Geoscience Reference
In-Depth Information
own eyes, and measured it with his own instruments. In science, as in life, when theory conflicts with
evidence, it's usually the theory that's wrong. But try as he might, Joe couldn't think why. The ice
began to haunt his dreams. He found himself tossing and turning at night, waking up in a sweat, think-
ing, “Did the Earth really
do
this?”
And then suddenly he had it. He conjured up a way out of the ice catastrophe. The melters of the
Snowball, the evaders of the ice catastrophe, were volcanoes. Then as now, Earth was scattered with
volcanoes, which periodically spilled out molten rock and heat. The Snowball wouldn't have stopped
them. They could erupt perfectly happily, even under ice—as they do today in Iceland.
The lava from these volcanoes wouldn't itself have been enough to melt the Snowball. But when
volcanoes disgorge their lava, gas comes too. Curling plumes of gas rise from the sides of an active
volcano. An eruption can fling great clouds of gas high into the atmosphere. Gas bubbles up from hot
vents beneath the sea. And one of the main gases to come from the heart of a volcano is also a villain
in the world today: carbon dioxide.
Carbon dioxide, CO
2
, is the gas that threatens us all with global warming. Every molecule of car-
bon dioxide traps a little heat. The more CO
2
you have in the sky, the more heat you trap. The effect
is, famously, like that of a greenhouse. Carbon dioxide lets sunlight in, but prevents the Earth's body
heat from escaping, providing a very effective and cosy way of warming a planet up.
And here's what Joe suddenly, thrillingly realized. Each volcanic eruption would pour a little more
CO
2
into the sky, and gradually the greenhouse would heat up. Carbon dioxide would build up in the
air, and wrap the Earth in a blanket of warmth. This blanket would trap more and more heat, and after
millions of years the heat would finally melt the Snowball.
The idea is even cleverer than it sounds. In normal times, carbon dioxide doesn't usually build
up in the air like that. Volcanoes are erupting all the time, but the Earth usually has a sort of built-in
thermostat operated by rainwater, which strips out the excess CO
2
. When rain falls through the air it
picks up CO
2
and, as a result, becomes slightly acidic. The acidified rain lands on rocks and reacts
with them chemically, handing over its load of dissolved CO
2
. By this mechanism, any excess CO
2
is
scrubbed out of the air and locked away inside a new rocky matrix. Over millions of years the Earth
ends up more or less in balance, never too hot or too cold.
But if the planet freezes over and its rocks are blanketed with ice, the CO
2
thermostat switches off.
Now there is all give and no take. Volcanoes keep giving out carbon dioxide, but the ice-covered rocks
can no longer soak it back up again. Left unchecked in this way, the greenhouse effect of the CO
2
will
build and build until it's ten times, even a hundred times, what we have today. With our puny little
efforts to pollute our atmosphere by burning oil and coal, we'll maybe double the amount of carbon
dioxide. Over millions of years the runaway volcanoes would have sent CO
2
levels spiralling beyond
the wildest imaginings of any oil conglomerate. The Earth's atmosphere would have turned into a fur-
nace.
The aftermath of the melting would have been hell on Earth. Dante, says Joe, would be proud
of it. For tens of thousands of years—until the excess carbon dioxide was finally locked back up in
the rocks, and the furnace switched off—any slime creatures that had survived the freeze would have
found themselves scorched. These would be prime conditions, perhaps, to weed out all but the few,
and to set the stage for the emergence of a whole new kind of life.
Joe's idea was ingenious. So what did he do with it? Embark on a round of conferences and
lectures presenting it to his peers? Publish the idea in an acclaimed scientific journal? Not exactly.
Though the academic world runs on conference presentations and published papers, Joe did little of
either. The graduate student who made the measurements on the Pichi Richi fold presented the res-
