Ice Sheets Can Retreat 'In a Geologic Instant,' Study of Prehistoric Glacier Shows

Jun 21, 2009
Jason Briner's research reveals that modern glaciers in deep ocean water can undergo periods of rapid retreat, where they can shrink even more quickly than has recently been observed.

(PhysOrg.com) -- Modern glaciers, such as those making up the Greenland and Antarctic ice sheets, are capable of undergoing periods of rapid shrinkage or retreat, according to new findings by paleoclimatologists at the University at Buffalo.

The paper, published on June 21 in Nature Geoscience, describes fieldwork demonstrating that a prehistoric glacier in the Canadian Arctic rapidly retreated in just a few hundred years.

The proof of such rapid retreat of ice sheets provides one of the few explicit confirmations that this phenomenon occurs.

Should the same conditions recur today, which the UB scientists say is very possible, they would result in sharply rising , which would threaten coastal populations.

"A lot of glaciers in Antarctica and Greenland are characteristic of the one we studied in the Canadian Arctic," said Jason Briner, Ph.D., assistant professor of geology in the UB College of Arts and Sciences and lead author on the paper. "Based on our findings, they, too, could retreat in a geologic instant."

The new findings will allow scientists to more accurately predict how global warming will affect ice sheets and the potential for in the future, by developing more robust climate and ice sheet models.

Briner said the findings are especially relevant to the Jakobshavn Isbrae, Greenland's largest and fastest moving tidewater glacier, which is retreating under conditions similar to those he studied in the Canadian Arctic.

Acting like glacial conveyor belts, tidewater glaciers are the primary mechanism for draining ice sheet interiors by delivering icebergs to the ocean.

"These 'iceberg factories' exhibit rapid fluctuations in speed and position, but predicting how quickly they will retreat as a result of is very challenging," said Briner.

That uncertainty prompted the UB team to study the rates of retreat of a prehistoric tidewater glacier, of similar size and geometry to contemporary ones, as way to get a longer-term view of how fast these glaciers can literally disappear.

The researchers used a special dating tool at UB to study rock samples they extracted from a large fjord that drained the ice sheet that covered the North American Arctic during the past Ice Age.

The samples provided the researchers with climate data over a period from 20,000 years ago to about 5,000 years ago, a period when significant warming occurred.

"Even though the retreat was ongoing throughout that whole period, the lion's share of the retreat occurred in a geologic instant -- probably within as little as a few hundred years," said Briner.

The UB research reveals that the period of rapid retreat was triggered once the glacier entered deep ocean waters, nearly a kilometer deep, Briner said.

"The deeper water makes the glacier more buoyant," he explained.

"Because the rates of retreat were so much higher in the deep fjord, versus earlier when it terminated in more shallow waters or on land, the findings suggest that contemporary tidewater glaciers in Greenland and Antarctica that are retreating into deep waters may begin to experience even faster rates of retreat than are currently being observed," said Briner.

Right now, Jakobshavn Isbrae is draining into waters that are nearly a kilometer deep, he said, which means that its current rates of retreat -- as fast as 10 kilometers in the past decade -- could continue for the next hundred years.

"If modern glaciers do this for several decades, this would rapidly raise global sea level, intercepting coastal populations and requiring vast re-engineering of levees and other mitigation systems," said Briner.

Source: University at Buffalo (news : web)

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Shootist
3 / 5 (14) Jun 21, 2009
""If modern glaciers do this for several decades, this would rapidly raise global sea level, intercepting coastal populations and requiring vast re-engineering of levees and other mitigation systems," said Briner."

Have they not feet? Can they not walk? Especially if the "geologic instant" in several hundred years?

As Dyson pointed out in the NYT interview, disruption is not necessarily bad.

Another point you climate nihilists always fail to point out; in human history, warm climates are far better than cold, and second, you have not defined what the planet's ideal climate is.

Would you prefer the climate of the 1790's? When the Hudson froze solid enough for canon to cross at Haarlem Heights? Or would you prefer the climate of the 950's A.D. when there were dairy farms in Greenland? Or, perhaps the climate of the 1250's when Iceland was cut off by sea ice for years at a time?

Which one is it?
Azpod
3.4 / 5 (13) Jun 21, 2009
I really wonder when scientists will finally acknowledge that the cooling trend exists and that the climate follows a cyclical, not an geometric, curve.

NOTHING in nature follows a truly geometric curve. _NOTHING!_

Sure, populations of bacteria may appear to follow a geometric curve when there is nothing to hinder their growth, but nature doesn't work that way. Even in a petri dish with a growth medium, the growth curve turns out to be asymptotic over time, not geometric.

But the lovely thing about cyclical curves and asymptotic curves are: they both appear geometric when one looks at a short segment of the curve.

That's why the Population Bomb theory was so popular in the 1970s & 1980s: because the population growth curve looked like it was geometric. We now know, based on the slowing rate of population growth, that the true curve is asymptotic. No one's predicting 30-50 billion people on Earth by 2050 anymore. The better prediction based on a real understanding of the curve is that the population will level off at between 12-15 billion people at around 2060 and will remain in that range for the foreseeable future.

So you think we'd learn that lesson about global climate change. Yes, the Earth was warming (it's now starting the cooling cycle.) Yes, there's a man-made component. Will it result in catastrophe? Hardly. The Earth will cool, then warm, then cool as it has for eons.
fhtmguy
3.2 / 5 (13) Jun 21, 2009
The only people that will try to keep the current "gobal warming" scenario alive are those who benefit either by money or power. How much scientific proof will it take to convince people of the natural eb & flow of the gobal climate. Records indicate that the temps have fluctuated for millions of years based on sun cycles, volcanic eruptions, ocean currents, natural types of gas emissions and many other occurances that are beyond the control of mere humans. Of course "Super Humans" are now developing a plan to slow or reverse GW. They have even convinced farmers that altering the diet of cows can reduce methane emissions.(see this link - http://news.yahoo...ess_cows ) These super humans have somehow managed to infiltrated the government undetected! They will continue to wreek havoc on the pocketbooks of every American, stealthily removing cash from the wallets of innocent victims and redistributing that cash to the poor nations who will, in the the future, affect GW the most. Wake up America before its too late!
disputed
2.7 / 5 (9) Jun 21, 2009
according to a book "Unstoppable Global Warming: the 1500 year cycle" by S. Fred Singer and Dennis Avery, we are not in a cooling cycle. The cooling cycle went from about 1300 to 1850 and now we're in a warming cycle. The 1500 yr cycle has mostly a solar origin and GW is not made man at all. One cycle is a cold warm period. The following is from the book cited above:

(1350yr)
cold period 0750BC - 0200BC
warm period 0200BC - 0600AD Roman Period

(850yr)
cold period 0440AD - 0900AD Dark Ages
warm period 0900AD - 1300AD Medieval Period

(1200 yr)
cold period 1300AD - 1850AD Little Ice Age Part 1&2
warm period 1850AD - 2500AD current warming period

There are fluctuations in the length of the "1500" yr cycles since solar cycles are averages of actual cycles and actual cycles themselves vary in length

Given the above, I would like to hear Azpod's evidence for the claim we're in a cooling cycle.
Shootist
2.3 / 5 (6) Jun 22, 2009
according to a book "Unstoppable Global Warming: the 1500 year cycle" by S. Fred Singer and Dennis Avery, we are not in a cooling cycle. The cooling cycle went from about 1300 to 1850 and now we're in a warming cycle. The 1500 yr cycle has mostly a solar origin and GW is not made man at all. One cycle is a cold warm period. The following is from the book cited above:



(1350yr)

cold period 0750BC - 0200BC

warm period 0200BC - 0600AD Roman Period



(850yr)

cold period 0440AD - 0900AD Dark Ages

warm period 0900AD - 1300AD Medieval Period



(1200 yr)

cold period 1300AD - 1850AD Little Ice Age Part 1&2

warm period 1850AD - 2500AD current warming period



There are fluctuations in the length of the "1500" yr cycles since solar cycles are averages of actual cycles and actual cycles themselves vary in length



Given the above, I would like to hear Azpod's evidence for the claim we're in a cooling cycle.



I take no issue with the information you provided. At least the dates are correct.

However, I must note that the typical inter-glacial lasts about 10000 years. We are currently at 12000 years and counting.
RAL
2.1 / 5 (7) Jun 22, 2009
Interesting that all the discussion in the article involves the potential speedup of glacier retreat. Is this a one way path? Wouldn't it also be true that a slowed retreat into more shallow water would cause a marked deceleration of retreat? Why then does nobody even mention this?

At least Briner says that such predictions are "challenging". I anticipate that this observation will be overlooked as the AGW models begin churning out worst case predictions designed to coincide primarily with Congressional hearings.
jonnyboy
2.1 / 5 (11) Jun 22, 2009
One must wonder how it is that these massive glaciers could vanish in such a short period of time without the assistance of CO2 being released into the atmosphere by mankind?

H M M M M M M M M M M M ?????????????
HeyZeuss
2.2 / 5 (10) Jun 22, 2009
"Have they not feet? Can they not walk? Especially if the "geologic instant" in several hundred years?

As Dyson pointed out in the NYT interview, disruption is not necessarily bad.

Another point you climate nihilists always fail to point out; in human history, warm climates are far better than cold, and second, you have not defined what the planet's ideal climate is."

Fantasys are so attractive for those like you it seems!

When over 10x current rainfall, and constant violent tropical storms make the land inhabited by 90% of humans today a very difficult place for survival, and the desert belts expand towards the poles, leaving agreeable temperate climate as a few slivers of landarea near the arctic circle, and only agreeable in summer? Maybe then you will stop playing the fool and defending the glutonous greed without empathy for the children of humans, and the mostly extinct now and the rest on the brink other species of this planet. Thats what is happening. Thats what over 2000x the rate of warming and co2 increase we have voided from our bowels has done. The runaway feedbacks triggered that will multiply our appalling massacre of our earthly flatmates so far by at least 10x the current devastation of climate and ecosystem are darn near past mitigation efforts at this point.
Rick69
3.7 / 5 (6) Jun 22, 2009
Just look at HeyZeuss's logic, he says we will have ten times the current rainfall yet in the same sentence says that desert belts will expand towards the poles. I would like to see his map of how and where thses seemingly mutually exclusive events are going to occur.
Azpod
3.7 / 5 (6) Jun 22, 2009
Given the above, I would like to hear Azpod's evidence for the claim we're in a cooling cycle.
There are several overlapping cycles at work here. I've yet to hear about the 1500 year cycle, but the one I'm talking about is the Pacific Decadal Oscillation:
http://en.wikiped...illation

Satellite data shows that the rate of global warming slowed and has even started to reverse in the last decade, in line with what is expected with the PDO model but _not_ what was predicted with global warming models.

Glacial melt is a trailing indicator of warming, which is why you're seeing so many stories about it by the GW alarmists.
Shootist
2.3 / 5 (6) Jun 22, 2009
Fantasys are so attractive for those like you it seems!

When over 10x current rainfall, and constant violent tropical storms make the land inhabited by 90% of humans today a very difficult place for survival, and the desert belts expand towards the poles, leaving agreeable temperate climate as a few slivers of landarea near the arctic circle, and only agreeable in summer? Maybe then you will stop playing the fool and defending the glutonous greed without empathy for the children of humans, and the mostly extinct now and the rest on the brink other species of this planet. Thats what is happening. Thats what over 2000x the rate of warming and co2 increase we have voided from our bowels has done. The runaway feedbacks triggered that will multiply our appalling massacre of our earthly flatmates so far by at least 10x the current devastation of climate and ecosystem are darn near past mitigation efforts at this point.


At least my original comment was based in fact. Warm climates have always been better for mankind than cold.

You didn't touch the "optimal climate" question either. EPIC FAIL.
Parsec
3.5 / 5 (8) Jun 22, 2009
It never ceases to amaze me that people continue to claim that global warming is some kind of manufactured political invention with a goal towards a few people making a lot of money, acquiring power, etc. In fact the ONLY controversy right now is inside political circles and on the periphery of science noobs who think they know a crap load more science than they do.

Science has a large variety of wonderfully correcting mechanisms to eliminate this sort of fraud. Yet, the gentleman above would claim that 90% of the scientists in the world are either in cahoots in a global conspiracy, or know less than they do about the mechanisms and details of how climate changes. Its kind of like walking up to a nuclear reactor and convincing the operators that the way they are exchanging the fuel is wrong based on a quick read of a high school textbook.

As far as the comment about warmer climates being 'better', its really not about what is better or worse from a pure climate perspective. Human cities are located based on current coastlines, human populations are clustered in those places with rainfall, and the same goes with lots of other species. If the climate gets a lot warmer humankind and other species will require a massive adjustment, simply because the global givens we have based our civilization on will change. Its very difficult, and expensive to move a city or a few million people because their homes will be underwater.
jyro
2.6 / 5 (5) Jun 22, 2009
90% of 3146 surveyed agree with global warming. Over 10,000 were sent the survey. 3146 replyed.
That's not, "90% of the scientist in the world".
http://www.eureka...1609.php
CWFlink
3 / 5 (2) Jun 24, 2009
"The UB research reveals that the period of rapid retreat was triggered once the glacier entered deep ocean waters, nearly a kilometer deep, Briner said."

And so how does the retreat of a FLOATING glacier cause the rise of ocean levels?

A ton of floating ice displaces the same volume of water after it melts. This is basic science.

The article claims that glaciers melt more rapidly once they enter deep water, and then seems to extrapolate back to suggest that the rapid melting progresses back into the area where the ice sheet is resting on land. What possible reason exists for this?

The ocean only rises when ice supported by land masses (!!!) melts and flows into the sea.

I think the rising sea level claim is either a misunderstanding by the news reporter or an attempt by the author to gather attention by playing on one of the popular misconceptions promoted by AGW advocates.
GrayMouser
1 / 5 (1) Jun 26, 2009
It never ceases to amaze me that people continue to claim that global warming is some kind of manufactured political invention with a goal towards a few people making a lot of money, acquiring power, etc. In fact the ONLY controversy right now is inside political circles and on the periphery of science noobs who think they know a crap load more science than they do.



Science has a large variety of wonderfully correcting mechanisms to eliminate this sort of fraud. Yet, the gentleman above would claim that 90% of the scientists in the world are either in cahoots in a global conspiracy, or know less than they do about the mechanisms and details of how climate changes. Its kind of like walking up to a nuclear reactor and convincing the operators that the way they are exchanging the fuel is wrong based on a quick read of a high school textbook.

When it is allowed to function, science will, eventually correct itself. What is going on now is not science, it is political advocacy. The "90%" number is an appeal to authority which is, in and of itself, proof of nothing.
Flakk
3 / 5 (2) Jun 27, 2009
One must wonder how it is that these massive glaciers could vanish in such a short period of time without the assistance of CO2 being released into the atmosphere by mankind?


They hide that information in books.
austux
1 / 5 (1) Jun 28, 2009
I see very little information pointing to more than _one_ Ice Age, am wondering if that Ice Age was much later than we assume?

I say "assume" because I have seen zero evidence which is stronger than inferential for actual dates, & if archaeologists can have serious arguments about dates only a little over 2000 years ago for events & associations we have artefacts for, where does that leave a planetologist?
austux
5 / 5 (1) Jun 28, 2009
They hide that information in books.
Ah! So the burning of the books releases the required Co2? (-:
GrayMouser
1 / 5 (1) Jul 02, 2009
I see very little information pointing to more than _one_ Ice Age, am wondering if that Ice Age was much later than we assume?

I say "assume" because I have seen zero evidence which is stronger than inferential for actual dates, & if archaeologists can have serious arguments about dates only a little over 2000 years ago for events & associations we have artefacts for, where does that leave a planetologist?

Your not supposed to ask those questions.
Nor should you wonder the use of historical values, determined through proxies, with (supposedly) precise modern direct measurements to make a continuous plot with extremely high precision.
lengould100
1 / 5 (1) Sep 01, 2009
When it is allowed to function, science will, eventually correct itself. What is going on now is not science, it is political advocacy. The "90%" number is an appeal to authority which is, in and of itself, proof of nothing.
My question is, why should anyone believe (you) that science is not functioning now? The only significant attempts at science which oppose the IPCC conclusons are "think tanks" funded primarily by fossil fuel interests. Why do few if any of them publish their work in respected peer-reviewed scientific literature?

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