The Little Ice Age:
How Climate Made History 1300-1850
by Brian M. Fagan
PaperbackFloods, Famines, and Emperors:
El Nino and the Fate of Civilizations
by Brian M. FaganThe Long Summer:
How Climate Changed Civilization
by Brian M. Fagan
Posted on 05/08/2005 8:21:59 AM PDT by velyrorenry
CLIMATE change researchers have detected the first signs of a slowdown in the Gulf Stream — the mighty ocean current that keeps Britain and Europe from freezing.
They have found 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 and Europe undergoing a sharp drop in temperatures.
Such a change has long been predicted by scientists but the new research is among the first to show clear experimental evidence of the phenomenon.
Peter Wadhams, professor of ocean physics at Cambridge University, hitched rides under the Arctic ice cap in Royal Navy submarines and used ships to take measurements across the Greenland Sea.
“Until recently we would find giant ‘chimneys’ in the sea where columns of cold, dense water were sinking from the surface to the seabed 3,000 metres below, but now they have almost disappeared,” he said.
“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.”
Such a change could have a severe impact on Britain, which lies on the same latitude as Siberia and ought to be much colder. The Gulf Stream transports 27,000 times more heat to British shores than all the nation’s power supplies could provide, warming Britain by 5-8C.
Wadhams and his colleagues believe, however, that just such changes could be well under way. They predict that the slowing of the Gulf Stream is likely to be accompanied by other effects, such as the complete summer melting of the Arctic ice cap by as early as 2020 and almost certainly by 2080. This would spell disaster for Arctic wildlife such as the polar bear, which could face extinction.
Wadhams’s submarine journeys took him under the North Polar ice cap, using sonar to survey the ice from underneath. He has measured how the ice has become 46% thinner over the past 20 years. The results from these surveys prompted him to focus on a feature called the Odden ice shelf, which should grow out into the Greenland Sea every winter and recede in summer.
The growth of this shelf should trigger the annual formation of the sinking water columns. As sea water freezes to form the shelf, the ice crystals expel their salt into the surrounding water, making it heavier than the water below.
However, the Odden ice shelf has stopped forming. It last appeared in full in 1997. “In the past we could see nine to 12 giant columns forming under the shelf each year. In our latest cruise, we found only two and they were so weak that the sinking water could not reach the seabed,” said Wadhams, who disclosed the findings at a meeting of the European Geosciences Union in Vienna.
The exact effect of such changes is hard to predict because currents and weather systems take years to respond and because there are two other areas around the north Atlantic where water sinks, helping to maintain circulation. Less is known about how climate change is affecting these.
However, Wadhams suggests the effect could be dramatic. “One of the frightening things in the film The Day After Tomorrow showed how the circulation in the Atlantic Ocean is upset because the sinking of cold water in the north Atlantic suddenly stops,” he said.
“The sinking is stopping, albeit much more slowly than in the film — over years rather than a few days. If it continues, the effect will be to cool the climate of northern Europe.”
One possibility is that Europe will freeze; another is that the slowing of the Gulf Stream may keep Europe cool as global warming heats the rest of the world — but with more extremes of weather.
Personally, I think that the enviralists latched onto carbon dioxide as a "cause" of global warming because the planet Venus, which has an extremely hot surface, has an atmosphere of CO2 and sulphur dioxides and they just couldn't help drawing parallels, no matter how full of crap they are.
all that be adjusted for though. If we can figure out how much a star tens of millions lights-years away weighs, I think we can figure that much out.
On balance, I think that the better choice is probably to keep cutting back on particulates and other pollutants. There are valid public health and environmental reasons for doing so, and at this point the biggest economic hit will fall on the horrific smokestacks and air pollution of Russia and Asia.
Im addition to the prospect of cutting CO2 production through cheap, high efficency solar cells becoming possible through nanotechnology, I suspect that the US has some unrevealed global warming options based on secret climate modification research.
The recent drop in atmospheric particulates may be less important to climate change than an apparent natural lessening in cosmic rays and their consequent generation of ions and subatomic particles. Remarkably, these seem to have a crucial role in producing clouds and lightning.
Global warming brings global cooling which will probably bring global warming which in turn will be the forbearer of more global cooling -----and all caused by my car?
Good info on prehistoric CO2, thanks.
I've heard that water vapor can effect temperatures way more than CO2 content. (And I don't doubt that CO2 is negligible.)
Molecule for molecule, water vapor is 80 times more powerful as a thermal agent.
The net effect of major contributers to the greenhouse effect adjusted for atmospheric concentration and thermal characteristics are in the following table
Water Vapor Rules the Greenhouse System
Mankind's impact is only 0.28% of Total Greenhouse effect
http://www.clearlight.com/~mhieb/WVFossils/greenhouse_data.html
Anthropogenic (man-made) Contribution to the "Greenhouse
Effect," expressed as % of Total (water vapor INCLUDED)
Based on concentrations (ppb) adjusted for heat retention characteristics % of All Greenhouse Gases % Natural
% Man-made
Water vapor 95.000% 94.999%
0.001% Carbon Dioxide (CO2) 3.618% 3.502%
0.117% Methane (CH4) 0.360% 0.294%
0.066% Nitrous Oxide (N2O) 0.950% 0.903%
0.047% Misc. gases ( CFC's, etc.) 0.072% 0.025%
0.047% Total 100.00% 99.72
0.28%
And that does not take into account water's capacity to reflect solar radiation away from Earth in the form of Couds and ice.
How can this happen with global warming?
;') I kinda like it -- St Elmo's Fire for the hippie generation.
The Little Ice Age:
How Climate Made History 1300-1850
by Brian M. Fagan
PaperbackFloods, Famines, and Emperors:
El Nino and the Fate of Civilizations
by Brian M. FaganThe Long Summer:
How Climate Changed Civilization
by Brian M. Fagan
The tailgate is the culprit. Nothing like a 4-5' wide and 2' high wind blocker going down the road to whack your mileage.
I seem to remember a study posted here a while back that shows that the tailgate does not serve as a wind blocker. In fact the people who are removing their tailgates (or going to the open net type thingies end up getting slightly lower MPG
The closed tailgate forms a pocket of mostly stagnant air in the bed of the truck. There is little exchange between this pocket and the general airstream flowing over the truck. This causes a decreae in air resistance as the truck does not have to pull the amount of air that it normally would.
A semi pulls behind it a large volume of air as the transition from the large square trailer creates a huge drag zone immediately behind it. On a pickup this drag zone is greater with the tailgate open than with it closed.
Referring to the nascar truck picture earlier on the thread, the closed deck over the bed is intended to decreas drag. And it does. However at normal highway speeds the air exchange between the bed and the airstream is not high enough to need a closed bed.
As an experiment you can do at home place a crumpled up ball of paper (or if you live in the country an empty beer can) in the bed and go for a drive. for most of the ride the ball/can will move around some but it won't leave the bed.
I wish I could remember when the study was posted. I'll try to find it.
Please post it and ping me.
My sons had pickups without camper shells and when they added shells, their mileage increased significantly.
A study from University of Michigan
Both showing decreased MPG due to increased drag from leaving the tailgate down or removing it.
The michagan study touches on this a little. Apparently a lot of the mileage decrease with an open tailgate is due to airstream impact with the bed of the truck. With a shell there is no airstream/bed interaction.
"Remember the story of Moses and the burning Bush"
Too funny. I am going to steal that one!
Greenland Ice Cap Is Melting, Raising Sea Level
Source: The Associated Press
Published: Jul 20, 2000 - 04:05 PM Author: By Paul Recer
Posted on 07/20/2000 14:37:50 PDT by Ms. AntiFeminazi
http://www.freerepublic.com/forum/a3977712e1941.htm
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