Scientists say ocean fossils found in mountains are cause for concern over future sea levels

September 22, 2016 by Tom Parisi, Northern Illinois University
A 3 million-year-old Pliocene diatom fossil (Thalassiosira vulnifica), about 1/25th of a millimeter across, magnified more than 1,000 times, as seen in an optical microscope. Credit: Reed Scherer, Northern Illinois University

Tiny ocean fossils distributed widely across rock surfaces in the Transantarctic Mountains point to the potential for a substantial rise in global sea levels under conditions of continued global warming, according to a new study.

The study, led by Northern Illinois University geologist Reed Scherer, indicates the massive East Antarctic Ice Sheet (EAIS) has a history of instability during ancient and could be vulnerable to significant retreat and partial collapse induced by future climate change. The EAIS is the world's largest and most significant player in potential .

The evidence is in the microscopic ocean fossils, known as diatoms, the researchers say.

For decades, scientists have been embroiled in a heated debate over how the diatoms, which were first discovered in the 1980s, became incorporated into the "Sirius Group," a series of glacial sedimentary rocks exposed along the Transantarctic Mountains.

One group of scientists argued that the diatoms accumulated in a marine basin after ice sheet retreat and later, after it got much colder, were moved by the growing glaciers to the mountains. This interpretation suggested a dramatic retreat of the ice sheet between 3 million and 4.5 million years ago, during warm periods of the Pliocene Epoch. But other scientists contended the ice sheet remained stable for at least the past 5 million years, arguing that the diatoms were carried by the wind and deposited atop older sediments.

Credit: Northern Illinois University

The new study, published Sept. 20, in Nature Communications, suggests that both sides were partially right and partially wrong—the ice sheet did retreat, and the wind did carry the diatoms.

Using sophisticated ice sheet and climate models, Scherer and colleagues found the ice sheet experienced a series of retreats and re-advances during the Pliocene warm periods, but the retreats were not as dramatic as some scientists earlier suggested. They were significant enough to uncover bays of open seawater in the Aurora and Wilkes basins, with conditions ripe for production of copious amounts of plankton diatoms.

But the retreat removed the weight of the ice, allowing previously submerged land strewn with diatoms to rise above sea level over the next few thousand years. Cyclonic winds then sent plumes of diatoms airborne, depositing them across the Transantarctic Mountains.

"The computer models indicate that the East Antarctic Ice Sheet retreated during the Pliocene by some 300 miles into the interior of East Antarctica," Scherer said, adding that most of the West Antarctic Ice Sheet also disappeared. "So our findings indicate the Sirius diatoms were windblown, but they came from areas of reduced ice in East Antarctica, where extensive -rich lands became exposed to the air."

The Antarctic ice cap holds the majority of the world's fresh water, and a substantial melting and retreat of the ice sheet in the future would result in raised sea levels, with devastating consequences for the world's coastal regions.

Sirius Group exposures near Mt. Fleming, Antarctica, circa 1986. The pattern of snow behind rocks shows the prevailing winds across the East Antarctic Ice Sheet. Credit: Reed Scherer, Northern Illinois University

"During certain intervals of Pliocene warmth, the sea level could have been as much as 75 feet higher than it is now," Scherer said.

"The rise in atmospheric carbon dioxide from burning fossil fuel has now elevated the concentration to 400 parts per million, matching for the first time the levels of the warm Pliocene," he added. "This makes the old debate about whether the ice sheet was notably smaller than it is now more relevant than ever."

Models used for the research were developed by co-authors David Pollard of Pennsylvania State University and Robert M. DeConto of the University of Massachusetts.

"The question is always how quickly could sea levels rise, and we're probably looking at several hundred years into the future before reaching a peak high that matches the Pliocene, but the problem of progressive sea-level rise is already upon us," Scherer said. "The DeConto/Pollard models assume we continue to burn fossil fuels at the current pace. If we make improvements for the better, ice sheet reduction could be significantly delayed. We'd still have a problem, but we could keep the sea-level rise small and slow."

The new research represents the first published study on the Sirius fossils that presents data directly related to or indicative of East Antarctic Ice Sheet thickness during the Pliocene.

An electron-microscope image of diatom-rich sediment magnified more than 3,000 times, illustrating fine structures that promote being lifted and carried as dust in the wind. Credit: Reed Scherer, Northern Illinois University

"This latest work, together with other recent ice sheet modeling studies by DeConto and Pollard, clearly demonstrates the sensitivity of modern ice sheets to warming," Scherer said. "No model is ever perfect, but these scientists use sophisticated physics and the latest data to produce atmospheric and ice models that are truly state-of-the-art, providing a picture of the past and glimpse into our future."

Noted climate scientist Richard Alley, also of Penn State, rounds out the author list on the Nature Communications publication.

"This is another piece of a jigsaw puzzle that the community is rapidly putting together, and which appears to show that the ice sheets are more sensitive to warming than we had hoped," Alley said. "If humans continue to warm the climate, we are likely to commit to large and perhaps rapid sea-level rise that could be very costly. No one piece of the puzzle shows this, but as they fit together, the picture is becoming clearer."

Explore further: Sea-level rise could nearly double over earlier estimates in next 100 years

More information: Reed P. Scherer et al. Windblown Pliocene diatoms and East Antarctic Ice Sheet retreat, Nature Communications (2016). DOI: 10.1038/ncomms12957

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plaasjaapie
1.4 / 5 (11) Sep 22, 2016
"The rise in atmospheric carbon dioxide from burning fossil fuel has now elevated the concentration to 400 parts per million, matching for the first time the levels of the warm Pliocene," he added. "This makes the old debate about whether the ice sheet was notably smaller than it is now more relevant than ever."

So, was there another highly industrialized civilization on Earth then to cause such a high CO2 level in the atmosphere? :-/
Moebius
3.9 / 5 (7) Sep 22, 2016
The good news is that the deniers will be around to see how stupid they are. They should all be forced to buy shoreline real estate.
BrettC
2.3 / 5 (3) Sep 22, 2016
Yes but, due to volcanic or earthquake activity, land masses can exhibit vertical movement.
gregthepeg
1.8 / 5 (5) Sep 22, 2016
Like Al Gore and Tim Flannery have Moebius?
leetennant
3.9 / 5 (7) Sep 22, 2016
"The rise in atmospheric carbon dioxide from burning fossil fuel has now elevated the concentration to 400 parts per million, matching for the first time the levels of the warm Pliocene," he added. "This makes the old debate about whether the ice sheet was notably smaller than it is now more relevant than ever."

So, was there another highly industrialized civilization on Earth then to cause such a high CO2 level in the atmosphere? :-/


These people apparently can tie shoes and work computers. I find it endlessly outstanding. If only they'd spent as much time reading as they do typing we wouldn't have this stupid geological time argument on. every. damn. article.
leetennant
4.6 / 5 (9) Sep 22, 2016
I imagine someone going to their doctor and having this conversation

"If you don't stop smoking, you're going to get cancer."
"No I won't.
"Yes you will. Studies have shown that cigarette smoking causes lung cancer."
"No they don't."
"Yes they do. Here's the literature."
"That was manufactured by the anti-smoking lobby for money."
"Why would getting people to STOP buying something make more money than getting them to KEEP buying it?"
"Well, they have to have a reason to lie. It must be money."
"But we just established the people motivated to lie are cigarette manufacturers."
"No they're not. Besides, I read online people got lung cancer before the invention of cigarettes."
"Well, yes, but their lung cancer was caused by something else."
"But you said smoking was the only cause of cancer."
"No, I said smoking was a cause of cancer."
"Shifting goalposts are you? How convenient."

10yrs later
"You have lung cancer."
"Oh, how can anyone have foreseen this act of God?!"
guptm
2 / 5 (8) Sep 22, 2016
Do not threaten those who do not know or know less. There is nothing to worry. Human-induced climate change is not new. It started when humans came into existence.

Should humans stop living? Human-induced climate change is 100% natural phenomenon. Do you know that the earth has almost been devoid of any type of life twice in its geological history?

If life survived Pliocene, it will thrive again after it's lost. Life on earth is outside human-control.
leetennant
3.9 / 5 (7) Sep 22, 2016
You state that human-induced climate change started when humans came into existence but is also a 100% natural phenomenon? And you managed to do it *in the same sentence*.

Then you claim that countering climate change is wrong because humans shouldn't stop living but at the same time contend that human extinction is no big deal.

Even for a denier, you are really really confused

Bongstar420
3.7 / 5 (3) Sep 25, 2016
This would be soo bad ass. I don't see why people can't enjoy warming the place up

Or would you rather have a mile of ice over New York? I can go with that, but we gotta agree on which direction would be preferable. We most certainly won't get our current climate. Just look at how long they lasted for the last...about 1/10th of the time its like it is now. We go warmer, maybe it will stay warmer.
leetennant
5 / 5 (3) Sep 26, 2016
To anyone with an open mind, please read over this article:
https://answersin...eatures/

Don't come back with personal attacks. Just read the article, and respond from a scientific viewpoint.



Hahahahahahaha.

*insert scientific analysis of the social purpose of laughing your ass off*
antialias_physorg
5 / 5 (3) Sep 26, 2016
. If only they'd spent as much time reading as they do typing we wouldn't have this stupid geological time argument on.

Reading ain't the problem. Education/understanding is. They come from a point where "what feels right at first glance therefore must be right". i think Steven Colbert coined a good term for this "truthiness".

(In essence they are the proverbial "fools soon parted from their money", as they believe anything too good to be true. In their case it isn't their money they are parted from but the full time of their lives.)
OdinsAcolyte
1 / 5 (3) Sep 26, 2016
whatever.

It's cold.
leetennant
5 / 5 (2) Sep 27, 2016
Ah, the old "But I'm cold today" argument. Still so compelling.
Captain Stumpy
not rated yet Sep 27, 2016
Don't come back with personal attacks. Just read the article, and respond from a scientific viewpoint
@barfV
1- you don't accept science, you argue against it with religion

2- there is absolutely no science in your article

3- where was the water before the great flood? and where did it go after the flood?
magic? did it freeze and relocate to f*cking Pluto/Charon?
what?
where?

4- you have YET to answer (using science) the request i made specifically to you about refuting the following arguments with references: http://www.talkor...comdesc/

so, until you actually abide by your own post and actually answer *my request* with valid science then all you really deserve is ridicule for being a fanatical fundamentalist who is attempting to undermine reality and kill off the future with blatant stupidity

you are no different than ISIS/ISIL
antialias_physorg
5 / 5 (1) Sep 27, 2016
where was the water before the great flood? and where did it go after the flood?

What's bugging me more than the water is: Why was god so angry with all the land animals that he had to kill them off except for the two survivors. What did they do to deserve this?
And if there is a reason: Why was he so pleased with all the fish that he didn't do the same to them?

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