witness
today. The dinosaurs appear to have
been wiped out by the formation of the
Deccan Traps in India: an outpouring of
basalt on such a scale that one river of
lava flowed for ,km. But that event
was dwarfed by a far greater one,
million years earlier, that wiped out
% of marine life as well as most of
the species on land. What was the
cause? It now appears that it might have
been the burning of fossil fuel.
Before I explain this extraordinary
contention, it’s worth taking a moment
to consider what mass extinction
means. This catastrophe, at the end of
the Permian period million years
ago, wiped out not just species within
the world’s ecosystems, but the ecosys-
tems themselves. Forests and coral
reefs vanished from the fossil record for
some million years. When, eventu-
ally, they were reconstituted, it was
with a different collection of species,
that evolved to fill the ecological
vacuum. Much of the world’s surface
was reduced to bare rubble. Were such
an extinction to take place today, it
would be likely to eliminate almost all
the living systems that sustain us. When
plants are stripped from the land, the
soil soon follows.
The latest research into the catastro-
phe at the end of the Permian is
summarised in two articles by the geol-
ogist John Mason on the Skeptical
Science site. The strongest clues all
seem to point to the same conclusion:
that the extinctions were triggered by
the eruption of an igneous belt even
bigger than the Deccan plateau: the
Siberian Traps.
As well as CO, the volcanoes there
produced sulphur dioxide, chlorides
and fluorides, causing acid rain and the
depletion of ozone. But because the resi-
dence time of carbon dioxide in the
atmosphere is greater than that of these
other gases, it’s likely to have been the
major cause of extinction. The change
of state – including a rise in oceanic
temperatures of between six and ten
degrees – was too sudden and sustained
to permit the majority of lifeforms to
adapt. The onset of mass extinction
coincides with a giant carbon spike “so
distinctive that it serves as a marker-
horizon all over the world”.
So where did the carbon dioxide come
from? Some of it would have bubbled
out of the magma. But, enormous as the
eruptions were, this alone seems insuf-
ficient to account for either the total
volume of emissions or the ratio of iso-
topes (the different atomic forms) of the
carbon entering the atmosphere. Fossil
fuel seems to fill the gap. The volcanoes
exploded through the Tunguska sedi-
mentary basin, cooking much of the
coal, petroleum and methane it con-
tained. Particles of coal fly ash have
been found in rocks as far away as the
Canadian Arctic. Rising temperatures
might also have destabilised methane
hydrates – a frozen form of natural gas
– causing the kind of runaway feedback
that terrifies some climate scientists
today. Yes: the geological record sug-
gests that fossil fuel burning might have
eliminated most life on Earth.
And today? According to a paper pub-
lished in , the current rate of
ocean acidification, caused by the burn-
ing of fossil fuels, is faster than at any
time in the past million years.
During the Permian mass extinction,
the eruption of the Siberian Traps
through the Tunguska basin seems to
have produced between one and two
gigatonnes of carbon dioxide a year.
Today fossil fuel burning produces
gigatonnes a year.
Isis? Global security? If anyone were
to survive a mass extinction on the
scale of the Permian catastrophe, they
would look back and shake their heads,
amazed that we could have considered
such issues more important. •
Were such
an extinction
to take place
today, it would
be likely to
eliminate
almost all the
living systems
that sustain us
“
This article first
appeared in the
Guardian
.
www.monbiot.com
