From the UNIVERSITY OF TEXAS AT AUSTIN
Researchers at The University of Texas at Austin have found that a well-known period of abrupt climate change 12,000 years ago occurred rapidly in northern latitudes but much more gradually in equatorial regions, a discovery that could prove important for understanding and responding to future climate change.
The research, published Sept. 2 in Nature Communications, focuses on the Younger Dryas, a cooling period that started when the North Atlantic Current, an ocean current, stopped circulating. The event caused Earth’s northern hemisphere to enter into a deep chill, with temperatures in Greenland dropping by approximately 18 degrees Fahrenheit in less than a decade.
The event also caused rainfall to decrease in places as far away as the Philippines. However, whereas temperatures in Greenland responded quickly to the ocean current shutdown and subsequent reboot 1,000 years later, it took hundreds of years for rainfall in the Philippines to be affected and to recover.
“We found that the temperature in Greenland is like a small ship that you can stop and turn quickly because of the influence of sea ice in the region, while rainfall in the tropics is like a big ship that takes a long time to course correct,” said Jud Partin, a research associate at the University of Texas Institute for Geophysics (UTIG) who led the study.
The changes in temperature and rainfall are linked to a common cause: the slowdown of the ocean currents in the North Atlantic, which affect climate and temperature as they move warm water from the Gulf of Mexico toward the Arctic. As the world warmed after the last ice age, glaciers melted and diluted northern seawater with freshwater. The resulting change in ocean water density disrupted the current and, in effect, the climate, causing a period of global cooling.
The event also inspired the premise of the 2004 disaster flick “The Day After Tomorrow,” which exaggerates the speed and strength of the cooling by depicting the planet entering an ice age in a matter of weeks after the ocean current collapses.
Although other studies well document the changes in temperature and precipitation around the world, this new study concludes that these changes do not occur or recover at the same rate, as had been previously assumed.
Understanding the relationship between temperature and precipitation in the wake of climate change is particularly important because it previews what could happen if the planet’s ice sheets continue to lose mass and add freshwater to the North Atlantic.
At a conference in Paris during July of more than 2,000 climate scientists, the potential collapse of the North Atlantic Current’s circulation was identified as a possible catastrophic consequence of climate change.
“A slowdown of the ocean circulation is a double-edged sword: If we see some temperature changes associated it … and somehow are quick to act and alleviate the change, then we have the potential to stop it before it impacts rainfall globally,” Partin said. “The longer the circulation event lasts means that it will take that much longer for rainfall to recover.”
The researchers discovered how rainfall in the Philippines was affected by the Younger Dryas event by analyzing minerals deposited in a stalagmite growing from the floor of a cave in Puerto Princesa Subterranean River National Park in Palawan. They found that it took more than 550 years for drought conditions to reach their full extent in the region, and about 450 years to return to pre-Younger Dryas levels after the North Atlantic Current began circulating again. The record suggests rainfall was about 25 percent lower than present levels during the cold snap.
They then compared these findings with previously published ice core data. According to these records, it took a decade or less for temperatures in Greenland to drop by approximately 18 degrees Fahrenheit once the current collapsed and about 40 years to rebound after it returned.
Partin conducted the work with UTIG Director Terry Quinn and collaborators from the National Taiwan University and the University of the Philippines-Diliman. UTIG is a research unit of The University of Texas at Austin Jackson School of Geosciences.
Computational models of the Younger Dryas temperature and precipitation also provided insight into the role of sea ice in Greenland’s abrupt temperature change.
“Sea ice around Greenland acts as a ‘switch,’ causing that region to respond more quickly than the rest of the planet does by insulating the air from heat stored in the deep ocean,” said Yuko Okumura, a UTIG research associate and a co-author on the study.
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The study was funded by a grant from the National Science Foundation.
They keep avoiding all the evidence. Before the last advance of ice, there were mammoths feeding on flowers in the northern latitudes. The mammoths and all other animals and trees were shredded apart by extremely high winds and some were frozen solid with their last, undigested meal in their stomach. The ice spread rapidly and the North Atlantic circulation shut down as a result, not as a cause.
The mechanism that drove this sudden change was an anomalous buildup of heat in the Atlantic ocean, which drove the Gulf Stream clear up to the Labrador and Norwegian seas. The heated waters at such high latitudes created an intense polar vortex, with two major super hurricanes operating simultaneously. At the high latitude, where the atmosphere is considerably shallower, the heat columns from the hurricanes punctured the upper atmosphere and pumped large quantities of heat in the form of infrared radiation into space. The leftover moist air was super cooled and fell to the Earth as ice. The momentum of the storms were so great, they created a mountain of ice over ten miles high that dented the Earth’s crust causing volcanic ruptures in Massachusetts, Connecticut, and Pennsylvania while also sending enormous rivers of ice flowing across the North American continent and all the way down to Illinois.
Enough of this crap about North Atlantic ocean currents causing the Ice Age, the sudden halt of circulation was the result of the Ice Age.
@David Thomson
You don’t believe some phenomena have both a cause and effect on other phenomena?
. . . When the climate STOPS changing, THEN we should start worrying !!!!
“At a conference in Paris during July of more than 2,000 climate scientists, the potential collapse of the North Atlantic Current’s circulation was identified as a possible catastrophic consequence of climate change.”
Well they have misunderstood the fundamental dynamics then. Increased forcing of the climate (positive NAO/AO) increases AMOC rates, and certainly will not promote the any growth of ice shelves that could disrupt ocean overturning at the Achilles Heel of the North Atlantic below Greenland.
I think if one subscribes to the Arctic Iris Effect theory(as I do) this takes away from the importance of the role the AMOC/NAO-AO relationship may play in the resultant Arctic temperature trends.
Time will tell but if this theory is correct and the heat ventilation from the Arctic Ocean subsides partly due to the solar insolation trends going forward then the Arctic is going to cool despite the AMOC /NAO relationship.
The Arctic Iris Effect theory explains abrupt climate change and the random nature of D/O events and why the magnitude of these D/O is greater during glacial times versus non glacial times while nevertheless still being present in the non glacial times at a much reduced magnitude.
I was never sold on the 1470 year semi quasi climate cycle per say and the last 20,000 years of the historical climatic record supports this in my opinion ,although I do believe in a semi loose climate cycle due to Land/Ocean Arrangements, Initial State Of The Climate -Ice Dynamic, Milankovitch Cycles, Geo Magnetic Field Strength, with Solar Variability superimposed upon these climatic items..
That is not to say the AMOC /NAO relationship may not play any role at all. One has to be careful in the elimination or total embrace of any one theory, especially those that has the single cause and effect which is what climate scientist consistently try to do. It is very likely a combination of factors and maybe for example the resultant Arctic temperature trends going forward is a greater combination of factors then even just the Arctic Iris Effect , or the AMOC/NAO relationship theories combined ,let alone these two theories not inclusive of one another although I think the Arctic Iris Effect has the most merit and probably the greatest overall impact on the Arctic temperatures for my money.
One fact that I am certain of is, it is not the warming surface air temperatures which has caused the thinning of the sea ice , but rather the other way around as this Arctic Iris theory suggest.
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A useful corrective to information on this forum: http://wottsupwitthat.com
warrenlb flubbed the link; replace the 2nd letter of the host’s url with an ‘o’ and you’ll go where warrenlb wants you to go, but I’m not going to do his work for him.
Good catch. Here’s the link: http://wottsupwiththat.com/
What does that have to do with anything relevant?
Please do as repeatedly asked and explain how AGW can possibly exist when rising CO2 coincided with global cooling from 1945 to 1977 and again from 2005 until now, which cooling was preceded by flat temperatures from 1997 to 2004.
Thanks!
A totally discredited load of bull ordure which has been left to rot since 2015/02/24, of course.
Your advocacy of such a sad, worthless unscientific effort clearly shows you really haven’t a clue.
What a sad, bitter little specimen you are.
unless someone has found this…
http://www.giss.nasa.gov/research/news/20011119/
From 2001 eh?
So bang up to date then…
Another thought .. relative to ending ice ages…
When we approach ‘snowball earth,’ some of the ocean’s water is on continents as ice. The normally used estimate is that during the last ice age, ocean levels were more than 100 meters lower than at present. It has been theorized that methane formed from decaying biological material deposited in the oceans as clathrates, which decomposed rather quickly when the hydro static head declined sufficiently.
Sound plausible. Methane is a wonderful greenhouse gas.
Except the sea level is low for 90+K years, is that a rather quick decomposition?
“A slowdown of the ocean circulation is a double-edged sword: If we see some temperature changes associated it … and somehow are quick to act and alleviate the change, then we have the potential to stop it before it impacts rainfall globally,” Partin said. “The longer the circulation event lasts means that it will take that much longer for rainfall to recover.”
This is the funniest part as we have absolutely no chance of preventing something like this from happening ever. First you have to make km’s of ice, place them over Canada and parts of USA and then melt trillions of gallons of water into the North Atlantic ocean. It is therefore impossible to prevent a scenario that occurred with conditions that the planet no longer has. The change was huge around North Atlantic Ocean, Iceland and Western Europe. The UK would have ice flows going up against it’s western coast even in Summer. Polar arctic waters were to the western side, with temperatures that resemble what are seen around Southern Greenland’s coast now.
Here’s some actual science being practiced by paleoclimatologists, a rarity these days (the YD has been called HE 0):
http://www.nature.com/ngeo/journal/v7/n2/full/ngeo2045.html
Nature Geoscience | Article
Muted change in Atlantic overturning circulation over some glacial-aged Heinrich events
Jean Lynch-Stieglitz, Matthew W. Schmidt, L. Gene Henry, William B. Curry, Luke C. Skinner, Stefan Mulitza, Rong Zhang & Ping Chang
Heinrich events—surges of icebergs into the North Atlantic Ocean—punctuated the last glacial period. The events are associated with millennial-scale cooling in the Northern Hemisphere. Fresh water from the melting icebergs is thought to have interrupted the Atlantic meridional overturning circulation, thus minimizing heat transport into the northern North Atlantic. The northward flow of warm water passes through the Florida Straits and is reflected in the distribution of seawater properties in this region. Here we investigate the northward flow through this region over the past 40,000 years using oxygen isotope measurements of benthic foraminifera from two cores on either side of the Florida Straits. These measurements allow us to estimate water density, which is related to flow through the thermal wind balance. We infer a substantial reduction of flow during Heinrich Event 1 and the Younger Dryas cooling, but little change during Heinrich Events 2 and 3, which occurred during an especially cold phase of the last glacial period. We speculate that because glacial circulation was already weakened before the onset of Heinrich Events 2 and 3, freshwater forcing had little additional effect. However, low-latitude climate perturbations were observed during all events. We therefore suggest that these perturbations may not have been directly caused by changes in heat transport associated with Atlantic overturning circulation as commonly assumed.
“However, low-latitude climate perturbations were observed during all events. We therefore suggest that these perturbations may not have been directly caused by changes in heat transport associated with Atlantic overturning circulation as commonly assumed.”
That’s because there has been no evidence that the Gulf stream paused or stopped during changes in heat transport associated with AMOC. Warm waters were transported further South and East instead of North via the Gulf Stream. A polar ocean gyre that developed prevented this from happening. Therefore climate was able to function near normal in low latitudes only being slightly cooler. (still 1-2 c below normal)
my memory is trying to remind me something of a power generation scheme the euros were promoting years ago. Seems like they were trying to use ocean currents as a massive power source for electric power. oops