November 12, 2009
Younger Dryas Mini Ice Age Started Quickly
William Patterson of the University of Saskatchewan, says the Younger Dryas mini Ice Age came on in a matter of months.
JUST months - that's how long it took for Europe to be engulfed by an ice age. The scenario, which comes straight out of Hollywood blockbuster The Day After Tomorrow, was revealed by the most precise record of the climate from palaeohistory ever generated.
Around 12,800 years ago the northern hemisphere was hit by the Younger Dryas mini ice age, or "Big Freeze". It was triggered by the slowdown of the Gulf Stream, led to the decline of the Clovis culture in North America, and lasted around 1300 years.
Can our climate suddenly change drastically? Yes. We can't be assured of only slow gradual changes. Most of the time only slower changes happen. But rapid climate change is possible. For this reason I think we should develop the means to alter the climate on a global scale. We might some day need to reverse either a natural or human-made shift in climate.
The Younger Dryas also ended abruptly in 10 years.
Around 15,000 years ago, the Earth started warming abruptly
after ~ 100,000 years of an "ice age"; this is known as a glacial
termination. The large ice sheets, which covered significant parts of North
America and Europe, began melting as a result. A climatic optimum known as
the "Bölling-Allerød" was reached shortly thereafter,
around 14,700 before present. However, starting at about 12,800 BP, the Earth
returned very quickly into near glacial conditions (i.e. cold, dry and windy),
and stayed there for about 1,200 years: this is known as the Younger Dryas
(YD), since it is the most recent interval where a plant characteristic of
cold climates, Dryas Octopetala, was found in Scandinavia.
The most spectacular aspect of the YD is that it ended extremely
abruptly (around 11,600 years ago), and although the date cannot be known
exactly, it is estimated from the annually-banded Greenland ice-core that
the annual-mean temperature increased by as much as 10°C in 10 years.
That's an 18 F warming in ten years. Imagine your local climate changing that much that quickly.
Update: Some scientists think the Younger Dryas cooling was brought on by the bursting of the boundaries of a massive fresh water lake whose waters diluted the salt waters of the northern Atlantic Ocean and stopped the Gulf Stream. Therefore some argue we have no comparable plausible condition that can happen today to cause an equally sharp shift in climate. However, a massive upper atmosphere explosion of an asteroid is another possible explanation for the Younger Dryas. Such an asteroid collision with the Earth is certainly within the realm of the possible.
More generally, I think people have been lulled into complacency by a 20th century whose natural disasters were pretty mild. A century more like the 19th century is within the realm of the possible.
"That's an 18 F warming in tens years. Imagine your local climate changing that much that quickly."
Mine does that every year!!! -20F in the winter to 100F in the Summer.
We adapt ....
"The Younger Dryas was brought about when a glacial lake covering most of north-west Canada burst its banks and poured into the North Atlantic and Arctic Oceans"
Not much chance of that happening now.
"Not much chance of that happening now."
I remember reading that under much of the Greenland ice sheet is a large lake of fresh water. There was some belief that the Younger Dryas could be repeated if that freshwater were to escape from under the ice sheet.
It was a long time ago that I read this, and I think much of it was speculation at the time. Does anyone know if there is truth to it?
"Imagine your local climate changing that much that quickly."
What happened? Is that when they invented SUVs? Everybody knows that the climate doesn't change unless there is human intervention.
random, if the Greenland ice sheet melted, it would be bad. But Greenland has been this warm before .... at least in the 20's and the time of the Vikings, and most likely other times as well.
"We have analyzed temperature time series from available Greenland locations and we have found that:
 i) The years 1995 to 2005 have been characterized by generally increasing temperatures at the Greenland coastal stations. The year 2003 was extremely warm on the southeastern coast of Greenland. The average annual temperature and the average summer temperature for 2003 at Ammassalik was a record high since 1895. The years 2004 and 2005 were closer to normal being well below temperatures reached in 1930s and 1940s (Figure 2).
Although the annual average temperatures and the average summer temperatures at Godthab Nuuk, representing the southwestern coast, were also increasing during the 1995-2005 period, they stayed generally below the values typical for the 1920-1940 period.
 ii) The 1955 to 2005 averages of the summer temperatures and the temperatures of the warmest month at both Godthaab Nuuk and Ammassalik are significantly lower than the corresponding averages for the previous 50 years (1905-1955). The summers at both the southwestern and the southeastern coast of Greenland were significantly colder within the 1955-2005 period compared to the 1905-1955 years.
 iii) Although the last decade of 1995-2005 was relatively warm, almost all decades within 1915 to 1965 were even warmer at both the southwestern (Godthab Nuuk) and the southeastern (Ammassalik) coasts of Greenland.
 iv) The Greenland warming of the 1995-2005 period is similar to the warming of 1920-1930, although the rate of temperature increase was by about 50% higher during the 1920-1930 warming period.
 v) There are significant differences between the global temperature and the Greenland temperature records within the 1881-2005 period. While all the decadal averages of the post-1955 global temperature are higher (warmer climate) than the pre-1955 average, almost all post-1955 temperature averages at Greenland stations are lower (colder climate) than the pre-1955 temperature average.
 An important question is to what extent can the current (1995-2005) temperature increase in Greenland coastal regions be interpreted as evidence of man-induced global warming? Although there has been a considerable temperature increase during the last decade (1995 to 2005) a similar increase and at a faster rate occurred during the early part of the 20th century (1920 to 1930) when carbon dioxide or other greenhouse gases could not be a cause. The Greenland warming of 1920 to 1930 demonstrates that a high concentration of carbon dioxide and other greenhouse gases is not a necessary condition for period of warming to arise. The observed 1995-2005 temperature increase seems to be within a natural variability of Greenland climate. A general increase in solar activity [Scafetta and West, 2006] since 1990s can be a contributing factor as well as the sea surface temperature changes of tropical ocean [Hoerling et al., 2001]."
Has anyone looked into the possiblity that Dr. Evil sent Mini Me in a time machine to Atlantis to extract the Gulf Stream's Mojo?
James, it does seem science fiction movies seem to be source material for the AGW believers/warmenizers.
The President of Woods Hole Oceanographic Institution, Robert Gagosian, has written a pretty good article about the unknowns with regard to Gulf Stream and the Global Ocean Conveyor. My impression from that article and other reading is that we don't know how big a change in salinity and temperature would cause the thermohaline effect to stop.
Since we can't even assign reasonable probabilities it is just one more area of climatology with big unknowns. I'd really like to see an accelerated effort to put buoys in place to measure flows in all the oceans. We really need a much better model of water and heat flow on the planet.
Thomas - my well-educated opinion is that an image from Google does not constitute a scientific proof that a meteorite strike hypothesis is valid. First of all, the image can be of something that looks like a crater, or even of a random geological feature (you can find any message in noise if you look long and squint hard). Secondly, even if it shows an impact crater, there's a question of its age. Thirdly, correlation is not the same as causation.
Bruce - I'd take everything New Scientist prints with a pinch of salt. They are fond of printing all kinds of marginal speculations presenting them as valid scientific theories. Their factual reports (like the one you qouted) are more reliable, but I'd still check. I'll second that "rude idiot" remark, though.
Does anybody know a _decent_ general science periodical? Not an ego (and SCI) inflator like Nature, leaving one to read long reports full of jargon only to ask at the end - so what?, not leftie propaganda mouthpieces like Scientific American and Science (can't read SciAm without wanting to barf... their "science" reporting degraded to the level usually associated with elementary school textbooks, Science is better, but their editorials read like Pravda), and not a scientifically flavored tabloid like New Scientist.
Randall, I think I would worry more about the inevitable tsunami from the azores than I would AGW or abrupt climate change.
"A collapsing volcano could trigger a vast tidal wave capable of wiping New York, Washington and Miami off the map, warn geologists.
They also fear southern England could be hit.
Geologists are concerned that an unstable flank of the Cumbre Vieja volcano on the island of La Palma in the Canaries is in danger of sliding into the sea.
If shaken loose by a volcanic eruption, the huge slab of rock would send a tsunami more than 150 metres high racing across the Atlantic at the speed of a jumbo jet.
Within three hours, the wave would swamp the west coast of Africa, within five hours it would reach southern England and within 12 it would hit America's east coast.
New York, Washington, Boston and Miami would be hit by successive waves abound 20 metres high. Tens of millions of people could die."
I would even worry more about the inevitable asteroid hit ...
"Although no one noticed at the time, the Earth was almost hit by an asteroid last Friday.
The previously undiscovered asteroid came within 8,700miles of Earth but astronomers noticed it only 15 hours before it made its closest approach.
Its orbit brought it 30 times nearer than the Moon, which is 250,000 miles away."
If shaken loose by a volcanic eruption, the huge slab of rock would send a tsunami more than 150 metres high racing across the Atlantic at the speed of a jumbo jet.
Gee, thanks for reminding me. [He types from an elevation of 19m in a remote corner of an island in the Gulf of St. Lawrence.]
I wonder how far I could get within 12 hours with everyone else trying to get to high ground at the same time. Using Google Earth, I see some high ground in Albert County in N.B. at 300m. But, hell, the normal tides near there are 50 ft. Would 300m suffice for a 150m wave after it shoots up the funnel of the Bay of Fundy?
With the traffic, I doubt I could get to any high ground farther away than that because most of eastern N.B. is lower than 100m.
Since I'm about a mile from the Pacific Ocean (but several hundred feet up and also protected by the Channel Islands) I'm not worried personally about the Azores. Though I think people on the East Coast ought to want a better warning system.
Asteroid: Since I can't convince the American people that they should urgently want an asteroid defense system what I want instead is a well-stocked place where I can live underground for a couple of years after an asteroid strike. Since the odds are pretty good I'd survive the initial strike my concern is to survive the ensuing collapse in food production and cold weather.
I wonder if your best bet might be one of the fishing boats in that harbor near you. Is there some place such a boat could go where the speed of the oncoming wave would be slowed?
Albert County NB at 300 m: How far inland is it? How long would it take you to get there assuming no traffic?
In theory you've got a lot more time than people in a lot of other places. People on Caribbean islands are basically screwed unless they are near an airport and react more quickly than anyone else.
"We should develop the means to alter the climate on a global scale"
That's your conclusion? And where does it end? And what makes you think man can alter anything in the scale of the planet? And what makes you think the unintended consequences might not be worst than the original problem?
Maybe we should just let the planet takes its course and try to adapt ourselves, rather than alter the planet. That would be a lot more normal and realistic.
Clearly humans have the largest brains. It's clear they still do not universally know how to apply them, as illustrated by your proposal.
The east coast is not like the west coast. We have a large continental shelf. I don't think a boat would survive a 150m wave here.
On the west coast, if you go straight out to sea, you get to deep water very quickly where the wave is moving a large column of water just a little bit. Given the very large wavelength typical of a tsunami, a boat might survive such a wave in deep water even if it has a crest of 10m or more.
Here on the east coast, you might have to power for half a day to get off the shelf. Because the wave will be in shallower water moving a smaller water column, it will be much closer to the 150m crest that will eventually hit the shore. Suppose it is only 60m, that's still 20 stories high. I think the wave would simply capsize the boat and roll right over top of it. That's if the wave doesn't suck the water out from under the boat before rolling over it.
Without traffic, Albert County would be about 3 hours drive from here. The problem I noted with it is the high ground is only about 10 miles from Alma NB on the Bay of Fundy "Home of the Highest Tides in the World". If the bay amplifies the tide, might it amplify a tsunami? The wave would hit the tip of Fundy later than it hits the coastline elsewhere. How long would I have to stay on high ground before it might be safe to come down again?
The other problem is the communities and larger roads follow the lower elevations. Not only would I have to get to Albert County, but I would have to find my way onto a back road that actually takes me up to high ground. And hopefully not too many other people are smart enough to figure that out so the road isn't totally jammed.
Nature isn't a benign balanced Gaia goddess that we disturb as a bunch of sinners who have fallen out of Eden. Nature is brutal and capricious.
It is uncontroversial that for $2 billion we could bring on another ice age. Producing lots of silicon dioxide to emit into the atmosphere is well within the budgets of many nations, corporations, and rich people to do.
Unintended consequences: Of course there would be. But whether climate engineering would be worth doing would depend on just how far out of whack the climate went. If, for example, the Ocean Conveyor stopped then the consequences would be massive in scope. Huge areas of crop lands would be lost to either drought or cold.
"However, a massive upper atmosphere explosion of an asteroid is another possible explanation for the Younger Dryas. "
Or an extremely strong solar proton event, for which there is a lot more solid evidence than an upper atmosphere explosion of an asteroid. "Evidence for a Solar Flare Cause of the Pleistocene Mass Extinction" June 1, 2011 issue of Radiocarbon (vol. 53 no. 2, pp. 303-323) by Paul LaViolette
Abstract and summary:
The hypothesis is presented that an abrupt rise in atmospheric radiocarbon concentration evident in the Cariaco Basin varve record at 12,837±10 cal yrs BP contemporaneous with the Rancholabrean termination, may have been produced by a super-sized solar proton event (SPE) having a fluence of ~1.3 X 10^11 protons/cm^2. A SPE of this magnitude would have been large enough to deliver a lethal radiation dose of at least 3 - 6 Sv to the Earth's surface, and hence could have been a principal cause of the final termination of the Pleistocene megafauna and several genera of smaller mammals and birds. The event time-correlates with a large magnitude acidity spike found at 1708.65 m in the GISP2 Greenland ice record, which is associated with high NO^-3 ion concentrations and a rapid rise in ^10Be deposition rate, all of which are indicators of a sudden cosmic ray influx. The depletion of nitrate ion within this acidic ice layer suggests that the snowpack surface at that time was exposed to intense UV for a prolonged period which is consistent with a temporary destruction of the polar ozone layer by solar cosmic rays. The acidity event also coincides with a large magnitude, abrupt climatic excursion and is associated with elevated ammonium ion concentrations, an indicator of global fires.
Below is a summary of the paper's principal findings.
• The Pleistocene megafaunal extinction likely had a solar cause.
• An extinction level solar proton event (SPE) likely occurred around 12,837 ± 10 calendar years BP. (This date is based on the varve chronology established for Cariaco Basin ocean sediment core drilled off the coast of Venezuela.)
• The proposed super SPE is estimated to have been roughly 125 times more intense than the February 1956 SPE. On the assumption that its cosmic ray energy spectrum had a hardness comparable to the 1956 event, it is estimated to have produced a ground level radiation exposure ranging from 3 Sieverts (Sv) to over 6 Sv delivered over a two-day period. By comparison, LD-100 (lethal exposure) for most mammals is in the range of 3 to 8 Sv. Lethal dose for humans is 3.5 Sv.
• The magnitude of the super SPE is based on the size of a radiocarbon production spurt registered in the Cariaco Basin radiocarbon excess record. This spurt, which occurs during the early younger Dryas, is one of the two largest to have occurred during the four-millennia-long Cariaco Basin radiocarbon record.
• Correlations made between the Cariaco Basin climate profile and the GISP2 Greenland ice core climate profile show that this candidate radiocarbon spurt correlates with an acidity spike present in the Greenland ice record at a depth of 1708.65 meters, and which is the largest acidity spike to occur during the Younger Dryas period. Also this spike is found to be flanked by two nitrate ion concentration peaks which are the highest of the Younger Dryas period. It is also spanned by a large increase in beryllium-10 concentration. All of these are good indicators for the occurrence of a solar proton event.
• The acidity spike event is found to coincide with a nitrate ion minimum, which indicates that the nitrate ions were photolytically dissociated by exposure to intense UV radiation at the time of their deposition. This strongly suggests that the 12,837 years BP super SPE likely destroyed the polar ozone layer for a period of several years following its impact. This ozone hole may even have extended to mid latitudes allowing harmful UV radiation to penetrate through the Earth's atmosphere.
• Both the high levels of solar cosmic ray radiation and solar UV radiation associated with this event were responsible for the sharp decline in mammal population marked by the Rancholabrean termination which dates close to the time of this event, around 12,883 ± 60 calendar years BP (when converted to calendar years using the Cariaco Basin radiocarbon chronology). This super SPE date also follows the Clovis paleoIndian cut-off date, which lies in the interval 12,880 to 12,840 calendar years BP (Cariaco Basin chronology), and it precedes the black mat stratum at the Murray Springs, Arizona site, which lies between 12,750 and 11,850 Cariaco calendar years BP.
• The 12,837 years BP super SPE was sufficiently large that the main phase decrease produced by its storm time radiation belt ring current could have partially or totally collapsed the geomagnetic field, allowing a large fraction of the impacting cosmic rays to contact the Earth's atmosphere and produce a substantially enhanced particle shower.
• The Greenland ice record suggests that an abrupt climatic cooling occurred at the time of the 12,837 years BP super SPE acidity spike, which is an expected consequence of the generation of high concentrations of condensation nuclei in the stratosphere. The event is also found to be flanked by two very warm episodes separated from one another by about one solar cycle period. The warming following the SPE was one of the most pronounced Dansgaard/Oeschger climatic events of the entire Younger Dryas with polar temperatures reaching Allerod levels. High ammonium ion concentrations, occurring during each of these warm periods, indicate the occurrence of widespread wildfires. Hazards associated with these fires as well as the associated destruction of food supplies and habitats would have been a contributing factor in megafaunal termination.
• A second equally large radiocarbon production spurt is reported to date 12,639 ± 10 calendar years BP, separated by 198 years (one Suess solar cycle or 9 Hale solar cycles) from the primary super SPE event. Also two smaller C-14 spurts are shown to precede the primary event, each separated from one another by three Hale solar cycles. In addition, the GISP2 ice record is shown to record a more minor acidity spike event, i.e., a SPE of lesser intensity, that occurred about 18 years after the primary 12,837 years BP super SPE.
• Lunar rock studies suggest that the Sun was in an unusually active state close to the end of the last ice age. This could explain why these super SPEs were occurring during the terminal Pleistocene and have not occurred more recently.
• In the event that the geomagnetic field would have been substantially disturbed and possibly even temporarily collapsed at the time of SPE and coronal mass ejection impact, large amounts of extraterrestrial dust residing in the circumterrestrial dust sheath would have been consequently jettisoned into the stratosphere. This could account for the extraterrestrial debris-rich layer that has been sporadically reported to underlie the black mat layer in the early YD sediments and the nanodiamond rich layer found in Greenland ice. The comet impact scenario proposed by Firestone et al. to account for this layer is unlikely to have occurred since it has been reported that a comet impact should have produced a nitrate ion signal 10^5 times higher than the upper limit observed in the Greenland ice record.