Study sheds light on vulnerability of polar ice sheets to modestly warmer climate

Jul 12, 2012 by Donna Hesterman

(Phys.org) -- A new study by a University of Florida researcher finds that sea level peaked between 18 and 30 feet above current sea level during the last interglacial period approximately 125,000 years ago.

That’s significant, the researchers say, because knowing how high peaked previously tells us something about how the earth may respond as global temperatures rise again.

The finding differs from many studies on sea level during the previous warming period because the researchers use fossil coral reef data to estimate sea levels and then factor in the physics of how ever-changing ice sheets have affected those estimates. The range of sea level maximums that they estimate for the period suggests that part of the Greenland had collapsed, as well as a large portion of the West sheet and possibly sectors of the East Antarctic ice sheet.

The study appears in the July 13 edition of Science.

A sea floor is like a container for the ocean that is continually changing its shape over time, and that affects sea level. The crushing weight of the ocean alters the container by compressing the rock below it. And continents change the container as they slowly rebound from compression exerted by massive glaciers during the last ice age.

“It’s all very dynamic. Some points on the globe are rising while others are falling. And the gravitational pull of ice sheets literally causes sea level to be higher around the sheet’s perimeter. There’s also this sloshing effect caused by the confluence of these forces,” said study lead author Andrea Dutton, an assistant professor of geology at the University of Florida. “It sounds complicated, but the physics behind it is well understood.”

Kurt Lambeck, a professor of geophysics at Australian National University in Canberra, Australia used computer modeling to turn back the geological clock and recreate the expected patterns of regional sea level during the last . He and Dutton then superimposed data from fossil coral species known to live near the surface of the ocean on the model to see how high sea level rose during the period in question.

The poles were approximately 5 to 10 degrees Fahrenheit warmer than they are today.

“That’s well within range of what could occur before the end of this century,” Dutton said.

Polar temperatures are of particular concern because scientists predict that a complete collapse of an already unstable West Antarctic ice sheet could cause average sea level to rise by approximately 10 feet rather precipitously. The process may have already begun with the western shelf of Antarctica’s ice sheet slowly sloughing off into the warming waters of the Southern Ocean.

It could take more than a century for the ice sheet to melt, she said. But given the current trend of warming, the planet may already be committed to a path that the population isn’t prepared to deal with.

“This can be a runaway process,” she said.

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User comments : 12

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NotParker
2 / 5 (16) Jul 12, 2012
"The poles were approximately 5 to 10 degrees Fahrenheit warmer than they are today."

Not possible. Only humans can warm the poles. :)

"Twenty-year-old models which have suggested serious ice loss in the eastern Antarctic have been compared with reality for the first time - and found to be wrong, so much so that it now appears that no ice is being lost at all."

http://thegwpf.or...how.html
Benni
2.6 / 5 (9) Jul 12, 2012
Isn't 125,000 years ago about the time cro-magnons showed up? And then within a few thousand years the sea levels started dropping to present levels? Is it possible those Cro-magnons figured out Neanderthals were the cause of sea level rise causing global temperature rise due to their proliferation of campfires for cooking meat?

Fellow Cro-magnons, now we need to figure this out all over again & stop being "neanderthals" before the sea levels begin to rise again.
NotParker
2 / 5 (16) Jul 12, 2012
Benni, sea level was about 100 meters lower in between the Eemian and the Holocene. It has been rising for about 20,000 years.
Caliban
3 / 5 (8) Jul 13, 2012
Benni, sea level was about 100 meters lower in between the Eemian and the Holocene. It has been rising for about 20,000 years.


NutPecker.

Your comparison lacks any validity whatsoever. What matters is the cause. Cherry picking an irrelevant factoid in support of your "argument" is nothing less than deliberate lying.

But I only say this for the benefit of Benni and any others that might be misled into attaching any weight to your shilling efforts.

Howhot
2.8 / 5 (9) Jul 13, 2012
Nopark; You don't even know what Eemian and the Holocene are. Nor do you have a clue as to how modern society would even manage in the Eemian. Have you ever seen the movie "Soylent Green"? Get it.

130,000 years ago=Eemian, 12,000 years=Holocene. 2008=Eminem.

NotParker
2.5 / 5 (11) Jul 13, 2012
Nopark; You don't even know what Eemian and the Holocene are. Nor do you have a clue as to how modern society would even manage in the Eemian. Have you ever seen the movie "Soylent Green"? Get it.

130,000 years ago=Eemian, 12,000 years=Holocene. 2008=Eminem.



I know the Eemian was the last interglacial.

"began about 130000 years ago and ended about 114000 years ago"

It was a lot warmer, hippos roamed in the UK.

Sea level was a lot higher.

"Sea level at peak was probably 4 to 6m (13 to 20 feet) higher than today (references in Overpeck et al., 2006), with much of this extra water coming from Greenland"
NotParker
2.5 / 5 (11) Jul 13, 2012
Benni, sea level was about 100 meters lower in between the Eemian and the Holocene. It has been rising for about 20,000 years.


NutPecker.


Spectators probably want to be careful about paying attention to the rabid name callers. They are not very rational.
Estevan57
1.7 / 5 (22) Jul 14, 2012
NotParker, having you call someone else not rational is pretty damn funny, given the record of your posts.
jyro
2.5 / 5 (8) Jul 14, 2012
The Earth has been getting warmer and colder for 4 billion years. The only constant in Earths environment is change. It will continue to change till its consumed by the Sun.

Caliban
3.5 / 5 (4) Jul 15, 2012
Benni, sea level was about 100 meters lower in between the Eemian and the Holocene. It has been rising for about 20,000 years.


NutPecker.


Spectators probably want to be careful about paying attention to the rabid name callers. They are not very rational.


Nutpecker,

They would also be well advised to ignore the endless spew of claptrap and falsehood purveyed here by shills such as your own pathological self.

If you want respect, then stop insulting everyone's intelligence with these deliberate lies.
Shootist
1.5 / 5 (8) Jul 15, 2012
NutPecker

Your comparison lacks any validity whatsoever. What matters is the cause. Cherry picking an irrelevant factoid in support of your "argument" is nothing less than deliberate lying.

But I only say this for the benefit of Benni and any others that might be misled into attaching any weight to your shilling efforts.


No buttwheat, you're wrong.

The climate has been both warmer and colder than today, and that within the last 1000 years, and the last 2000 years (it was colder than today 1600 years ago and 650 years ago. All of those temperatures are normal. Today is normal. Yesterday is normal and tomorrow will be as well.

When there are 400 year old vineyards in Scotland (vineyards existed in Scotland during Roman times (AD 20) and during Viking times (AD 900-1250), call, 400 year old vineyards require warm temperatures, for 400 years. Temperatures that are much warmer than any seen today.

So, look into the historic record, it provides guidance to what is normal.
Caliban
5 / 5 (3) Jul 17, 2012

No buttwheat, you're wrong.

The climate has been both warmer and colder than today, and that within the last 1000 years, and the last 2000 years (it was colder than today 1600 years ago and 650 years ago. All of those temperatures are normal. Today is normal. Yesterday is normal and tomorrow will be as well.

When there are 400 year old vineyards in Scotland (vineyards existed in Scotland during Roman times (AD 20) and during Viking times (AD 900-1250), call, 400 year old vineyards require warm temperatures, for 400 years. Temperatures that are much warmer than any seen today.

So, look into the historic record, it provides guidance to what is normal.


And there are grapevines in freaking Maine, too. So what? you are well aware that the Gulf Stream has a climate moderating influence over the UK and western Europe.

You are also aware that your Greenland Dairy Farm hypothesis is just that.

Find some compelling evidence to cite or continue to be ignored.

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