Geology Reference
In-Depth Information
It was a fortunate choice for discussing the future, as changes were occurring immediately
outside our conference center at the cozy Arctic Hotel. For a thousand years, the harbor,
located near the calving front of the mighty Ilulissat Glacier, had served as a rich fishing
ground. For a thousand years, the fishermen resorted to ice fishing in the winter as the har-
bor froze solid every year. Until the new millennium, that is. In 2000, for the first time (at
least in a thousand years of oral history), the harbor was open and unfrozen. The mighty
glacier,aUnitedNationsheritagesite,hasbeenrecedingatanastonishingrate—almostsix
miles in three years after many decades of stability. Another change: for a thousand years
Ilulissat and nearby native villages had been free of insect pests, but in 2007 and all subse-
quent years, an infestation of mosquitoes and black flies arrived in August. These are an-
ecdotes, to be sure, but so too are they unambiguous harbingers of significant, inexorable
change.
Across the globe, similar changes are occurring. Watermen on the Chesapeake Bay re-
port consistently higher high tides than a few decades ago. Year by year the northern Saha-
ra Desert is pushing ever farther north, turning once fertile Moroccan farmland into dust.
Antarctic ice shelves are melting and breaking off at increased rates. Average global air
and water temperatures are on the rise. It's all part of a consistent pattern of warming—a
pattern that Earth hasexperienced countless times inthepastandwill experience countless
times in the future.
Warming can have other, sometimes paradoxical effects. The Gulf Stream, the great
ocean current that carries warm water from the Equator to the North Atlantic, is powered
by the strong temperature differences between the Equator and higher latitudes. If global
warming reduces that temperature contrast, as some climate models suggest, then the Gulf
Stream may weaken or even stop. Ironically, an immediate consequence would be to make
the British Isles and northern Europe, where climate is moderated by the Gulf Stream,
much colder than it is today. Other ocean currents—for example, those from the Indian
Ocean to the South Atlantic past the Horn of Africa—would be similarly affected and
might cause a similar shift in the mild South African climate or a change in the monsoon
rains that keep parts of Asia wet and fertile.
As ice melts, the seas rise. Some sober projections suggest increases of as much as two
or three feet in the next century, though much faster increases of several inches per dec-
ade may have occurred from time to time according to the recent rock record. Such a sea
change will affect many coastal residents around the world and may cause headaches for
civil engineers and beachfront property owners from Maine to Florida, but a few feet is
probably manageable in most populated coastal areas. For a while, for a generation or two,
most residents really won't have much to worry about when it comes to encroaching sea-
water.
