Wednesday, November 30, 2005

Nature Magazine: Atlantic Current Is Weakening


By Elaine Meinel Supkis

The most recent study of the Atlantic currents show weakening of the rate of flow. Some scientists have speculated that a slower current could trigger a sudden ice age if all other meteorlogical and solar actions coincide to produce a plunge in the northern jet stream. The debate about this oscillation possibility rages on. Understanding this process is vital for our survival.

From the NYT:
Scientists say they have measured a significant slowing in the Atlantic currents that carry warm water toward Northern Europe. If the trend persists, they say, the weather there could cool considerably in coming decades.

Some climate experts have said the potential cooling of Europe was paradoxically consistent with global warming caused by the accumulation of heat-trapping "greenhouse" emissions. But several experts said it was premature to conclude that the new measurements, being described in the Dec. 1 issue of the journal Nature, meant that such a change was already under way.
A professor at the University of Washington predicted some time ago that dilution of the salt in the heavy downward moving waters coming out of the Arctic basin, thanks to glacial melt of the ice on Greenland especially, would weaken the conveyor belt of the midocean currents and cause the Gulf Stream to slow down or even break down entirely.
Warming, in theory, could stall the salty, sun-heated, north-flowing currents by causing freshwater to build up in high-latitude seas as ice melts and more precipitation falls.

The scientists, from the National Oceanography Center in Britain, measured sea temperature, currents and other conditions across the Atlantic from the Bahamas to Africa last year and found a 30 percent drop in the flow of warming waters since a similar set of measurements were taken in 1957.

The team, led by Harry L. Bryden, wrote that that even though they had measurements from only 5 years out of the last 50, the pattern of change seen at various depths supported the idea that the shift was a significant trend and not random variability.

They also cited independent measurements of a long-term decline in the flow of water between some Arctic seas and the North Atlantic as evidence that a slowing of the overall Atlantic circulation was under way.

Here is the present system as it works now. The continents have trapped the cold at the top of the planet where there are few escape routes for the cold water which moves rather forcefully down to the warmer southern waters. The cold waters off of California switch about every 20 years with the El Nino events. We are all familiar with this because of its frequency but there is a similar but much slower cycle that happens in the Atlantic.

Roughly double the time scale, every 70 years or so, it switches from warm to cold, each cycle has distinct characteristics. We are in a warm cycle, indeed, the warm cycles are happening longer and more often the last 200 years. The warm cycle features ferocious hurricanes. Hurricane Epsilon, anyone? We have slid right off the scale this year in both volume and velocity.

The alterations in the climate have had wide ranging effects. From the BBC:
Part of the process is likely to mean more precipitation (hail, rain, sleet and snow) at higher latitudes, and so more water flowing down the rivers.

If the global water distribution changes, this could have important social and economic consequences. An altered hydrological cycle might conceivably have a profound cooling effect on north-west Europe as well.

The American Geophysical Union, publisher of the journal, says: "It could also alter the balance of the climate system itself, such as the Atlantic thermohaline circulation, a kind of conveyor belt.

"Cold water flows southward in the Atlantic at great depths to the tropics, where it warms, rises, and returns northward near the surface.

"This flow helps keep northern Europe at a temperate climate, whereas the same latitudes in North America are sparsely settled tundra or taiga."
There is an Arctic oscillation as well as the El Nino and ANSO.

The upper stratosphere is on a different cycle from the land based effects. A thinning of the statosphere changes the dynamics of the airflow in the arctic. Increases or decreases in solar activity especially variable discharges of great violence from sun spots has a huge effect on the conditions in the upper stratosphere over the Arctic. It is no accident we see fabulous aurora boreali up there when the sun is disturbed.

The researchers at the University of Washington have an excellent article about all this. From UW News:

"This Arctic oscillation seems to be doing things in the last decade or two beyond the range of what it has done earlier in the century," he said.

In a 1995 study published in the journal Science, Wallace suggested that the global warming widely believed to be occurring could be, in part, the result of natural cycles. His work on the Arctic oscillation, paid for in part by a National Science Foundation grant, is altering his view because it includes findings that imply human-induced climate change.

"We are looking at temperature changes over Siberia in the last 30 years that are almost 10 times greater than the global mean temperature rise in the last 100 years," he said.

In addition, significant changes in surface winds over the Arctic might have contributed to the thinning of the polar ice cap that has been reported by scientists with last year's SHEBA (Surface Heat Budget of the Arctic Ocean) project, Wallace said.
I have a brother-in-law in Fairbanks, Alaska. There have been more than a few times he has been warmer than we have down here in NY. They have seen temperatures climb to nearly 90 degrees in summer. Snow comes later and later. As the permafrost becomes temporary frost, the heaving and shifting of the soil causes great damage.
One piece of the puzzle, the researchers said, is the existence of a Southern Hemisphere phenomenon, an Antarctic oscillation, which is virtually identical to its northern counterpart except that the Southern Hemisphere has a stronger vortex, or spinning ring of air, encircling the pole. That's because, unlike in the Northern Hemisphere, there are no large mid-latitude continents like Eurasia to disrupt the circular flow, Wallace and Thompson said.

But the cooling of the stratosphere in the last few decades has caused the polar vortexes in both hemispheres to strengthen in winter. Winds at the Earth's surface also have gained speed, sweeping larger quantities of mild ocean air across the cold northern continents. A modeling study being published in the journal Nature on Thursday by researchers at NASA's Goddard Institute for Space Studies suggests the buildup of greenhouse gases might be contributing to colder temperatures in the polar stratosphere. If that trend continues, the colder temperatures ultimately could produce a hole in the ozone layer like that in the Southern Hemisphere, Wallace said.
All the systems oscillate. This is due very much to our dear sun. The sun isn't a stable star pouring its rays upon us evenly and consistently. It heaves and sighs, sometimes shutting down a few percentages or indulging in protracted spats of energy, cosmic and xrays snapping out to slap at our homeworld.

The earth's atmosphere and especially the oceans even out all this uneven energy but when the gases or the particulate matter changes the amount of sunlight or type of sun rays that enter and how much they bounce around once they hit the earth, this system can and will redistribute energy and excess power in various, ingenious ways which we won't like.

Here is the truly disasterous warm cycle. If this model is correct, it means glaciation over much of the northern hemisphere! Not a pretty picture. My little mountain was crushed under a mile of ice once upon a time! There is no way I want to see that!

From the BBC:

Florida-based scientists monitor the northwards-flowing Gulf Stream, and have found it has remained roughly constant over the last 50 years.

The NOC researchers concentrated on the colder water flowing south; and they found that over the last half century, these currents have changed markedly.

"We saw a 30% decline in the southwards flow of deep cold water," said Harry Bryden.

"And so the summary is that in 2004, we have a larger circulating current [in the tropical Atlantic] and less overturning."

And less heat, then delivered to European shores.
They fear a 4-6 degree fall in temperatures in Europe. If this happens, it will be very bad for Europeans who depend on a benign climate. Humans evolved big brains to cope with the ever increasingly unstable weather cycles of the last 3 million years. We now have computers and scientific equipment to monitor the planet and to plan ahead. Being able to peer into the future and project accurately ahead and to plan for all sorts of possibilities is the only way to survive. Our cleverness must be used to make smart choices, not stupid choices.

Just like the obvious geological condundrums of the Hubbert Oil Peak projections, we must understand and take measures to deal with these matters if we want to pass on some sort of civilization to our future progeny. Living recklessly today is futile.

One thing many people forget is how any event can tip all these harmonic cycles into disasters. One obvious candidate for mass wreckage is our sun. It, after all, is the ultimate force moving events in the first place. But we cannot forget volcanoes. The earth goes into various active phases, too. The magnetic orientation changes from north to south and is in fact in the middle of doing exactly that right now. The earth goes through this 150 million year cycle of shoving all the land masses together and then breaking them apart again. We are in the middle of the beginning to jam them all into one mass again, look at how India has crashed into Asia and how Australia is waltzing its Matilda across the Pacific to slam into Japan! And these events create volcanic eruptions. Spectacular ones like the Dacca flows or the Siberian events or our own Yellowstone blow-out.

A volcanic eruption in Indonesia 72,000 years ago nearly annihilated all humans! We had to be very smart and very aware to survive that disaster. Thus, the big brains.

Speaking of brains, here is another delightful story about our genius, Bush. From CNN:
U.S. officials told a U.N. conference on climate change that their government was doing more than most to protect the Earth's atmosphere.

In response, leading environmental groups blasted Washington for refusing to sign the Kyoto Protocol, a global treaty that aims to reduce greenhouse gas emissions.

Canada opened the 10-day U.N. Climate Control Conference on Monday, with about 10,000 experts from 180 nations, to brainstorm on ways to slow the effects of greenhouses gases and global warming. The conference aims to forge new agreements on cutting poisonous emissions, considered by many scientists to be the planet's most pressing environmental issue.

Dr. Harlan L. Watson, senior climate negotiator for the U.S. Department of State, said that while President Bush declined to join the treaty, the U.S. leader takes global warming seriously. He noted greenhouse gas emissions had actually gone down by .8 percent under Bush.
Wow. 0.8%! Way to go! Of course, we were expected, back in the mid nineties, to start reducing it 20% by now! But one tiny step for a moron is one giant step off the cliff for mankind!

I got to get to work on my igloo building skills.

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