From GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre
Regional climate changes can be very rapid. A German-British team of geoscientists now reports that such a rapid climate change occurred in different regions with a time difference of 120 years. Investigation in the west German Eifel region and in southern Norway demonstrated that at the end of the last glaciation about 12,240 years before present climate became warmer, first recognised in the Eifel region and 120 years later in southern Norway. Nonetheless, the warming was equally rapid in both regions.
The team around Christine Lane (Oxford University) and Achim Brauer from the GFZ German Research Centre for Geosciences reports in the latest volume of “Geology” (vol 41, no 12, p. 1251) that within the younger Dryas, the last about 1100-year long cold phase at the end of the last ice age, a rapid warming first was measured in the Eifel region. Sediment cores from the Meerfelder Maar lake depict a typical deposition pattern, which was also found in the sediments of Lake Krakenes in southern Norway, but with a time lag of 120 years.
But how did the researcher revealed such a accurate time marking? “12 140 years ago a major eruption of the Katla volcano occurred on Iceland” explains Achim Brauer. “The volcanic ash was distributed by strong winds over large parts of northern and central Europe and we can find them with new technologies as tine ash particles in the sediment deposits of lakes. Through counting of annual bands in these sediments we could precisely determine the age of this volcanic ash.” Therefore, this ash material reflects a distinct time marker in the sediments of the lakes in the Eifel and in Norway.
Furthermore, lake sediments are very accurate climate archives, especially when they contain seasonal bands similar like tree rings. “It is a diligent piece of work to count and analyse thousands of these thin layers under the microscope to reconstruct climate year-by-year far back in time”, illustrates Brauer.
The ash of the Katla volcanic eruption thus was deposited at the same time in the Eifel and in Norway. The sediments of the Eifel maar lake depict the rapid warming 100 years before the volcanic ash, while it is seen in the southern Norwegian lake sediment 20 years after the volcanic eruption. The same warming, but with a 120 difference in timing between the about 1200 km distant locations? Achim Brauer:
“We can explain this difference with the shift of hemispheric wind systems. Climate changed in both regions very rapid, but the polar front, that is the atmospheric boundary layer between cold polar air and the warmer air of the mid-latitudes, required more than 100 years to retreat from its glacial position at about the location of the Eifel at 50° N to its southern Norwegian position at 62° N.”
Hence, the study provides evidence for a rapid change that slowly moved northwards. The result of this study has some implications on the understanding of both past and future climate change. The assumption of an everywhere and always synchronously changing climate must be questioned and climate models have to better consider such regional aspects.
C.S. Lane, A. Brauer, S.P.E. Blockley, P. Dulski: “Volcanic ash reveals a time-transgressive abrupt climate change during the Younger Dryas”, Geology v. 41, no. 12, p. 1251 December 2013; doi:10.1130/G34867.1
Photos of the Meerfelder Maar and of lake drilling can be found here: http://www.gfz-potsdam.de/medien-kommunikation/bildarchiv/klimaforschung/warvenchronologie/
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There’s a low frequency “stadium wave” for you.
There must have been a large temperature gradient along that 1,200 Km span leading to some very violent weather.
Nothing new, except maybe a new straw for them to clutch at in an attempt to save their failed models.
DHR says:
December 4, 2013 at 10:04 am
There must have been a large temperature gradient along that 1,200 Km span leading to some very violent weather.
Superstorm CroMagnon must have been a bugger on the Stonehenge waterfront.
I have a feeling that it will get lost in the noise: But what they’re stating is that ‘rapid’ climate change is dependent on the atmospheric convection cells. (Polar/Ferrel/Hadley.) eg. Following the CAGW hypo, then at what ppm of CO2 will we find the widths of each cell doing what?
Hint: The models don’t deal with convection in any reasonable manner.
So they’re using the Katla eruption as a chronological synchronizer, but the 120yr discrepancy raises the idea that there may have been another eruption 120yr later — maybe even from the same volcano. Prevailing wind patterns could have blown the ash of one eruption in one direction, and of the other eruption in the other direction. Check your assumptions, I say to them.
What if one area was still glaciated at the time of the eruption and it then took much longer for the sediment to enter the lake? Sure they cant be accounting for everything!
I wonder if they cross checked the ash assumption with carbon dating of any pollen in the layers immediately above and below the ash layer?
Perhaps there is a chemical signature in individual eruptions from the same volcano that enables them to state the material is definitely from the same eruption? I don’t know if this is possible or not.
NZ Willy’s explanation of two separate eruptions sounds much more plausible. Atmospheric patterns are just not that rigid. I am guessing that none of the authors are forecasting meteorologists…who would know better.
The very assertion that lake bed deposits arriving from hundreds of miles away over whatever time period it takes for erosion, glacial melting, whatever can be assigned a year is unsupportable. Okay, the volcano erupted 12,140 BCE (BP?) but lake deposits can only be younger than that.
The ash of the Katla volcanic eruption thus was deposited at the same time in the Eifel and in Norway.
I doubt the accuracy of the 120 year delay between Germany and Norway.
The ash deposits may be from two rather than a single Katla’s eruption; these are relatively frequent, on average every 50 years during the last 500 years (1999, 1955, 1918, 1860, 1823, 1755-56, 1721, 1660-61, 1625, 1612).
Owen in GA says:
December 4, 2013 at 10:32 am
I wonder if they cross checked the ash assumption with carbon dating of any pollen in the layers immediately above and below the ash layer?
Radio carbon is a bit of a rubber ruler. It can place you in the right ball park, but leave unclear where the seats really are. The Younger Dryas is particularly problematic, and, while there’s considerable debate about this, it seems fairly clear that a large C-14 anomaly (ca. 1,000 years worth) may mark the YD. If so, any C-14 measurement from that period will yield anomalously young dates. Varve counting will usually to be far more reliable, provided the counts are being double checked. Optically stimulated luminescence dating which ought to be somewhat less subject to the environmental vagueries that cause secular variation in geochronological dates is also a possibility. The “gotcha” here is that you and others have been pointing out, these changes are accompanying an abrupt change. Ice sheets are melting, winds are rearranging their delivery routes, etc,
In short, all change occurs at the margin, and the margin can move.
Polar front? Tri cellular model of circulation?
That these authors are still talking of polar front is truly sad. Any observation of atmospheric circulation on satellite imagery over a few days shows that the polar front is a fantasy as cold air masses can penetrate deep toward the equator and even reach it. There is no front stopping them. Thus the meteorological explanation brought up by these author is obsolete and likely wrong. In particular, both cooling and warming can happen at the same time in different palces (even close ones) depending on the trajectories followed by MPHs. It is known that during the onset of the last glaciation, the Svalbard islands were first experiencing warming (likely as a result of being on the path of renewed advection of warm air from colder, higher pressure MPHs that reached farther southward, a warming not dissimilar to Eastern Greenland’s now) until the glaciation progressed to the point of invading these islands.
So the study points toward a shift in circulation yet to be described in detail (likely evolution of the preferred trajectories of MPHs, under what influence?) but it does not unequivocally support their lag time conclusions. A little observation of atmospheric workings from these authors would have gone a long way to offer reality based suggestions in their closing remarks.
Answers to a number or questions raised:
The ash is presumably the well-documented and very widespread Vedde ash which occurs all the way from Switzerland and Great Britain to Carelia. This was an exceptionally heavy and widespread ashfall that occurred in mid-Dryas 3. The date for the end of the Dryas would have been determined by counting annual varves after the ashfall. This is a very well established dating technique in northern Europe that allowed the end of the ice-age to be dated at about ten thousand years ago as early as 1912.
“So they’re using the Katla eruption as a chronological synchronizer, but the 120yr discrepancy raises the idea that there may have been another eruption 120yr later — maybe even from the same volcano. Prevailing wind patterns could have blown the ash of one eruption in one direction, and of the other eruption in the other direction. Check your assumptions, I say to them.
The Vedde ash is unique in that time-range and no trace of a second similar ashfall has ever been found anywhere. If two huge ashfalls had occurred during Dryas you would expect that both would be present somewhere in the huge area where the Vedde ash occurs. However a negative can never be conclusively proven.
” I wonder if they cross checked the ash assumption with carbon dating of any pollen in the layers immediately above and below the ash layer?”
Not practicable. The abrupt changes in the carbon flux at the end of the ice age means that there is a “C-14 plateau” about a thousand years long at that time, so events during Dryas 3 cannot be reliably separated by radiocarbon dating.
“Perhaps there is a chemical signature in individual eruptions from the same volcano that enables them to state the material is definitely from the same eruption? I don’t know if this is possible or not.”
It is often (not always) possible to identify which volcano or volcanic province an ash layer comes from, and in this case the chemical composition makes it virtually certain that the Vedde ash came from Iceland and very likely that it came from Katla/Eldgja.
“What if one area was still glaciated at the time of the eruption and it then took much longer for the sediment to enter the lake? Sure they cant be accounting for everything!”
No problem. The Dryas End Moraines are very conspicuous in Scandinavia. We know exactly which lakes were glaciated and which were not.
”There must have been a large temperature gradient along that 1,200 Km span leading to some very violent weather.
Very likely. The heaviest hurricane ever to hit Bermuda occurred about 100,000 years age during MIS 5c, an interval when tropical and subtropical areas were about as warm as now, but when there was already considerable glaciation in Siberia and Scandinavia.
The Younger Dryas was certainly a very bad period almost everywhere in the northern hemisphere. The forest trees, humans and most large animals that had colonized Southern Scandinavia either went extinct or emigrated while the cold and dry conditions in the Middle East may have been an determining factor in the development of the first primitive agriculture at this time.
“The very assertion that lake bed deposits arriving from hundreds of miles away over whatever time period it takes for erosion, glacial melting, whatever can be assigned a year is unsupportable. Okay, the volcano erupted 12,140 BCE (BP?) but lake deposits can only be younger than that.”
Its BP, and no, loose volcanic ash doesn’t stay around long before it is overgrown or washed away. Some of the ash will land right in the lake to start with and almost all of it will arrive within a year or two. The lowest annual layer to contain the ash will be either the year of eruption, or the year after if the ashfall was in early winter. Did you visit the Pacific Northwest in the 1980’s? If so how long did it take until the ash from Mount St Helens had disappeared?
“The ash deposits may be from two rather than a single Katla’s eruption; these are relatively frequent, on average every 50 years during the last 500 years (1999, 1955, 1918, 1860, 1823, 1755-56, 1721, 1660-61, 1625, 1612).”
Yes but how many of them covered most of northern Europe with ash? None. By the way the 1955 amd 1999 mini-eruptions did not even penetrate the icecap on top of Katla.
This study is ridiculous. As the ice melted, Northern Germany became ice free because it is relatively low lying and flat. Southern Norway however, still has glaciers, Folgefonna and Hardanger and plenty of mountains (6,000 ft) in the Telemark.
At the same time that Northern Germany became ice free there would have been much larger versions of the current Southern Norway glaciers close by and even the Telemark would probably have been under a glacier. Are we to suppose that Southern Norway, glaciers close by, would have the same weather as Northern Germany, no glaciers and 800 miles further south?
PS rapid climate change occurs when the permanent ice in your locality finally all melts.
NZ Willy says:
December 4, 2013 at 10:17 am
—-
Just as plausible, the ash from the same source could have collected on ice remaining at the Norway site and when it melted 120 yrs later it collected at the bottom of the lake.
Barry Cullen says: “Just as plausible, the ash from the same source could have collected on ice remaining at the Norway site and when it melted 120 yrs later it collected at the bottom of the lake.”
No, no, no! Authority “tty” states above that it is all washed away in one to two years. Never mind the US Army Corps of Engineers 33 years after still excavating dozens of feet of ash from navigable rivers near Mt St Helens.
“No, no, no! Authority “tty” states above that it is all washed away in one to two years. Never mind the US Army Corps of Engineers 33 years after still excavating dozens of feet of ash from navigable rivers near Mt St Helens.”
Yes indeed. But neither Norway nor German is “near” Katla. There isn’t a lot of Mt St Helen ash being excavated in Montana or Texas is there (those are at about the right distance) ? Incidentally I know that there was noticeable amounts of Mt St Helen ash in Montana, since I happened to be there about a week after the eruption.
Just as plausible, the ash from the same source could have collected on ice remaining at the Norway site and when it melted 120 yrs later it collected at the bottom of the lake.
Nonsense. Kråkenesvatnet lies on the outer coast, far outside the Dryas 3 end moraines (“raerne” in Norwegian) so there wasn’t any ice in the area at the time, also given the topography, any water from the remaining icecap would have to run uphill across a couple of mountain chains to reach the lake.
This study is ridiculous. As the ice melted, Northern Germany became ice free because it is relatively low lying and flat. Southern Norway however, still has glaciers, Folgefonna and Hardanger and plenty of mountains (6,000 ft) in the Telemark.
At the same time that Northern Germany became ice free there would have been much larger versions of the current Southern Norway glaciers close by and even the Telemark would probably have been under a glacier. Are we to suppose that Southern Norway, glaciers close by, would have the same weather as Northern Germany, no glaciers and 800 miles further south?
Yes, Telemarken was still mostly ice-covered at the time. However Kråkenesvatnet is on the outer coast, at an altitude of about 40 meters, so it is actually a lot lower than Meerfelder Maar at 335 masl (and the difference would have been rather larger at the time because of glacioisostatic effects). However this paper is not about relative climates, but about abrupt climate shifts, such as the end of the Dryas 3 stadial, which is known to have been extremely abrupt everywhere where it has been thoroughly studied.
However it is strange nobody seems to have noticed the real weakness of the paper. As far as I can judge from the press release and the abstract, the event they are referring to is not the end of Dryas 3, but rather the shift from the very cold early part of the stadial to the not quite as cold later part. At least in Scandinavia this was a much less dramatic shift, though it is probably the reason that there are two Dryas end moraines in many areas, and at Kråkenes lake there is about 60 cm of Dryas sediments above this level.
Billy Liar says:
PS rapid climate change occurs when the permanent ice in your locality finally all melts.
Sorry but no. The rapid climate change comes first. By the time the last ice in Scandinavia melted the climate was already a lot warmer than now. In central Sweden pine forest was growing at the top of Mount Åreskutan (1400 meters, way higher than the current treeline) while the valleys below were still ice-covered.
Steve McIntyre has been discussing the uses and misuses of varve thickness and varve counting here: http://climateaudit.org/2013/12/04/more-on-hvitarvatn-varves/
It is worth reading, especially since it touches upon issues being brought up here. Well worth reading.
At the Younger Dryas, wasn’t Norway still completely glaciated. I don’t think there were any lakes in Norway at this time that can accumulate varve sediments.