ABRUPT CLIMATE CHANGE: Records preserved in a Greenland ice core reveal that weather patterns can shift permanently from one year to the next.
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Roughly 14,700 years ago the weather patterns that bring snow to Greenland shifted from one year to the next—a pattern of abrupt change that was repeated 12,900 years ago and 11,700 years ago when the earth’s climate became the one enjoyed today—according to records preserved in an ice core taken from the northern island. These speedy changes—transitions from warming to cooling and back again—in the absence of changes in greenhouse gas could presage abrupt, catastrophic climate change in our future.
"What made these abrupt climate changes were circulation changes, and these changes took place from one year to the next more or less," says glaciologist Sune Olander Rasmussen of the Centre for Ice and Climate at the University of Copenhagen, who was part of a team that analyzed annual data from ice tubes extracted from as deep as 10,000 feet (3,085 meters) beneath the ice sheet, which were collected by the North Greenland Ice Core Project, a drilling expedition.
The researchers looked at three variables in the core: the amount of dust, the kind of hydrogen and the kind of oxygen in the ice. The amount of dust from year to year reveals that less of the grit traveled all the way to Greenland from the deserts of Asia (where the dust that settles over Greenland originates) around the time these transitions began, the team reports in Science.
"If things are starting to change in the dust first then we are looking for a [climate change] trigger somewhere outside of Greenland," Rasmussen says. "That could be monsoon changes," since different rainfall patterns in Asia would affect dust levels in the atmosphere.
Roughly five years after this change in dust levels, the levels of heavy hydrogen ensconced in the ice indicate that weather patterns were shifting and driving precipitation over Greenland that had originated in evaporated water from a different area of the ocean than had previously been the source of the island’s rain. And this change happened in as little as a year. "During the glacial period, abrupt warmings show change of the atmospheric circulation from year to year," says glaciologist Dorthe Dahl-Jensen, also of the University of Copenhagen, who participated in the study as well.
Following this abrupt shift, as much as 20 degrees Fahrenheit (10 degrees Celsius) of warming occurred over the subsequent decades—a change that ultimately resulted in at least 33 feet (10 meters) of sea-level rise as the ice melted on Greenland.
Greenland can change quickly, even living up to its name, according to another paper in this week's Science. Sediment cores from the ocean show that forests of spruce and even fern grew on Greenland just 125,000 years ago. That means Greenland’s ice sheet—potentially responsible for as much as 75 feet (23 meters) of sea-level rise if it all melts—has grown and shrunk far more frequently than previously known.
"The question that arises from such findings is: How come the Greenland ice sheet at such a low latitude has remained so stable during the present interglacial [period] until now?" says study co-author and geochemist Claude Hillaire-Marcel of the University of Quebec in Montreal. "In view of the past instability—and sensitivity to temperature—of Greenland ice, serious concerns about its future under global warming stress do emerge."
Understanding that threat may require traveling even farther back in time via ice, to the transition to the last such warm period 130,000 years ago—the Eemian—when it was nine degrees F (five degrees C) warmer across Greenland. An ice core, known as NEEM (for North Greenland Eemian Ice Drilling), that could address that question is being extracted now as part of the ongoing International Polar Year. "The circulation changes in a few years. The temperature change is happening over decades," Rasmussen notes. "The more we force a system, the more likely it is that we will get some kind of response that is violent."
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13 Comments
Add CommentIt would appear that Bush has had predecessors that like him destroyed the climate in the past. Will we never learn?
Reply | Report Abuse | Link to this"Records preserved in a Greenland ice core reveal that weather patterns can shift permanently from one year to the next." Well I think this phrasing is a little, lets say, off; weather shifting one year to the next is not permanent.
Reply | Report Abuse | Link to thisThe headline editor might have been better served by a word such as persist or endure.
Reply | Report Abuse | Link to thisScientist are exposing the climate change
Reply | Report Abuse | Link to thisScientists have exposed the flaws in the global warming hysteria. Now they are speaking out:
Reply | Report Abuse | Link to thishttp://www.telegraph.co.uk/news/worldnews/2053842/Scientists-sign-petition-denying-man-made-global-warming.html
Here is another link to more details:
http://scienceandpublicpolicy.org/videos/
I read elsewhere that Greenland could be responsible for as much as 5 meters of sea level rise, but that much of that increase would likely be offset by accumulation in East Antarctica. Similarly, the West Antarctic ice sheet is also potentially responsible for 5 meters of sea level rise. This is the primary area of concern because scientists believe that it could collapse rather quickly (a few centuries). East Antarctica would be responsible for an estimated 70 meters of sea level rise, but like Greenland, it is bounded by mountains on all sides and cannot easily slide off into the sea.
Reply | Report Abuse | Link to thisReference: http://www.radix.net/~bobg/faqs/sea.level.faq.html
Furthermore, I have also read that part of Greenland under its ice sheet is 500m below sea level. If ice is 90% the density of seawater, It would take about 110m of ice to melt to fill a 100m basin with water. Part of the Greenland ice sheet already displaces seawater and will not affect sea level.
Abrupt climate change is a little know phenomena, unseen by mankind in recorded history. Same goes for rapid ecosystem collapse:
Reply | Report Abuse | Link to this"Leemans and Eickhout (2004) found that adaptive capacity decreases rapidly with an increasing rate of climate change. Their study finds that five percent of all ecosystems cannot adapt more quickly than 0.1 C per decade over time. Forests will be among the ecosystems to experience problems first because their ability to migrate to stay within the climate zone they are adapted to is limited. If the rate is 0.3 C per decade, 15 percent of ecosystems will not be able to adapt. If the rate should exceed 0.4 C per decade, all ecosystems will be quickly destroyed, opportunistic species will dominate, and the breakdown of biological material will lead to even greater emissions of CO2. This will in turn increase the rate of warming" --Leemans and Eickhout (2004), "Another reason for concern: regional and global impacts on ecosystems for different levels of climate change," Global Environmental Change 14, 219228
We have warmed 0.2 C/decade for the last two decades.
"Few seem to realise that the present IPCC models predict almost unanimously that by 2040 the average summer in Europe will be as hot as the summer of 2003 when over 30,000 died from heat. By then we may cool ourselves with air conditioning and learn to live in a climate no worse than that of Baghdad now. But without extensive irrigation the plants will die and both farming and natural ecosystems will be replaced by scrub and desert. What will there be to eat? The same dire changes will affect the rest of the world and I can envisage Americans migrating into Canada and the Chinese into Siberia but there may be little food for any of them." --Dr James Lovelock's lecture to the Royal Society, 29 Oct. '07
"Abrupt climate change is a little know phenomena, unseen by mankind in recorded history."
Reply | Report Abuse | Link to thisThis simply isn't true. Read up on the Little Ice Age or the Year Without a Summer.
Obviously natural changes occur over time and will vary. Our ability to control the rate of change around a certain set of conditions that people have adapted to is the real concern of Global Warming. Adding fuel to the fire (CO2) and believing it makes no difference and should be ignored because warming has happened before is just plain ignorant and dumb. If Greenland could melt in a few decades and that raises sea levels to dangerous levels, then we should identify the threat and react to it. Pumping GhG into the atmosphere and thinking it doesn't matter, as Spock might say, is not logical. In this day and age you not only have to prove CO2 doesn't matter (which no one has done), you also have to be willing to figure out how to deal with any abrupt natural changes as well. You don't stand in front of a tornado and say, its natural so I don't need to do anything about it. If GhG is a source of warming that we can control, then we should control it regardless of cost.
Reply | Report Abuse | Link to thisThis was an interesting article. The problem with ice melt is that it follows catastrophy math. At 0ºC it takes a further 80 calories input/gram to reach melting point. When that point is reached apparently solid ice just disappears. Heat transference from the surface to the interior of ice caps and glaciers is quite swift as the glaciers are riddled with plumbing. Thus a whole ice feild or glacier can disappear in a season if the internal ice temperatures have been around zero for any length of time. The common worldwide myth of sudden ancestral megaflooding should be a warning to us. Also don't forget that if Greenland looses too much weight it might lurch upwards and cause huge tidal waves.
Reply | Report Abuse | Link to thispeterdunphy51@gmail.com
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Edited by Peter Dunphy at 06/30/2008 5:04 AM
Has anyone thought of this point. The sea level at the equator is dictated by the total volume of the Earth and a degree of spheroidicity dependent upon the rotational speed. Of course the effective diameter of the sea will rise around the polar regions to compensate for the reduced height of land plus ice, but if our rotation speed remains constant, there seems to be no reason for a rise in sea level at the equator.
Reply | Report Abuse | Link to thisSea level diferences are not such an ancient phenomenan. In roman times sea levels were perhaps 2-3 metres higher than present at least in the spanish Guadalquivir River basin with sea navigation over an open lagoon possible as far as Seville in those days. Many other ancient ports around the world have become landlocked as sea levels have been dropping. We have probably reversed the natural process wereby we were slowly slipping into another ice age. If we look at paleo climates some 6000BP we find temperatures similiar to those we enjoy at present and we can expect similiar conditions. The Sahara desert will reduce in size as tropical zones increase north and south, and the Sahara high will shift over the Eastern Mediterrean. Pine forest will spread over the Tundra and there will be an expansion of the temperate zones both North and south with a general increase in rainfall and storm intensity. Mankind will have to move North and inland, luckily the great Eurasian heartland and the Sahara will probably change in our favour. England will become as wet as Ireland and the lower river valleys will become marshes. Alot of coast line will need expensive coastal protection where the cost is justified by large urban infrastructures like London. In London´s case a large storm barrage is already in place and many other large coastal cities will have to follow suit. In my view change is now inevitable but of course we will has always react late. peterdunphy51@gmail.com
Reply | Report Abuse | Link to this"The question that arises from such findings is: How come the Greenland ice sheet at such a low latitude has remained so stable during the present interglacial [period] until now?"
Reply | Report Abuse | Link to thisMust be AGW of course, everything that goes wrong is our fault. Or it could be a natural cycle that has been recorded
across the planet for over 800,000 years. Just accept the
fact that we will have no means to prevent an ice age or a
mega volcano in Yellowstone.