Slip Sliding Away
Tue Oct 25, 2005 at 06:25:44 PM PDT
chillin' - Liberal Street Fighter
A sobering piece in the NY Times highlights the snowballing (sorry, couldn't resist) damage being caused in the artic by global warming:
At age 73, Dr. Koerner, known as Fritz, still regularly hikes high on the ancient glaciers abutting the warming ocean to extract cores showing past climate trends. And every one, he said, indicates that the Arctic warming under way over the last century is different from that seen in past warm eras.
Many scientists say it has taken a long time for them to accept that global warming, partly the result of carbon dioxide and other heat-trapping gases in the atmosphere, could shrink the Arctic's summer cloak of ice.
But many of those same scientists have concluded that the momentum behind human-caused warming, combined with the region's tendency to amplify change, has put the familiar Arctic past the point of no return.
The particularly sharp warming and melting in the last few decades is thought by many experts to result from a mix of human and natural causes. But a number of recent computer simulations of global climate run by half a dozen research centers around the world show that in the future human influence will dominate.
Even with just modest growth in emissions of the greenhouse gases, almost all of the summer sea ice is likely to disappear by late in the century. Some of the simulations, including those run on an advanced model at the National Center for Atmospheric Research in Boulder, Colo., show much of the summer ice disappearing by 2050, said Marika Holland, a scientist there who is working on the sea-ice portion of that model.
The corpoflack "scientists" that the Republicans like to put forward as experts like to insist that what we are actually seeing are just natural cycles, the same argument used to deny that the recent increase in hurricane severity has anything to do with human impacts on the environment. In typical winger/greedhead fashion, we're presented with a simple minded formulation: it's EITHER a natural cycle OR it's the result of human action. Apparently they have never watched a child push a hula-hoop downhill, where a NATURAL result of gravity is FACILITATED by human action. Too complicated for simple minds, I suppose:
The emerging picture of great Arctic changes ahead comes from the interlaced efforts of the modelers in their climate-controlled computer rooms and field scientists with numb toes and frosted beards. It will long remain a work in progress. But the underlying trends are robust, many Arctic scientists say.
Field work suggests that past Arctic warm spells, like a stretch through the 1920's and 1930's, were limited to certain regions, while the recent warming has largely progressed in concert with rising temperatures around the Northern Hemisphere - a sign of large forces at work, climate scientists say, not regional variability.
Field studies have also provided information on how energy flows from air to ocean and into melting ice, how melting ice freshens water and growing ice makes it saltier - all dynamics that have helped modelers refine their programs.
Recent expeditions on icebreakers have started building the first detailed picture of the communities of algae, plankton, small cod, seals and polar bears that form an ice-based ecosystem as tenuous as the ice itself.
In the virtual Arctic of computer simulations, thousands of lines of computer code mimic how ice, oceans and the atmosphere interact and are components of larger global models of earth's climate and oceans.
The models are the only way to test how the planet may react to various human actions. Because there is only one earth, there are no other options for such studies, given that the real earth is already well along in an unintended experiment - the rapid buildup of long-lived greenhouse gases.
Those who work in that realm have steadily improved their simulations. A decade ago, for instance, most depicted sea ice just as static reflective slabs, and almost all now replicate how ice is tugged by wind and ocean currents, Dr. Holland said.
The inevitability of summer ice retreats, she and other Arctic experts say, is a result of the nature of the climate system, which is something like a heavy flywheel. Once started, flywheels tend to keep going. Within a few decades, say many scientists focused on the region, the insulating power of greenhouse gases will dominate natural climate fluctuations, possibly for centuries.
And the flywheel in the Arctic moves faster than in other areas because the region amplifies change. The most obvious mechanism is the difference in how bright white sea ice and the dark sea act under sunlight. Ice reflects most of the solar energy striking it back into space. Water absorbs most of it.
A result is that each area of ocean exposed by melting ice soaks up heat, melting more ice, exposing more sea, soaking up even more heat - and so on, until the annual marathons held each spring on the floating ice near the North Pole are replaced by boat races.
Of course, many of us wimpy lefties focus on destroyed cultures and species facing extinction. There is, however, if you look at it with the right bloodthirsty eyes, a bright side to these changes:
Even with just modest growth in emissions of the greenhouse gases, almost all of the summer sea ice is likely to disappear by late in the century. Some of the simulations, including those run on an advanced model at the National Center for Atmospheric Research in Boulder, Colo., show much of the summer ice disappearing by 2050, said Marika Holland, a scientist there who is working on the sea-ice portion of that model.
Of the various simulations, all done for an international scientific report on climate trends to be issued in 2007, the only ones that retain much summer sea ice in the Arctic by 2100 are those that assume global greenhouse-gas emissions are held constant at rates measured in 2000 - something that only five years later is already impossible.
The other models all produce an Arctic Ocean in summer akin to the "open polar sea" that was sought by oceanographers and explorers in the mid-1800's. "There would definitely be shipping along the Eurasian coast, and the polar bears would have some serious issues," Dr. Holland said.
Shipping which will most likely produce opportunities for profit. So it's not all bad. Maybe a complete Mastadon skeleton or two will bubble to the suface of the bogs that are forming where there was once permafrost.
Those authors and many other experts have settled on the same picture of the region late this century: tundra retreats and forests spread; most sea ice disappears in late summer; coastlines wear away under the assault of wind-driven waves on waters that previously were sheathed in ice; permafrost turns to bogs; and ancient lakes that once sat atop permanently frozen ground drain like unplugged bathtubs.
Climatologists say the effects eventually could extend far beyond the sparsely populated north, contributing to climate and ocean shifts that could dry the American West and possibly slow north-flowing warm currents in the Atlantic Ocean that keep northern Europe milder than it would otherwise be.
The effects could also include a sharp increase in the rate at which seas are swelled by melting glacial ice and far greater warming as even more greenhouse gases, locked in permafrost and the Arctic seabed, are liberated by warming.
For example, American and Russian scientists studying lakes in northeastern Siberia recently reported that the melt of permafrost is generating methane, a potent greenhouse gas. In spots, so much methane is being released that roiling streams of bubbles prevent the surface from freezing even in the depths of the Siberian winter.
The most that can be expected, some climate scientists say, is to limit the human contribution to warming enough to forestall the one truly calamitous, if slow motion, threat in the far north: the melting of Greenland's ice cap.
Rising two miles high and spreading over an area twice the size of California, this vast reservoir - essentially the Gulf of Mexico frozen and flipped onto land - contains enough water to raise sea levels worldwide more than 20 feet.
In recent years, the ice sheets of Greenland have been building in the middle through added snowfall but melting even more around the edges in summer. Many Greenland experts say the melting is already winning out.
There is more info (LOTS more) available at the Arctic Climate Impact Assessment. In any event, decades of stonewalling by the rightwing and the business community may very well have pushed us past the point of no return. With the ongoing assault on reason, learning, science and higher education, it's liable only to get worse, and attempts to mitigate the damage will also be thwarted.
Dr. Koerner, the Canadian glaciologist, pointed out on time scales of millenniums, the recent warming has even trumped a long cooling trend.
"The warming trend is even more significant," he said, "because it's not on a flat background but something that maybe should be getting colder."
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