Reposted from the Hockey Schtick
A new paper published in Nature Geoscience finds “From about 50,000 to 11,000 years ago, the central Arctic Basin from 1,000 to 2,500 meters deep was … 1–2°C warmer than modern Arctic Intermediate Water.” This finding is particularly surprising because it occurred during the last major ice age.
Horizontal axis is thousands of years ago with modern temperatures at the left and 50,000 years ago at the right. Temperature proxy of the Intermediate Water Layer of the Arctic Ocean is shown in top graph with degrees C anomaly noted at the upper right vertical axis. Note this graph is on an inverse scale with warmer temps at the bottom and colder temps at the top. |
Here’s the paper:
Deep Arctic Ocean warming during the last glacial cycle
T. M. Cronin, G. S. Dwyer, J. Farmer, H. A. Bauch, R. F.
Spielhagen, M. Jakobsson, J. Nilsson, W. M. Briggs Jr &
A. Stepanova
Nature Geoscience (2012) doi:10.1038/ngeo1557
Abstract:
In the Arctic Ocean, the cold and relatively fresh water
beneath the sea ice is separated from the underlying warmer
and saltier Atlantic Layer by a halocline. Ongoing sea ice
loss and warming in the Arctic Ocean have
demonstrated the instability of the halocline, with
implications for further sea ice loss. The stability of the
halocline through past climate variations is unclear.
Here we estimate intermediate water temperatures over the
past 50,000 years from the Mg/Ca and Sr/Ca values of
ostracods from 31 Arctic sediment cores. From about 50 to
11 [thousand years] ago, the central Arctic Basin from
1,000 to 2,500m was occupied by a water mass we call
Glacial Arctic Intermediate Water. This water mass was
1–2°C warmer than modern Arctic Intermediate Water,
with temperatures peaking during or just before millennial-scale Heinrich cold
events and the Younger Dryas cold interval. We use
numerical modelling to show that the intermediate depth
warming could result from the expected decrease in the flux
of fresh water to the Arctic Ocean during glacial conditions,
which would cause the halocline to deepen and push the
warm Atlantic Layer into intermediate depths. Although not
modelled, the reduced formation of cold, deep waters due to
the exposure of the Arctic continental shelf could also
contribute to the intermediate depth warming.
(updated higher quality graph thanks to Roger “Tallbloke”)
Question could the warming come from underwater volcano’s? There has to be some accountable mechanism for bringing this rock out of ice ages.
Interesting. Perhaps the real cause of increased summer ice melt is the reduction in cold fresh water reaching the Arctic Ocean following the damming and diversion of many large rivers in North America and North Asia for agriculture.
When global climate as experienced by surface dwellers, cools, where does the heat go? Down, QED
Viola, Trenberth’s missing heat. Flip the axis upside down aka Mann and the Tijlander series and everything becomes clear. The missing heat is trapped in the past.
Looking at the last ice age glaciation pattern, I can’t help but wonder if the Clovis comet strike shifted the pole from northern Greenland to the middle of the Arctic Ocean. Prior to 11K years ago, this would have put most of the arctic waters further south along with Alaska and Siberian steps to support the mega fauna where they couldn’t have survived today. This study supports that concept.
Chuck Forward
I would look at incoming Arctic currents as the source. If oscillations of trade winds were in the La Nina-like mode in either the Atlantic or Pacific equatorial region for some period of time, this extended season of ocean warming would ride the currents into the Arctic. It may have been the beginning of the end of the glacial cover over the NH.
“Quinx says:
August 29, 2012 at 7:29 am
Interesting. Perhaps the real cause of increased summer ice melt is the reduction in cold fresh water reaching the Arctic Ocean following the damming and diversion of many large rivers in North America and North Asia for agriculture.”
I recall some articles on cyclical current shifts taking water from northern Russian rivers in different directions. Under some current conditions, that fresh water moves east toward the Berring Strait which is a natural chokepoint keeping fresher water in the Arctic making ice formation a lot easier. In the current conditions, that water is flowing west toward the North Atlantic where it disperses more easily and is a smaller influence on a much larger body of water.
This is a interesting find. If this finding pans out, I wonder what its relationship to the Beringia refugia was?
BTW, and some think we understand climate well enough to predict what the moderate increase in the level of a trace gas will have!
I am not surprised the waters would warm under an insulating layer of ice. Remember, the Earth’s crust is producing a lot of heat, especially at the mid-ocean ridges. Heat transfer with from the depths out to space will be reduced when ice is added to the path
As this occurred during an ice age, presumably there would have been rather more (i.e. thicker) ice on the surface than we’re used to. Assuming that the warmth probably originated, then as now, from undersea volcanoes, could it just be basically a case of better ‘insulation’ preventing it from escaping?
When there is ice on top, it stops the heat underneath escaping.
This would suggest that there could be a compensating effect to the loss of albedo arising from less ice.
High latitude precipitation and river flow to the Arctic has increased by about 10% in the last 70 years or so. Alaska broke records last winter. –AGF
Is this statement purely based on their model?
So we are back to “Two Days Before the Day after Tomorrow?” The paper apparently says the warmth is generated by a saltier ocean (less fresh water flows when it is turning into glaciers). An increase in salinity is an increase in density. Temperature will increase to compensate for the density change. The depth will also change where this transition happens.
This finding is particularly surprising because it occurred during the last major ice age.
Inflow of warm heavier salty water from the N. Atlantic’s currents would circulate at some depth below lighter fresh water, while totally frozen surface would prevent any mixing due to tides or storms above; thermo-haline circulation had ideal conditions.
Sorry forgot the link showing vertical distribution of Arctic’s cold and warm currents
http://www.divediscover.whoi.edu/arctic/images/ArcticCurrents-labels.jpg
Uh-oh. Cognitive dissonance found here:
http://www.nodc.noaa.gov/General/NODC-About/Outreach/docs/09/OneNOAASeminar_IPY_John_Walsh.pdf
This above seminar says warmer intermediate layers are responsible for less sea ice in 2007, 2008. The new paper says warmer intermediate layers are seen right before very cold periods.
Hmmm.
From the figure
However, plot B is of delta-18O where the warmer temperatures are on top.
Somehow, I can’t grasp what is being said here, I guess. I thought the laws of thermodynamics sort of required heat to flow from where it is to where it is not. This sort of makes me think that if I could make my attic colder, my floor would be warmer. I don’t quite follow the modeling that makes this work, but I have seen so many “computer models” that leave me breathless that I guess this could just be another one like them. I find it fascinating that science now “knows” facts from so many thousands of years ago by modeling, and interpreting those models. I guess that is one of the driving engines behind “knowing” climate change as well.
yup vuc!
And as we observed this past melt season when the ice is thin storms can induce mixing of the warmer saltier water to the surface where it really does a nice job of melting the ice.
All you have to do is look at bouy data to see the large disturbances the storm caused in the vertical structure of the ocean column.
it’s not surprising that deeper water would be warmer during that period. no open surface no chance to see what we witnessed this season.
Not sure why people think this is surpising. maybe cause the read the word ‘warmer’ and didnt follow what happened during this past storm to the vertical structure.
of course, before the storm hit people at nevens were already explaining what would happen.
and, yup, they were right. ekman pumping. cool stuff. amazing what you can learn if you keep an open mind.
here of course people argued that there would not be a storm. argued that it would have no effect and argued that it was common.. then, of course, they changed their minds about all of that.
now they argue that the storm was rare and that all the ice disappeared because of it. go figure.
There is a lesson in their somewhere
Steven Mosher says:
“here of course people argued that there would not be a storm. argued that it would have no effect and argued that it was common.. then, of course, they changed their minds about all of that.
now they argue that the storm was rare and that all the ice disappeared because of it. go figure.
There is a lesson in their somewhere”
A grammar lesson in “their”, at least. Go figure.
Let me correct Steven’s comment: some people argued some things. But cherry-picking their comments, and then implying that their position is the same as all WUWT readers is a fallacious argument.
Also, the tropical storm/hurricane was a pretty mild one as these things go. The fact that there was landfall resulted in a lot of frantic arm-waving by Chicken Littles. But in reality it was no big deal.
Building on Steven and Vuc:
Solar salt water ponds were develop in the early 80’s by some Israelis, looking at natural formations at hot springs, I believe. The idea is that if you have increasing salinity with depth (usually in steps) you can maintain at the bottom a much hotter body of water than at the top, somewhat contradicting the axiom that hot water rises. By putting these stratified salty layers into a pond with the bottom painted black, solar heat warms the lowest layer, to quite high temperatures like 60 C.
The process of placing salty water from the Atlantic under the cooler water above, with different quantities of water for both, can lead to unexpected warmth trapped at depth.
Disturbing the carefully balanced layers could cause what can be termed disruptive mixing which allows the structure to progressively collapse across a whole region. The result would be a sudden (faster than usual) melting of ice from the untrapping of the heat, followed by a lower than average temperature throughout the water column (because the heat is lost more efficiently from the warmer surface).
To have a 1-2 degree difference over sugh a depth would be easy if the water is slightly saltier (denser). That heat is not collected locally of course, it is imported.
Not sure if it’s possible, but it would be very helpful to have a better image of the chart. that one is so blurry, it cannot be read.
thanks.
DesertYote says:
August 29, 2012 at 8:15 am
BTW, and some think we understand climate well enough to predict what the moderate increase in the level of a trace gas will have!
You should know that scientists know everything. I mean have you ever heard the expression “scientists were amazed to discover”. I thought not.