Fw: When the Ice Melts - Everything Changes
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When the Ice Melts - Everything Changes
By the Green Hornet
Tuesday, August 23, 2005
Last week's column looked at how the gradual heating of the world's
oceans through global warming has become a major threat to islanders
living in the South Pacific � many of whom now have their homes
covered by water. The studies described in that column predicted
substantial and continual rises in the sea level for the next two
centuries, even if we cut way back on our emissions of greenhouse
gases starting now.
The scientists who prepared the studies made it clear that they were
taking into account only the rise in sea level caused by the heating
of the oceans, which causes them to expand (warm water takes up more
room than cold water). What they did not include in their study was
the impact of global warming on the world's icecaps and glaciers,
which are melting at an ever-increasing speed, and its subsequent
impact on sea-level rise.
Several different impacts are predicted to affect both our climate
and the sea level. Just about all of them will affect us here in
Cayman in one way or another.
First, let's take a look at the Arctic ice cap, which has now been
proven by both measurement and observation to be melting faster than
ever before, as recorded temperatures clearly show a warming
scenario. Last week's column was a bit heavy on numbers, one friend
told me, so this week, fewer numbers, more human experience!
Arctic Crossing Abandoned
This year, polar explorers Lonnie Dupre and Eric Larsen have been
forced to abandon their effort to be the first people to make a
summer crossing of the Arctic Ocean, following a series of reversals
largely caused by unseasonably warm conditions in the region. Their
progress northward across the ice was repeatedly interrupted by
frozen leads of water � with ice too thin to ski over and too thick
to paddle through. Early break-up of the ice had created huge
pressure ridges that they were forced to climb, each of them hauling
350 pounds of equipment.
Arctic Ocean currents continually pushed the ice pans on which the
explorers were travelling to the south, even as they struggled to
make progress to the north. Sixteen inches of snow over the course of
just a few days also hindered their progress. (That's not to mention
being frequently harassed by polar bears.)
Because of the changing ice conditions in the region, Dupre believes
that "even winter attempts to the North Pole from here will not be
possible in the near future because of the vast amounts of water off
Both he and Larsen, reports Ocean Update, are looking at other
possible future expeditions, but they "first need to take time to see
if global warming is affecting or altering the conditions elsewhere
on the ocean's rim before we can focus on another project."
It is not just the ice cover that is being affected by global
warming. The animals and people who live in and around the Arctic
Ocean are also having their lives changed. Much has been written
about this already, especially on the lives of the Inuit in Alaska
and northern Canada, and it's easy enough to check on the Web. What I
want to concentrate on is something a little closer to home � the
For those who don't know a lot about the Gulf Stream, it originates
in the Gulf of Mexico and, as the Florida Current, passes through the
Straits of Florida, not that far from us, and follows the coast of
the southeastern United States, extending 50 miles into the Atlantic.
North of Cape Hatteras, it is separated from the coast by a narrow
southern extension of the cold Labrador Current, and from there it
flows northeast into the Atlantic Ocean. Where the warm surface
waters of the Gulf Stream meet the cold winds accompanying the
Labrador Current, one of the densest concentrations of fog in the
Parts of the Gulf Stream current are diverted southeast, forming the
Canary Currents, which carry cooler waters to the Iberian peninsula
and northwestern Africa. An ensuing current, known as the North
Atlantic Drift, flows northwest and provides temperate, relatively
warm waters to Western Europe. The Gulf Stream has an average speed
of four miles per hour but slows down as it widens to the north. At
the beginning of the Gulf Stream, the water temperature is 80�F; the
temperature decreases as the current moves north.
Gulf Stream Slowing
OK, now imagine what would happen if this wide, warm flow of water
were to slow down or even stop. Ice ages are made of the kind of
temperature drop that would be expected if the Earth lost one of its
key circulatory systems. In the 2004 book Feeling the Heat, Jim
Motavalli reported that this slowing-down process has continued
unabated since the last Ice Age, but global warming is throwing in a
monkey wrench by melting ice in the Arctic Ocean. A UN assessment
says Arctic sea ice in summertime could diminish 60 per cent by 2050.
This fresh water could dilute the salinity of the Gulf Stream, which
would mean that it would no longer sink to the bottom of the ocean
near Iceland and begin its return trip to the Pacific.
According to Robert Gagosian, director of the Woods Hole
Oceanographic Institute in Massachusetts, "We're seeing huge
freshening in the North Atlantic. The sinking of the cold, salty
water has slowed 20 percent in the last 30 years."
And now the news. The online edition of the Times of London reported
in May that the Gulf Stream slowdown is no longer theoretical, but is
already occurring. Peter Wadhams, a professor of ocean physics at
Cambridge University, visited the Arctic ice cap on Royal Navy
submarines and discovered "that one of the `engines' driving the Gulf
Stream � the sinking of supercooled water in the Greenland Sea � has
weakened to less than a quarter of its former strength. The
weakening, apparently caused by global warming, could herald big
changes in the current over the next few years or decades.
Paradoxically, it could lead to Britain and northwestern Europe
undergoing a sharp drop in temperatures."
Says Wadhams, "Until recently, we would find giant `chimneys' in the
sea where columns of cold, dense water were sinking from the surface
to the seabed [1.8 miles] below, but now they have almost
disappeared. As the water sank, it was replaced by warm water flowing
in from the south, which kept the circulation going. If that
mechanism is slowing, it will mean less heat reaching Europe."
Dr. Gagosian says that a shutting down of the Gulf Stream would mean
that "average winter temperatures could drop by five degrees
Fahrenheit over much of the United States, and by ten degrees in the
northeastern United States and in Europe. That's enough to send
mountain glaciers advancing down from the Alps; to freeze rivers and
harbors and bind North Atlantic shipping lanes in ice; to disrupt the
operation of ground and air transportation; to cause energy needs to
soar exponentially; to force wholesale changes in agricultural
practices and fisheries; to change the way we feed our populations.
In short, the world, and the world economy, would be drastically
In Nature magazine, the journal of scientific record, Lamont-Doherty
Earth Observatory geochemist Jean Lynch-Stieglitz presented evidence
that the Gulf Stream "operated at about two-thirds its current rate
during the height of the last ice age. This in turn suggests that the
entire oceanic conveyor also slowed, and so moved less heat into the
icy upper latitudes."
Wallace Broecker, senior Lamont-Doherty geochemist and a founding
father of the conveyor model of ocean circulation, comments, "Jean's
work suggests that conveyor circulation virtually stopped during the
last glacial period."
So what's happening today is not unprecedented, but that may be
beside the point. Humans had no effect on the last ice age, but they
are a huge factor in the loss of ocean circulation being measured
today by scientists like Peter Wadhams.
So what, you ask. How will that affect us in the Caymans? So what if
Europe starts to cool down, and when did you last worry about polar
bears, hmm? It might even boost our tourism, all those folks escaping
freezing temperatures in Europe and the U.S.
Look at a couple of impacts. Most severe weather takes place when
cold air and hot air meet. The tropics are getting warmer, Europe and
the northeastern United States and Canada are getting colder. When
air masses over the temperate and tropical zones meet, there will be
more extreme weather. The water that has been locked into Arctic ice
is now merging with the oceans. More water means sea levels rise.
That doesn't even begin to address the impact on the food we eat and
where it is grown (and how it gets here), or the wood we use for
construction. And then there are the increased costs of energy and
transportation systems. So maybe we should start thinking about
growing more of our food now, and importing less.
If you think the Arctic ice is a problem, wait till next week, when
we look at the effects of global warming on the Antarctic!
An independent voice for the Cayman Islands
Posted by Tim