From the University of Massachusetts at Amherst and the department of melted evidence, comes this interesting story about the last ice age.
Icebergs once drifted to Florida, new climate model suggests
The first study to show that when the large ice sheet over North America known as the Laurentide ice sheet began to melt, icebergs calved into the sea around Hudson Bay and would have periodically drifted along the east coast as far south as Miami
AMHERST, Mass. – Using a first-of-its-kind, high-resolution numerical model to describe ocean circulation during the last ice age about 21,000 year ago, oceanographer Alan Condron of the University of Massachusetts Amherst has shown that icebergs and meltwater from the North American ice sheet would have regularly reached South Carolina and even southern Florida. The models are supported by the discovery of iceberg scour marks on the sea floor along the entire continental shelf.
Such a view of past meltwater and iceberg movement implies that the mechanisms of abrupt climate change are more complex than previously thought, Condron says. “Our study is the first to show that when the large ice sheet over North America known as the Laurentide ice sheet began to melt, icebergs calved into the sea around Hudson Bay and would have periodically drifted along the east coast of the United States as far south as Miami and the Bahamas in the Caribbean, a distance of more than 3,100 miles, about 5,000 kilometers.”
His work, conducted with Jenna Hill of Coastal Carolina University, is described in the current advance online issue of Nature Geosciences. “Determining how far south of the subpolar gyre icebergs and meltwater penetrated is vital for understanding the sensitivity of North Atlantic Deep Water formation and climate to past changes in high-latitude freshwater runoff,” the authors say.
Hill analyzed high-resolution images of the sea floor from Cape Hatteras to Florida and identified about 400 scour marks on the seabed that were formed by enormous icebergs plowing through mud on the sea floor. These characteristic grooves and pits were formed as icebergs moved into shallower water and their keels bumped and scraped along the ocean floor.
“The depth of the scours tells us that icebergs drifting to southern Florida were at least 1,000 feet, or 300 meters thick,” says Condron. “This is enormous. Such icebergs are only found off the coast of Greenland today.”
To investigate how icebergs might have drifted as far south as Florida, Condron simulated the release of a series of glacial meltwater floods in his high-resolution ocean circulation model at four different levels for two locations, Hudson Bay and the Gulf of St. Lawrence.
Condron reports, “In order for icebergs to drift to Florida, our glacial ocean circulation model tells us that enormous volumes of meltwater, similar to a catastrophic glacial lake outburst flood, must have been discharging into the ocean from the Laurentide ice sheet, from either Hudson Bay or the Gulf of St. Lawrence.”
Further, during these large meltwater flood events, the surface ocean current off the coast of Florida would have undergone a complete, 180-degree flip in direction, so that the warm, northward flowing Gulf Stream would have been replaced by a cold, southward flowing current, he adds.
As a result, waters off the coast of Florida would have been only a few degrees above freezing. Such events would have led to the sudden appearance of massive icebergs along the east coast of the United States all the way to Florida Keys, Condron points out. These events would have been abrupt and short-lived, probably less than a year, he notes.
“This new research shows that much of the meltwater from the Greenland ice sheet may be redistributed by narrow coastal currents and circulate through subtropical regions prior to reaching the subpolar ocean. It’s a more complicated picture than we believed before,” Condron says. He and Hill say that future research on mechanisms of abrupt climate change should take into account coastal boundary currents in redistributing ice sheet runoff and subpolar fresh water.
###
Well Ice berg drifted far longer back in 1956! Is it too much to ask to go looking in archives for things that really has happened?
And during ice age sea Level is about 120m lower than today so???
No it wasn’t that’s not so. First of all: Archimedes principle was “acting” during Ice Age as it is today.
Land was pressed down and thus the sealevel seems for unknowing people to have been h i g h e r. Actually 54 meters in areas where the ice cap wasn’t present. But you better know that you also have to take the tectonic plates into the equation.
Land that been under ice rises when ice melt. Quicker in south than land longer under ice. Thus the effect in for example Lake Vaettern, lake in middle of Sweden, is that waterlevel changed 4 meters up in northern parts of Lake Vaettern while the land that was inhabited in southern parts today is to be found more than 50 meters under.
There are 43 essential factors to take into consideration. One need to have all 43 (at least 40 of them) in any sound model. if not than it’s fiction model not at all alike reality. Empiri is one thing – so called modells an other.
Is this the same climate model the zealots use that can’t simulate its way out of a paper bag?
“Is this the same climate model the zealots use that can’t simulate its way out of a paper bag?”
No, the text makes pretty clear: “Using a first-of-its-kind, high-resolution numerical model”
It used to be, back in the beginning, that readers of WUWT had the sense to read before commenting.
The model is designed to do ocean circulation. it is 10-20 times as powerful as other models
Here is how observational science works.
1. We cannot run an experiment to see if a giant ice sheet in north america will Calve icebergs big enough
to make it to Florida.
2. We can create a physical model to examine what would happen.
The situation is exactly the same if one tries to figure out what would happen if a huge asteroid hit the earth.
We can’t go create an asteroid and have it impact the earth to test our ideas.
So you build a model. The model says that icebergs would reach Florida.
How do you confirm this model?
Hmm.. look for iceberg scour marks
http://cdn.phys.org/newman/gfx/news/hires/2014/2_seafloor_iceberg_scour.jpg
Result: model confirmed.
Steven, where are these marks? Just wondering.
Mosh says…It used to be, back in the beginning, that readers of WUWT had the sense to read before commenting.
Thanks Steve. I too am getting a bit tired of reading knee-jerk reactions to any kind of research or reports of research, posted. It seems to me that this blog is becoming more a political screed in addition to the excellent source of science news that I have come to enjoy. I do prefer the latter as opposed to the former. Perhaps a little self regulation if you please?
Steve Mosher:
“Result: model confirmed”
≤≤<<<<<>>>>><>>>>>
Model rejected
The model pute a discrete, cold water current (“several degrees above freezing”) through (per fall in sea level) a much constricted Strait of Florida, counter current to the force of the Gulf Stream. It appears that the absurdity of that has escaped you.
One does not need to postulate an absurdity to get ice bergs off the coast of Florida during the ice age.
Furthermore, theory is, or should be, formulated on observations. The scour marks are the observations, the -only- observations. And in fact they are well explained by the sightings of icebergs off Florida this century. The model is absurd and indeed symptomatic of the state of science in academia.
How do you know that the iceberg came from the North? Perhaps it followed the Gulf Stream from Antarctica. You would think Artic icebergs would end up in Europe or Western Africa due to the prevalent currents along the eastern seaboard.
Result: model not disproved.
“Mosh says…It used to be, back in the beginning, that readers of WUWT had the sense to read before commenting.
Thanks Steve. I too am getting a bit tired of reading knee-jerk reactions to any kind of research or reports of research, posted. It seems to me that this blog is becoming more a political screed in addition to the excellent source of science news that I have come to enjoy. I do prefer the latter as opposed to the former. Perhaps a little self regulation if you please?”
You can almost lay a sure bet that if the article mentions “model” tat the same folks will post the same knee jerk response. At this stage in the debate the points and counter points are all laid out.
Like a chess game only more boring
And Steve, icebergs have been reported off Florida in modern times. The scour marks prove nothing about how they were transported, and certainly do _not_ confirm a longshore cold water current originating in Hudson Bay or wherever.
“10-20 times more powerful” does not necessarily make a model 10-20 times more accurate.
From the actual article.
http://www.nature.com/ngeo/journal/vaop/ncurrent/images_article/ngeo2267-f2.jpg
These are just Gulf Stream current scours.
http://s9.postimg.org/x1fgi6x8f/Gulf_Stream_Current_Scours.jpg
You can zoom-in more from here and see lots of lines from the Gulf Stream.
https://goo.gl/maps/lTNPZ
“No, the text makes pretty clear: “Using a first-of-its-kind, high-resolution numerical mode”
Well good heavens if they say it is a first of a kind, then damn it all it must be, because it wasn’t I am sure that text would say “we used the same climate model the zealots use that can’t simulate its way out of a paper bag.” Then Oh wow, Oh wow the first of its kind, wow!!!! Only, gee, I just thought of this, even, maybe especially, first of their kind things might be wrong.
His work, conducted with Jenna Hill of Coastal Carolina University, is described in the current advance online issue of Nature Geosciences. “Determining how far south of the subpolar gyre icebergs and meltwater penetrated is vital for understanding the sensitivity of North Atlantic Deep Water formation and climate to past changes in high-latitude freshwater runoff,” the authors say.
Vital, isn’t it? For understanding the <enter something vaguely related to the most fashionable scare du jour>.
Proceed to the refectory and receive your chow.
Taxpayer shall pick up the tab.
I thought it was all models until I read further down and saw that they actually did sea bottom research and found evidence of large glaciers scouring the seabed.
Yes, this looks like real science and the correct use of models.
Models used to try and quantify understanding that can be tested against real world observations.
Hmmm. If the model runs had come first, and predicted the bergs, after which they looked and found the marks on the sea bed, I’d agree that this is valid science.
As the models came after the evidence was found, this may just be post-hoc justification.
“Hmmm. If the model runs had come first, and predicted the bergs, after which they looked and found the marks on the sea bed, I’d agree that this is valid science.
As the models came after the evidence was found, this may just be post-hoc justification.”
wrong.
you are confusing observational science with experimental science.
In observational science you start with an observation that needs explanation ( say a fossil record). Then you construct a theory to explain it. Going FORWARD, the theory makes predictions which can be tested. So, this ocean model explains the past and also predicts that if a huge ice sheet ever forms again an calves icebergs they will scour the floor. Confusing observational science with experimental science is a common mistake.
Both are ways of coming to understanding.
“As the models came after the evidence was found, this may just be post-hoc justification.”
once upon a time man observed the sun coming up. The understanding of this phenomena came after.
therefore, models of how the planets work may just be post-hoc justification.
Not glaciers – icebergs
From the Sarasota Journal – Apr 19, 1954
Ships in the Atlantic off the Florida coast were today warned to be on the lookout for – of all things – an iceberg. The SS Trinity, an American merchant ship spotted the berg 300 miles off Cape Canaveral.
Back in 2006 icebergs from Antarctica lay just off the NZ Canterbury coast (70KM) on a journey of 4000 km before heading into the wild blue yonder. A previous event was in 1931 and before that they appear in sailing ship logs back in the 1880s.
Whats also interesting is these huge bergs usually get stuck in an iceberg graveyard way South of NZ for some years and breakup. But some escape and head up the East Coast of the South Island.
http://www.niwa.co.nz/coasts-and-oceans/faq/icebergs
http://tvnz.co.nz/national-news/icebergs-north-banks-peninsula-934815
Its a remarkable reminder that Global Warming is upon us :).
JC
There was at least two very large “outbreaks” of icebergs in the Southern Ocean, in the 1860’s and 1880’s. These must have been caused by major shelf breakup events, but since nobody was around to see them they caused no media anguish.
Iceberg gouge marks are all very well to indicate that icebergs once stranded in a particular locality but they don’t tell you anything about when and how it happened. It could have been at any time during any of the many glaciations of the last 2 million years (it takes a long time for a gouge mark to disappear)
The normal (and best) way to investigate past sea-ice distribution is to study the amount and type of IRD (Ice-rafted debris) in bottom sediments. The vertical distribution will tell you when and approximately how much glacial ice reached a specific locality, and taking several cores in different places will tell you the distribution of the ice. Studying the composition of the debris will (if you are lucky) tell you approximately where the ice came from.
To validate their computer model they will need to take cores and show that:
1. IRD is present in a narrow zone off the coast of South Carolina, Georgia and Florida but not further offshore.
2. The IRD is present mostly in layers of LGM age.
3. The composition of the minerals in the IRD is compatible with an origin in the Hudson Bay and/or St Lawrence areas (it might just as well be from Baffins/Ellesmere land or Greenland)
Unfortunately there has been remarkably little study of IRD in the Western Atlantic (in contrast to the eastern side), but it is known that IRD occurs as far south as the Bermuda Rise during Heinrich Event 1 (H1), so this interval would seem to be at least as likely a candidate for iceberg-gouging as the LGM. For details see e. g.
http://www.eos.ubc.ca/~mjelline/453website/eosc453/E_prints/2003RG000128.pdf
Note also the constriction at the straight of Florida. This study assumes, evidently, that no Gulf stream passed through that during the ice age. Instead, the straight funneled a southbound cold water current. A dubious proposition but we know that it must be true because… the model says so.
The last ice age lasted one hundred thousand years, roughly. If the gouges indeed represent grounding of ice bergs (400 were reported), then that represents one grounded ice berg every 2 1/2 centuries. One grounded ice berg a century would have left a thousand gouges, approximately. One would fancy that the conditions hypothesized by the paper would have produced many more ice berg standings that the study records; several per year, in fact, or over one hundred thousand gouges. I will ever maintain that in the study of natural processes, computer models should not be substituted for neurons, assuming that those are available.
Exactly. Thankfully someone recognized that this requires further study. I read this here and from several other sources and no mention of IRD.
mpainter, it’s not hard to imagine that ocean currents were different during the last glacial period than they are today. The authors have also posited that this only took place during major melt water floods that were not annual events.
Robert W Turner
Change in the Gulf Stream? Do you posit that it did not flow through the Straits of Florida during the last glacial era? Because if it did a cold water counter current would not been possible. The study puts icebergs of 300 m depth.
The stranding of icebergs on the east coast is not implausible. The model-generated coldwater current hugging the coast is . To account for icebergs drifting against the southeast coast you need not change present circulation, as icebergs have been reported off Florida in modern times. A concentration of ice rafted debris off of the east coast only shows that ice bergs had been stranded there. It says nothing about how they got there.
Other transport mechanisms are possible. During the LGM, the North Atlantic froze over in winter, as the Arctic Ocean does now. Icebergs locked in sea ice could have been carried to the then lower shoreline by eddies of the Gulf Stream & otherwise shifting floes.
“The depth of the scours tells us that icebergs drifting to southern Florida were at least 1,000 feet, or 300 meters thick,” says Condron.
I wonder if they took into consideration the much lower sea levels during the ice age. According to NASA, global sea levels were around 120 meters lower.
I presume that they did take that into consideration. However since they have no real idea when the gouging actually happened they can’t actually know what the sea-level was at the time. By the way if they were “300 meters thick” they were rather average icebergs. Icebergs are rarely more than c. 600 meters thick because of limitations of mechanical strength of glacier ice. They can be very wide however. Iceberg several kilometers across are common in Antarctica (but not in the North Atlantic)
Iffen an iceberg had calved off of the south side of Long Island (NY), ….. and entered the water at the southeastern edge of the “Inner Shelf” (see graphic link below), ……. sometime between 12,000 and 16,000 BP, it could have, would have, been both extremely thick and/or wide.
http://www.nefsc.noaa.gov/press_release/2010/SciSpot/SS1003/HudCanFinderMap.jpg
That image just shows the ancient Hudson river outflow channel. Remember that sea level was 120 metres lower at the time and the outflow through the St Lawrence river was blocked. The main drainage from glaciers in eastern North America was through the Lake Champlain valley and down the Hudson (once the glaciers left New York and before they reached New York). And the amount of water that was melting off these glaciers in the summer would have been thousands of times higher than the current flow in the Hudson. You can see 100s of the ancient ice age river channels on the continental shelves through Google maps.
If you read the paper you would find the following:
“Both the scour morphology and correlation with stratigraphic controls on the New Jersey margin indicate that the South Carolina and Florida scours were probably formed by icebergs calving from the Laurentide Ice Sheet (LIS) following the Last Glacial Maximum (ref 8)(LGM). Relative sea level constraints at this time (70–120 m lower than modern(ref 12)) imply that iceberg keel depths ranged from 50–310 m to generate the observed scour distribution. Icebergs at this subtropical latitude would therefore have been comparable in size to those calving from the modern-day Greenland Ice Sheet margin. As iceberg melt rate is inversely related to size(ref 13), icebergs from the LIS must have been considerably larger to reach this far south without completely melting. Indeed, seafloor scours in Hudson Bay show that extremely large, tabular ‘megabergs’ (keel drafts >650 m) were sourced from the Canadian margin following the LGM (ref. 14).”
@ Bill Illis October 13, 2014 at 4:31 am
If one looks at the above graphic one can easily see the eroded channel of the Hudson River from where it exits the NYC area at the western tip of Long Island and flowed across the Inner Shelf and then down the extremely steep 120+- meters (360+ feet) face of the Outer Shelf and thus creating the Hudson Canyon.
For the outflow of the Hudson River to have caused the massive erosion resulting in the formation of the Hudson Canyon then the sea levels at the time had to have been 200 to 250 meters lower than present …. and there had to have been a large volume of fast flowing “meltwater” flowing through said Hudson River channel.
And iffen, as the experts claim, the Late Wisconsin Glacier (LWG) covered much of NYC and Long Island with ice up to or greater than 3,300 feet thick at 18,000 years BP then the southern edge of said LWG had to have extended far out overtop the Inner Shelf where the calving of said glacier would have occurred. Icebergs don’t normally calve-off over dry ground.
Who really cares?
Steven.
care is the wrong word.
who finds it interesting?
Well, as the records show, one does not need to invoke a “coastal cold water current” to get an iceberg to Florida.
There was still a Gulf-stream-like current along the US East coast at the time (unless the Earth’s rotation and winds were opposite to today as in “not”).
The icebergs would have to move against the current so a rare ice-berg calve from the New York region might have left a scar but the ice-bergs were not flowing down the US east coast from the far north.
Bill, interestingly, at this time the sand deposited in FLorida tends to drift from North to South. I understand this is caused by eddies which spin off the Gulf Stream and cause a counter current closer to shore. A similar eddy current is observed in Antarctica (I was told). I happen to know about this particular issue because I worked aboard a NOAA vessel in the 1970´s measuring the eddy shape and velocities. However, I´m not sure about eddy formation further to the North. We had a sister ship making those measurements and before I saw their results I left the program and went back to college.
Does anybody know back when the continental glaciers were melting the Gulf Stream was running offshore and spinning off eddies?
Interesting. Now confirm the hypothesis by showing us the sediment cores exhibiting abrupt, short-term(?) disturbances to the marine microfaunae that surely must accompany sudden massive influxes of fresh cold water.
BTW, where was the shoreline when these huge icebergs drifted through? Many tens of kilometers East of where it is now, right?
Where was the shoreline? Right out to the end of the continental shelves in most places.
High-res shaded relief map at the bottom of this page “3-minute arc World Map … during the peak of the last ice age” (don’t want to link to the jpg since it will show up on the page now). St Lawrence river glacial U-shaped valley is very interesting here. .
Nothing like forgetting about the link.
http://www.ngdc.noaa.gov/mgg/topo/globega2.html
Don, if they saw iceberg scour marks then that particular area must have been underwater. Evidently it must have been further offshore.
I have seen iceberg scour data offshore Russia. The scours off Sakhalin show there were icebergs sailing by, doing number eights, zig zagging, and making all sorts of moves during the ice ages. I would love to see the Eastern Seaboard scour marks to see if they are similar to what we saw.
The La Pérouse Strait between Hokkaido and Sakhalin is known to freeze solid in the winter months. According to Wiki, the passage, aka Soya Strait is between 66-160 feet deep.
Condron reports, “In order for icebergs to drift to Florida, our glacial ocean circulation model tells us that enormous volumes of meltwater, similar to a catastrophic glacial lake outburst flood, must have been discharging into the ocean from the Laurentide ice sheet, from either Hudson Bay or the Gulf of St. Lawrence.”
You know, I’m beginning to think scientists today should be taking an English BA before they are allowed into the science program. Given the language failings of junior school over the last 3 decades, science would benefit from a scientist’s ability to construct language that actually says what his science is saying.
The above direct quote is illustrative. It should say “In order for icebergs to drift to Florida, our glacial ocean circulation model requires that enormous volumes of meltwater, similar to a catastrophic glacial lake outburst flood, must discharge into the ocean from the Laurentide ice sheet, from either Hudson Bay or the Gulf of St. Lawrence.”
The model itself isn’t a statement of fact, its a presumption. In order for the model to have icebergs drift to Florida, it has to have the condition of an enormous outflow of meltwater. Its the model that’s being tested, not the iceberg drift mechanism to Florida. That remains an unknown, and yet another hypothetical based on scour marks. Disclaimer: I haven’t read the paper, and won’t, since he lost me at the above paragraph.
“You know, I’m beginning to think scientists today should be taking an English BA before they are allowed into the science program. Given the language failings of junior school over the last 3 decades, science would benefit from a scientist’s ability to construct language that actually says what his science is saying.”
junior school?
thas some good english there, bud.
“language failings?”
what the hell is that?
glass house. put down the rocks and read the paper
Mosher, why do you always feel compelled to demonstrate why you get no respect around here?
Hi Paul.
Paul Coppin October 13, 2014 at 5:31 am
Valid point. The model is a supposition. Indeed, the ‘model requires’ large quantities of melt water to account for the observations of supposed ice gouges. The model is an “if, then” statement. It does NOT confirm or provide any evidence that large quantities of melt water actually occurred at the required time and place of 21000 BCE. Thus, the model also requires the additional observations of some relevant data that support its supposition of large quantities of melt water where and when required.
We already know from recent history (and noted in several comments here), that no such large quantity of melt water is required to transport icebergs as far as Florida. Hence, the model already skates on thin ice; it posits a ‘requirement’ that is apparently not required. So it needs to make a verifiable prediction of where and of what age we will find the evidence for all that melt water.
Mosher: it would do you a lot of good to consider this comment by Michael Wassail. He states the problem succinctly.
AP,
Speaking as a single viewer, I care. This courteous professional discussion is why I frequent this site.
+1
This article is interesting, but it’s tone overall reminds me of a high school sophomore saying “Ohmygod! Did you know we had an ice age once?”
Thou doth besmircheth the gangly agog of youth frozen in time.
Uh huh. The world is a very different kind of place during times of maximum ice extent. Land is lost to the ice in some areas but gained in other areas as the oceans retreat. Once it is formed, ice is very resistant to melting, so temperatures don’t have to be all that much cooler in a lot of places to maintain the ice. Icebergs would be much more common in mid latitudes and even the subtropics and tropics. Imagine basking on a warm beach in the sun with palm trees nearby while you gaze at several large icebergs floating a mile or two out.
We live during a time in which the ice has retreated, forgetting that during most of the past few million years the oceans have been smaller and the land surfaces have supported considerably more ice than they do today. I like to think of it as a simple redistribution of H2O along who a significant alteration of weather patterns, bringing about the redistribution of deserts, forests, savannahs, and icebergs, essentially creating a different world from the one we know, not especially that much colder and neither good nor bad, just different.
21,000 years ago the Laurentide ice sheet had not yet begun to melt. Calving is also due growth of glaciers and ice sheets. So to have ice bergs drifting far south at a time of extreme cold in North America shouldn’t be considered unusual or astounding.
Blame Clovis man and their flint knapping skills. Too much CO2 released from the flint.
Yeah, you kids today with your Global Warming don’t know how easy you have it! Back in the day, when we wanted to go fishing or shrimping out there in the ocean off Florida, why, we didn’t have no fancy fish finders or radios, or even motors, we had to sail out, dodging icebergs right and left while we tried to find enough fish to feed our starving young’ens. And we didn’t have no sea level rise neither, it was a hundred mile walk to get to the ocean and launch the boat. And it was uphill both ways too!
Once again a study that purports to describe what happened.
Fine
No explanation provided at all as to WHAT CAUSED THE WARMING that allowed the ice sheets to melt. No explanation at all provided as to WHY the climate went into a warm period after a few thousand years of Cold, ice age climate conditions.
Don’t hold your CO2 laden breathes waiting for the sort of explanations that will demonstrate that climate “scientists” actually UNDERSTAND what drives climate.
Correct you are. The researchers pulled the great flood of meltwater out of thin air and offer not one shred of support for it. They do offer a computer model that turns the Gulf Stream around and makes it flow back into the Gulf of Mexico. This is done by the latest generation of super models. Mosher thinks that we are idiots for not being awed into silence.
Many of these papers seemingly have to start with (in this case) “…first-of-its-kind, high resolution numerical model…” This puts up my red flags. They always seem more interested in impressing modellers than in advancing knowledge. This reads like a bunch grads from PacMan U having to have the latest iPhone or gadget. Funding requires the use of “climate” related data to test the latest greatest computer game. How many latest greatest models can there be?
for ocean circulation? Well, the ocean models in most GCMs trace their lineage back to a couple really old models. Hmm.. I can think of a couple new high resolution ocean models. The one referenced here is 10-20x improvement ( circa 2011 when it was first reported )
They are more interested in getting published. It is very hard to publish a paper that starts with “Here we present more of the same old thing.”
So, they found the scour marks. Then they wrote the model (and fixed it repeatedly) until it had ice bergs drift to the right place.
Well gee! The observations and the model created to explain them agree! Great job kids!
This is a joke, right?
No actually the ocean model has existed for some time.
read more comment less.
Think more,do less of everything else.
I think its unfortunate that so many people, especially here at WUWT, are completely turned off by numerical modeling. Computer simulations of complicated physical situations is far more than climate models.
I agree. Some models attempting to simulate LGM conditions might be valid, since they’re checked against actual observations.
Steven Mosher
October 13, 2014 at 8:59 am
“Hmmm. If the model runs had come first,
Steve, you don’t have to try so hard to save every model. Here is what they said:
” Using a first-of-its-kind, high-resolution numerical model to describe ocean circulation during the last ice age about 21,000 year ago, oceanographer Alan Condron of the University of Massachusetts Amherst has shown that icebergs and meltwater from the North American ice sheet would have regularly reached South Carolina and even southern Florida.”
They didn’t show that ice bergs reached Florida. The glacial grooves and (they didn’t mention) rafted erratic boulders and cobbles did that. They put a model together to see if they could replicate it. It is totally wrong to say the model showed it when they already knew it in advance. I’m amazed at the grade school science project this is. Heck, even during the American Revolution the sea froze down to New Jersey – Washington’s troops moved cannons over the ice from Manhattan to NJ so that the British wouldn’t have them. They are claiming too much for their model and it still might be a fiction. Try this model:
Huge ice sheets and glaciers moving into the sea happened in the north. We have grooves and granite boulders on the sea floor. This shows that icebergs came down this far.
Moreover, comments above make mention of icebergs down there in the 1950s and in the 1800s. Moshe, it’s not science to not research all this stuff. Here is a handful of comments, data has been supplied that these guys seem oblivious of. I guess they are afraid to consult a geologist in case their “new” idea gets stolen.
” The glacial grooves and (they didn’t mention) rafted erratic boulders and cobbles did that.”
glad you were there to eyewitness that.
I’m disappointed Steven. A geologist sees a nautiloid fossil in Ordovician limestones and remarks that this shows life was present 450M years ago. It doesn’t mean the geologist is 450M years old. If eyewitnessing was essential, there wouldn’t be such a thing as a geologist or indeed many other kinds of scientists. It is ironic that the one science that tends to avoid eyewitnessing is climate science. They correct observations with their models of how things should be.
It occurred to me in responding that you thought the idea of glacial erratics as indications of glacier ice passage was fanciful. Just in case, here are some links.
http://eprints.soton.ac.uk/15067/1/15067-01.pdf
http://www.worldcat.org/title/glacial-erratics-from-the-sea-floor-south-east-of-the-faeroe-islands-and-the-limit-of-glaciation/oclc/5276107
http://academic.emporia.edu/aberjame/student/martin1/laurentide.html
Interestingly, this bit of research of 5 minutes ago (the latter link) showed that the Laurentide Ice Sheet actually extended off shore of present day Massachusetts 21,000 years ago!! This should be passed on to our electronic researchers from Amherst. The bergs probably calved in Massachusetts right under the researcher’s feet – a better bet for a Florida iceberg than Hudson’s Bay. A northerly wind would have done the job without reversal of currents.
Furthermore, theory is, or should be, formulated on observations. The scour marks are the observations, the -only- observations. And in fact they are well explained by the sightings of icebergs off Florida this century. The model is absurd and indeed symptomatic of the state of science in academia.
see the depth of the water where the scours are found and the dating of them.
Mosher:
Of course the bergs grounded during the glacial era.It seems that any and every empirical argument is lost on you
Moving forward into the Holocene, seawater temperature & salinity off Florida, in the North Atlantic & East Pacific all correlate with solar activity:
Solar forcing of Florida Straits surface salinity during the early Holocene
http://adsabs.harvard.edu/abs/2012PalOc..27.3204S
The model is not by any means completely validated by scour marks off Florida, as the icebergs could well have originated in New Jersey during Heinrich Events on both ends of the LGM (see second linked reference). While their presence in FL does imply a coastal current flowing south, it need not have originated in Canada, although that possibility can’t be ruled out. However, the coastal component of the then weaker Gulf Stream may also have offered less resistance to wind-driven icebergs (see first linked reference):
1)
Nature 402, 644-648 (9 December 1999) | doi:10.1038/45204; Received 4 May 1999; Accepted 12 October 1999
Weaker Gulf Stream in the Florida Straits during the Last Glacial Maximum
Jean Lynch-Stieglitz1, William B. Curry2 & Niall Slowey3
http://www.nature.com/nature/journal/v402/n6762/abs/402644a0.html
2)
http://geology.geoscienceworld.org/content/29/5/411.abstract
Relict iceberg keel marks on the New Jersey outer shelf, southern Hudson apron
Catherine Schuur Duncan*1 and
John A. Goff*1
+ Author Affiliations
1University of Texas Institute for Geophysics, 4412 Spicewood Springs Road, Building 600, Austin, Texas 78759-8500, USA
Abstract
Swath sonar bathymetry reveals sinuous furrows, 400 m wide, kilometers long, and 4 m deep inscribed in semilithified clays on the southern Hudson apron. We interpret these as keel marks created by floating icebergs detached from the retreating Laurentide ice sheet since ca. 25 ka. Keel-mark orientations suggest two phases of iceberg rafting. These phases could correlate with Heinrich meltwater events H2 and H1 ca. 25 and 17 ka, bracketing the late Wisconsinan glacial maximum ca. 22 ka. During Holocene transgression, some keel marks were reworked and reformed into oblique ridges where older, sandier sediments crop out at the seafloor. Relict glacial features on the New Jersey outer shelf provide a tie between the timing of Laurentide glacial retreat and the evolution of shallow stratigraphy on this mid-latitude shelf during the last global sea-level cycle (ca. 120 ka to present).
Analysis of ice-rafted debris could however locate the source of the scouring icebergs.
Today’s researchers seem to be taught to tweak models, not to analyze or collate data.
Sad but true, I haven’t read the paper, so maybe the authors do try to ID whence came the bergs which made the scour marks.
“However, the coastal component of the then weaker Gulf Stream may also have offered less resistance to wind-driven icebergs”
Icebergs are fairly immune to wind drift since they are about 90% underwater.
http://www.jstor.org/discover/10.2307/40508548?uid=3739856&uid=2129&uid=2&uid=70&uid=4&uid=3739256&sid=21104807752747
Statistical Analysis of Observed Iceberg Drift 1
ROBERT ERWIN ETTLE2
ABSTRACT. Eight iceberg trajectories observed by the US. Coast Guard during 1965, 1967, and 1968 have been subjected to preliminary analysis. The data were obtained by tracking the icebergs relative to fixed reference markers using visual bearings and radar ranges. Speed ratios and drift angles were calculated for each half hour of iceberg trajectory. It was found that at low wind speeds the effects of permanent currents, older wind-driven currents, and tidal currents predominate over wind drag and new wind-driven currents, whereas at wind speeds of over 10 knots the wind has a significant effect on the drift of an iceberg. The ratio of the drag coefficient for the iceberg’s above-water portion to the drag coefficient for its submerged portion was found to range from 1.5 to approximately 7.
http://www.britannica.com/EBchecked/topic/281212/iceberg/273738/Iceberg-distribution-and-drift-trajectories
milodonharlani October 13, 2014 at 12:05 pm
As I mentioned above in my agreement with Paul Coppin (October 13, 2014 at 5:31 am), the critical component is the large quantity of melt water required by the model to transport the ice from source to Florida. The model is an “if, then” statement: IF there is a huge quantity of melt water, THEN icebergs get to Florida.
Recent history (noted multiple times in the comments here) confirms that icebergs get to Florida without any help from large quantities of melt water. Thus the model requires supporting evidence of large quantities of melt water where and when needed to transport icebergs around 21000 BCE. Until such evidence is forthcoming, the model is just another interesting mathematical/computer diversion.
Icebergs do make it to FL now. The model also needs meltwater at 21 Ka, which is a problem. I don’t know if the authors mean radiocarbon or calendar years ago. Possibly they’re thinking of Heinrich Event 2, variously dated at 22 to 24,000 radiocarbon years ago.
By “now”, I mean later Holocene.
I guess I’d be pretty surprised had icebergs not regularly made it to Florida. In 1926 one made it to to within 150 nm of Bermuda.
Indeed, not surprising. During Heinrich Events, armadas of icebergs make it to Portugal, affecting circulation even in the Med:
http://onlinelibrary.wiley.com/doi/10.1029/2004PA001051/pdf
Thanks. Interesting paper.
The fact that dramatic changes in the Atlantic may cause dramatic changes in the Mediterranean is suggested by cores into the bottom of the Mediterranean, which show the layers changing to black ooze at times. (New vocabulary word: “Sapropels”.)
http://www.clas.ufl.edu/users/jmjaeger/gly4552/Med_sapropels_MArGeol_review.pdf
Bermuda isn’t close to Florida.
http://www.navcen.uscg.gov/?pageName=iipWhatIsTheExtremeRangeOfIcebergLocations
Some notable iceberg sightings of the past 131 years (during the Modern Warm Period):
In 1926, the southernmost known iceberg (a growler) reached 30-20 N, 62-32 W (about 150 nm from Bermuda).
In 1883, a growler was located about 200 nm south of the Azores.
In 1912, a growler was seen about 75 nm east of Chesapeake Bay, USA.
With colder water & air temperatures during the LIA, icebergs might have survived with some regularity south of 30 degrees N.
PS: No, Bermuda isn’t very close to FL, but the 1926 growler was sighted in the same latitude as Jacksonville.
To be fair, growlers aren’t really considered icebergs. It goes growlers (size of a car), bergy bits (size of a house) and then icebergs. And yeah, during the last Ice Age I’d wager icebergs got considerably south of Florida.
Growlers are considered icebergs, just little. That actually makes them dangerous, as harder to spot.
No but today the closest tidewater glaciers to Florida are in Greenland while during the LGM they were in New England.
Growlers are indeed “small icebergs” and must be distinguished from lumps of sea-ice. Growlers consist of glacial ice which is very hard and they can be quite dangerous. The “Lindblad Explorer” sank in Antarctica after hitting a growler.
tty:
The nomenclature isn’t perfect because “iceberg” means two things, ie a big iceberg, & icebergs in general, ie chunks of or melted down remains of formerly glacier or ice sheet ice, whether full icebergs, bergy bits or growlers.
Don’t know if the ice sheet edge in NY & NJ met tidewater or not at the LGM, but of course you’re right in the area of New England, where the Georges Bank was exposed, as were the Grand Banks of Newfoundland, & Flemish Cap, which was an island.
ok time for a different thought new mechanism to move icebergs to Florida couple facts to start with last glacial period depressed the crust inward to the point where Florida was twice as wide as today and not because of ocean drop but because the crust bulged up under Florida. push the crust downward and the magma pool underneath will wear the crust thin example the Hawaiian island chain formed by burning thru the crust now put that hot spot under a five to ten thousand foot ice cap on a nonmoving crust and the hot spot would melt the ice from bottom up and the center out giving us a huge fresh water ocean above sea level until the ice melt weakens the ice dam to the point wear several collapses occur at once with huge ice burgs flowing outward in all directions at which time the crust would return to its beginning state dumping the rest of the stored water back into the ocean and im willing to bet that 95% of man lived within 50 feet of ocean level just like today duh and a lot of people died in a world wide tsunami at the end of the last ice age thought if the water released slowly the huge fresh cold water release into the warm salty water would have caused huge rain storms from the energy convergence helping to weaken a collapse of the dam in several locations now please tell me why im wrong just looking for a better world lets hope for another thousand years before the next glacial period
“[…] next glacial period”
Nice to see a period at the end.
Oops. sorry, Jani. I made a flippant comment without helping you out a bit. One little fly in your hypothesis is that the rise in Florida isn’t attributed to isostatic rebound from the retreat of the glaciers, but rather that the limestone bed of Florida is getting lighter as rainwater dissolves some of the limestone. The rise is attributed to Florida floating higher on the mantle.
I’m not thrilled with the source at this link, but it plainly discusses the process as do other, less reader-friendly links.
http://news.discovery.com/earth/global-warming/florida-limestone-swiss-cheese.htm
I like the thought of rain storms hitting the ice sheet at many different places. I’ll have to cogitate on that one.
I think it makes sense that isostatic rebound in Florida might be prompted by the limestone leeching out, and becoming filled with caves. It is interesting that the dates of the three levels of elevation in Florida roughly match up with ice-ages.
However the rate of uplift in these cases seems to be very slow, on the order of 0.047 millimeters per year. The sea level rose much faster than that at the end of the ice age.
Therefore I do not think this is a case of “either-or”. It seems to be a case involving slow isostatic rebound and more rapid sea-level rises (and falls) due to ice-ages.
Keep in mind that, while the Florida Trail limestone has been uplifted 250 feet, it dates from 1.44 million years ago. During that time the oceans have gone up and down 300 feet multiple times.
(Be wary of the words “geologically recent” in such news items.)
This is a joke?
I doubt it. It is called, “Thinking outside the box”, and I enjoy it.
I have done a bit of it myself, in order to explain some of the lore involving the abrupt end of Atlantis. While it is generally assumed that isostatic rebound is a very gradual and slow process, I see no reason to never consider such uplift occurring rapidly, even as a jolt, especially when one considers the vast weight removed by “meltwater flood events.” Such jolts might cause further “catastrophic glacial lake outburst floods.”
Even if it is not science, it might be a good premise for science fiction.
Then add in a comet hitting the ice-sheet.
Double oops; Juli, not Jani. (I am blind in both eyes and my eyes do play tricks. Apologies.)
Another item, that I don’t see mentioned, is cold meltwaters coming down the Mississippi River valley into the Gulf of Mexico. The map doesn’t show any blue off the west coast of Florida. Was this even considered by the model?
Walter, that other item you don’t see mentioned; this image shows how the Appalachians would split the flow of the melt waters. It appears to me that the melt from the central portion of the ice sheet would be funneled a little further west of Florida rather than close by Florida’s west coast.
http://www.cosmographicresearch.org/Images/glacial_maximum_map2.jpg
Of course you’re right that the Gulf basin would be hit with of a lot of fresh water. I’m not clear whether or not it mattered in their model, though. Maybe the next study is to look for scour marks off the west coast ;o)
Need more grant money, eh?
(Caleb October 14, 2014 at 12:59 am)
Caleb,
Jani has Florida rising due to the weight of the glaciers mid-continent. Florida should be subsiding due to the weight being removed. It’s rising now.
If I read that one long sentence correctly, the ice bergs were sent willy-nilly across the continent in all directions as ice dams collapsed. If I recall correctly, there’s a mountain chain between the termini of the past few glaciers that would tend to block Jani’s ice bergs from floating on down to Florida. That, and I don’t recall any reports of ice berg keel marks down through Georgia. Jani’s idea just won’t float, but it was an interesting sentence.
If one looks at a graphic of the Hudson Canyon then one can easily see the eroded channel of the Hudson River from where it exits the NYC area at the western tip of Long Island and flowed across the Inner Shelf and then down the steep 120+- meters (360+ feet) face of the Outer Shelf and thus creating the Hudson Canyon.
For the outflow of the Hudson River to have caused the massive erosion resulting in the formation of the Hudson Canyon then the sea levels at the time had to have been 200 to 250 meters lower than present …. and there had to have been a large volume of fast flowing “meltwater” flowing through said channel.
And iffen, as the experts claim, the Late Wisconsin Glacier (LWG) covered much of NYC and Long Island with ice up to or greater than 3,300 feet thick at 18,000 years BP then the southern edge of said LWG had to have extended far out overtop the Inner Shelf where the calving of said glacier would have occurred. Icebergs don’t normally calve-off over dry ground.
Samuel C. Cougar:
“200 to 250 meters”
Interesting observation as that is about a hundred meters, more or less, below SL at glacial max. This implies sub-sea scour formed the lower part of the channel. How to explain this? Perhaps someone has presented a plausible explanation.
@ mpainter: October 14, 2014 at 9:34 am
“Interesting observation as that is about a hundred meters, more or less, below SL at glacial max. This implies sub-sea scour formed the lower part of the channel”.
—————-
There is a “plausible explanation” for your quandary concerning the sea level variance of 120 meters verses the 250 meters as stipulated in my above post.
The 120m figure was in reference to the vertical height of the Outer Shelf (200m – 80m = 120m), ….. and the 250m was in reference to the vertical height as measured from the very bottom of the Hudson Canyon to present day sea level at the “shoreline” of Long Island, to wit:
http://www.nefsc.noaa.gov/press_release/2010/SciSpot/SS1003/HudCanFinderMap.jpg
Thus I will assume that you confused my stated 120m cliff-height figure with the claimed 120m rise in sea levels during the Post Glacial Sea Level Rise that occurred during the pre-Holocene Period as stated on this “meltwater” proxy graph, to wit:
http://www.climate.org/images/postglacial-sea-level-rise.png
If that 120m proxy figure is correct then the actual sea level during the most recent “glacial maximum” (Ice Age) was located at 40+ meters below the top edge of the Outer Shelf. And the outflow of the Hudson River during said pre-Holocene Period would have caused additional erosion of the Hudson Canyon down to said “40 meter mark” on the Outer Shelf, …. but not below said “mark”.
But there have been several Ice Ages during earth’s history, also 1 or 2 “Snowball” earth Periods, which would explain why the erosion of the Hudson Canyon extends below the aforesaid “40 meter mark” down to 250+- meters below the current sea level.
If you use Google “Images” and search for “Hudson Canyon” it will display quite a few different graphics that will better define the erosion of the continental shelf that has occurred during the “glacial maximums” of past millenniums.
“””””…..“The depth of the scours tells us that icebergs drifting to southern Florida were at least 1,000 feet, or 300 meters thick,” says Condron. “This is enormous. Such icebergs are only found off the coast of Greenland today.”…..”””””
I somehow doubt that is true. Icebergs of that size routinely break off from Antarctica, and they can also sail all the way up to New Zealand.
Back in 2006, when I was down there touring the South Island, there was a whacking great iceberg off the coast and I could have booked a helicopter ride out to land in it.
I decided, that I wanted to remain in one piece for the time being, so I didn’t go, but lots of people did.
But those sea floor gouge marks, look rather weird. I wonder why modern ocean currents haven’t filled them in.
I also question the above quoted claim of a “1,000 feet, or 300 meters thick” iceberg simply because one can not be sure at what “time” during the pre-Holocene Post Glacial Sea Level Rise (see above graph) that said icebergs calved off of the LW glacier.
Is not said “scour” marks a function of …. iceberg mass + iceberg momentum + sea level height?