A New Ice Age: The Day After
Tomorrow A William Curry is a serious,
sober climate scientist, not an art critic. But he has spent a lot of time
perusing Emanuel Gottlieb Leutze’s famous painting George Washington Crossing
the Delaware, which depicts a boatload of colonial American soldiers making
their way to attack English and Hessian troops the day after Christmas in 1776.
’Most people think these other guys in the boat are rowing, but they are
actually pushing the ice away,’ says Curry tapping his finger on a reproduction
of the painting. Sure enough, the lead oarsman is bashing the frozen river with
his boot. ’I grew up in Philadelphia. The place in this painting is 30 minutes
away by car. I can tell you, this kind of thing just doesn’t happen
anymore.’ B But it may again soon. And ice-choked scenes,
similar to those immortalised by the sixteenth century Flemish painter Pieter
Brueghel the Elder, may also return to Europe. His works, including the 1565
masterpiece Hunters in the Snow make the now-temperate European landscapes look
more like Lapland. Such frigid settings were commonplace during a period dating
roughly from 1300 to 1850 because much of North America and Europe was in the
throes of a little ice age. And now there is mounting evidence that the chill
could return. A growing number of scientists believe conditions are ripe for
another prolonged cool down, or small ice age. While no one is predicting a
brutal ice sheet like the one that covered the Northern Hemisphere with glaciers
about 12,000 years ago the next cooling trend could drop average temperatures 5
degrees Fahrenheit over much of the United States and 10 degrees in the
Northeast, northern Europe, and northern Asia. C ’It
could happen in 10 years,’ says Terrence Joyce, who chairs the Woods Hole
Physical Oceanography Department. ’Once it does, it can take hundreds of years
to reverse.’ And he is alarmed that Americans have yet to take the threat
seriously. D A drop of 5 to 10 degrees entails much more
than simply bumping up the thermostat and carrying on. Both economically and
ecologically, such quick, persistent chilling could have devastating
consequences. A 2002 report titled Abrupt Climate Change: Inevitable Surprises
produced by the National Academy of Sciences, pegged the cost from agricultural
losses alone at $100 billion to $250 billion while also predicting that damage
to ecologies could be vast and incalculable. A grim sampler: disappearing
forests, increased housing expenses, dwindling freshwater, lower crop yields,
and accelerated species extinctions. E Political changes
since the last ice age could make survival far more difficult for the world’s
poor. During previous cooling periods, whole tribes simply picked up and moved
south, but that option doesn’t work in the modern, tense world of closed
borders. ’To the extent that abrupt climate change may cause rapid and extensive
changes of fortune for those who live off the land, the inability to migrate may
remove one of the major safety nets for distressed people,’ says the
report. F Isn’t the earth actually warming Indeed it is,
says Joyce. In his cluttered office, full of soft light from the foggy Cape Cod
morning, he explains how such warming could actually be the surprising culprit
of the next mini-ice age. The paradox is a result of the appearance over the
past 30 years in the North Atlantic of huge rivers of freshwater—the equivalent
of a 10-foot-thick layer—mixed into the salty sea. No one is certain where the
fresh torrents are coming from, but a prime suspect is melting Arctic ice,
caused by a buildup of carbon dioxide in the atmosphere that traps solar
energy. G The freshwater trend is major news in
ocean-science circles. Bob Dickson, a British oceanographer who sounded an alarm
at a February conference in Honolulu, has termed the drop in salinity and
temperature in the Labrador Sea—a body of water between northeastern Canada and
Greenland that adjoins the Atlantic—’arguably the largest full-depth changes
observed in the modern instrumental oceanographic record’.
H The trend could cause a little ice age by subverting the northern
penetration of Gulf Stream waters. Normally, the Gulf Stream, laden with heat
soaked up in the tropics, meanders up the east coasts of the United States and
Canada. As it flows northward, the stream surrenders heat to the air. Because
the prevailing North Atlantic winds blow eastward, a lot of the heat wafts to
Europe. That’s why many scientists believe winter temperatures on the Continent
are as much as 36 degrees Fahrenheit warmer than those in North America at the
same latitude. Frigid Boston, for example, lies at almost precisely the same
latitude as balmy Rome. And some scientists say the heat also warms Americans
and Canadians. ’It’s a real mistake to think of this solely as a European
phenomenon,’ says Joyce. I Having given up its heat to
the air, the now-cooler water becomes denser and sinks into the North Atlantic
by a mile or more in a process oceanographers call thermohaline circulation.
This massive column of cascading cold is the main engine powering a deep water
current called the Great Ocean Conveyor that snakes through all the world’s
oceans. But as the North Atlantic fills with freshwater, it grows less dense,
making the waters carried northward by the Gulf Stream less able to sink. The
new mass of relatively freshwater sits on top of the ocean like a big thermal
blanket, threatening the thermohaline circulation. That in turn could make the
Gulf Stream slow or veer southward. At some point, the whole system could simply
shut down, and so quickly. ’There is increasing evidence that we are getting
closer to a transition point, from which we can jump to a new state. Small
changes, such as a couple of years of heavy precipitation or melting ice at high
latitudes, could yield a big response,’ says Joyce. J
’You have all this freshwater sitting at high latitudes, and it can literally
take hundreds of years to get rid of it,’ Joyce says. So while the globe as a
whole gets warmer by tiny fractions of one degree Fahrenheit annually, the North
Atlantic region could, in a decade, get up to 10 degrees colder. What worries
researchers at Woods Hole is that history is on the side of rapid shutdown. They
know it has happened before. —Discover Magazine