Study finds global sea levels rose up to five meters per century at the end of the last five ice age cycles

September 25, 2014
Credit: Tiago Fioreze / Wikipedia

Land-ice decay at the end of the last five ice-ages caused global sea-levels to rise at rates of up to 5.5 metres per century, according to a new study.

An international team of researchers developed a 500,000-year record of sea-level variability, to provide the first account of how quickly sea-level changed during the last five -age cycles.

The results, published in the latest issue of Nature Communications, also found that more than 100 smaller events of took place in between the five major events.

Dr Katharine Grant, from the Australian National University (ANU), Canberra, who led the study, says: "The really fast rates of sea-level rise typically seem to have happened at the end of periods with exceptionally large ice sheets, when there was two or more times more ice on the Earth than today.

"Time periods with less than twice the modern global ice volume show almost no indications of sea-level rise faster than about 2 metres per century. Those with close to the modern amount of ice on Earth, show rates of up to 1 to 1.5 metres per century."

Co-author Professor Eelco Rohling, of both the University of Southampton and ANU, explains that the study also sheds light on the timescales of change. He says: "For the first time, we have data from a sufficiently large set of events to systematically study the timescale over which ice-sheet responses developed from initial change to maximum retreat."

"This happened within 400 years for 68 per cent of all 120 cases considered, and within 1100 years for 95 per cent. In other words, once triggered, reduction (and therefore sea-level rise) kept accelerating relentlessly over periods of many centuries."

Professor Rohling speculates that there may be an important lesson for our future: "Man-made warming spans 150 years already and studies have documented clear increases in mass-loss from the Antarctic and Greenland ice sheets. Once under way, this response may be irreversible for many centuries to come."

The team reconstructed sea-levels using data from sediment cores from the Red Sea, an area that is very sensitive to sea-level changes because it's only natural connection with the open (Indian) ocean is through the very shallow (137 metre) Bab-el-Mandab Strait. These sediment samples record wind-blown dust variations, which the team linked to a well-dated climate record from Chinese stalagmites. Due to a common process, both dust and stalagmite records show a pronounced change at the end of each ice age, which allowed the team to date the sea-level record in detail.

The researchers emphasise that their values for are 500-year averages, so brief pulses of faster change cannot be excluded.

Explore further: New dating of sea-level records reveals rapid response between ice volume, polar temperature

More information: "Sea-level variability over five glacial cycles" Nature Communications, DOI: 10.1038/ncomm6076

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Returners
3 / 5 (8) Sep 25, 2014
At the present rate of average annual acceleration, the Greenland Glaciers would totally melt in about 530 years. Considering much of Antarctica would be melting as well, once things got that bad, the amount of sea level rise this represents is likely on the order of 15 meters or more.

It unlikely that human activities would continue polluting at present rates past 2100, because we're going to run out of oil/gasoline in about 3 or 4 decades anyway, but there is enough coal and natural gas to last for a few centuries, not to mention the prospect of harvesting Methane Clathrates if technology allows.

I regret that I won't be around to see our first Starship, maybe not even our first mid/outer solar system mining colony. However, if we are all lucky and our energy companies cooperate, I may see commercial/industrial fusion power technology, as well as global wind and energy technology as a major fraction of energy supplies.

orti
2.6 / 5 (10) Sep 25, 2014
Ah-ha. We're not the first to burn fossil fuels.
RWT
2.3 / 5 (6) Sep 25, 2014
That's 22 times faster than current sea level rise.
joepetjr
1.4 / 5 (11) Sep 25, 2014
More political science for dummy's.

peter_piasecki_92
2 / 5 (12) Sep 25, 2014
Sounds like the current climate is right in-line with natural variability, not man made up climate scare and fear................
guybb
1.4 / 5 (9) Sep 25, 2014
What this article fails to mention is a simple fact. That precipitous rise in sea levels they are talking about? Already happened, about 10,000 years ago. There isn't enough ice left to do more than 30 meters rise if it all melted completely and there were no ice left on earth. Which, at current rates would take at LEAST 4,000 years. So, this is just more fearmongering, chicken-little, sky-is-falling sensationalism, in a feeble attempt to divert from the real crisis, the out of control liberal spending, failed policies, and lack of leadership.
runrig
4.6 / 5 (10) Sep 25, 2014
Sounds like the current climate is right in-line with natural variability, not man made up climate scare and fear................

You do realise what you said there do you?????

You are basically saying that the Earth is now in a transition from a Milankovitch period of lower level solar energy impinging the higher latitudes of the NH to one where it is increasing .... for that is what ended the IA's, along with increased CO2 feed-back after a lag, from the oceans.
In fact it is at a low level with the SH receiving ~8% more solar energy in it's summer than the NH does in its.

Please do not comment, on this, a science site if you have nothing but ignorance to share.

FFS
runrig
4.6 / 5 (10) Sep 25, 2014
What this article fails to mention is a simple fact. That precipitous rise in sea levels they are talking about? Already happened, about 10,000 years ago. There isn't enough ice left to do more than 30 meters rise if it all melted completely and there were no ice left on earth. Which, at current rates would take at LEAST 4,000 years. So, this is just more fearmongering, chicken-little, sky-is-falling sensationalism, in a feeble attempt to divert from the real crisis, the out of control liberal spending, failed policies, and lack of leadership.

Try projecting the acceleration of rise my friend... oh and quit the political ideology, which is, of course, why you come on here with the typical stereotyped ignorant denialist whinge.
Returners
1.5 / 5 (8) Sep 25, 2014
I don't know about you guys, but I don't want the MIssissippi River to return to pre-industrial conditions and freeze solid down to Baton Rouge every year, and NOLA on cold years.

That would make our entire nation's economy completely useless for 2 or 3 months out of the year.

The worst famines in world history were actually caused by cold snaps, not heat-droughts.

I think I'll keep our Degree of "padding," thank you.
antigoracle
1.4 / 5 (11) Sep 25, 2014
I don't know about you guys, but I don't want the MIssissippi River to return to pre-industrial conditions and freeze solid down to Baton Rouge every year, and NOLA on cold years.

Not to worry, runrig has looked into his CO2 filled crystal ball and proclaimed no more ice age.
runrig
5 / 5 (7) Sep 26, 2014
I don't know about you guys, but I don't want the MIssissippi River to return to pre-industrial conditions and freeze solid down to Baton Rouge every year, and NOLA on cold years.

Not to worry, runrig has looked into his CO2 filled crystal ball and proclaimed no more ice age.


It's called science sunshine....
Quite, quite different from ideological bias.
runrig
4.4 / 5 (7) Sep 26, 2014
I don't know about you guys, but I don't want the MIssissippi River to return to pre-industrial conditions and freeze solid down to Baton Rouge every year, and NOLA on cold years.

That would make our entire nation's economy completely useless for 2 or 3 months out of the year.

The worst famines in world history were actually caused by cold snaps, not heat-droughts.

I think I'll keep our Degree of "padding," thank you.

Nothing to see here folks ....
Just the usual selfish thinking from the denier camp.
antigoracle
1 / 5 (5) Sep 27, 2014
Nothing to see here folks ....
Just the usual selfish thinking from the denier camp.

Ah, the ignoRANT of the AGW Chicken, when they choose to remain blind to the truth.
Returners
1 / 5 (5) Sep 28, 2014
Nothing to see here folks ....
Just the usual selfish thinking from the denier camp.


You haven't thought this through very well, have you?

1 Tambora, and a million people in Russia, a quarter of the globe away, starved from volcanic winter, and you had the "Year without a summer" in North America.

that's been almost exactly 200 years.

If the same eruption happened today, it would probably kill a billion people.

And there HAVE been bigger eruptions even before that:
Thera*, Taupo, Toba, and more.

When Tropical super-Volcanoes erupt they are very efficient at blocking sunlight, because the particulates are blocking the light at the highest angle, which cools equatorial waters, and the entire atmosphere. Then when the atmosphere is cooled, the heat in the temperate zone oceans gets transported back into the air, and forms snow storms which dump on the continents, wiping out crops even more than just the loss of sunlight alone would do.
runrig
5 / 5 (3) Sep 29, 2014
Nothing to see here folks ....
Just the usual selfish thinking from the denier camp.

Ah, the ignoRANT of the AGW Chicken, when they choose to remain blind to the truth.


Pot calling the kettle black.
If any rants on here it is you and ryggy.
rants don't substitute for science, and science is the truth - as well as we know it.
Now who did you say is blind?
FFS
runrig
5 / 5 (3) Sep 29, 2014
Nothing to see here folks ....
Just the usual selfish thinking from the denier camp.


You haven't thought this through very well, have you?

1 Tambora, and a million people in Russia, a quarter of the globe away, starved from volcanic winter, and you had the "Year without a summer" in North America.

that's been almost exactly 200 years.

If the same eruption happened today, it would probably kill a billion people.

And there HAVE been bigger eruptions even before that:
Thera*, Taupo, Toba, and more.


Err, Volcanoes aren't caused by AGW.
thermodynamics
5 / 5 (2) Sep 29, 2014
Run: You will probably find this to be an interesting article. Speculative, but interesting.

http://www.realcl...871.html

This is similar to the observation about the great Sumatran quake changing the length of the day.

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