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Fw: When the Ice Melts - Everything Changes

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  • Pat N self only
    ... When the Ice Melts - Everything Changes By the Green Hornet Tuesday, August 23, 2005 Last
    Message 1 of 1 , Aug 23 9:09 AM
      ---------- Forwarded Message ----------
      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
      the coastline."

      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
      Gulf Stream.

      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
      world occurs.

      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
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