From the University of Chicago and the “I didn’t know Jaws lived near the North Pole ” department:
Shark teeth analysis provides detailed new look at Arctic climate change
A new study shows that some shark species may be able to cope with the falling salinity of Arctic waters that may come with rising temperatures.
The Arctic today is best known for its tundra and polar bear population, but it wasn’t always like that. Roughly 53 to 38 million years ago during what is known as the Eocene epoch, the Arctic was more similar to a huge temperate forest with brackish water, home to a variety of animal life, including ancestors of tapirs, hippo-like creatures, crocodiles and giant tortoises. Much of what is known about the region during this period comes from well-documented terrestrial deposits. Marine records have been harder to come by.
A new study of shark teeth taken from a coastal Arctic Ocean site has expanded the understanding of Eocene marine life. Leading the study was Sora Kim, the T.C. Chamberlin Postdoctoral Fellow in Geophysical Sciences at the University of Chicago, in coordination with Jaelyn Eberle at the University of Colorado, Boulder, and their three co-authors. Their findings were published online June 30 by the journal Geology.
The Arctic is of special interest today because it is increasing in temperature at twice the global rate. According to Kim, past climate change in the Arctic can serve as a proxy to better understand our current climate change and aid future predictions. The Eocene epoch, she said, is like a “deep-time analogue for what’s going to happen if we don’t curb CO2 emissions today, and potentially what a runaway greenhouse effect looks like.”
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  IMAGE: Sora Kim has analyzed oxygen 18 and oxygen 16—two isotopes of the oxygen atom that contain only slight subatomic variations — of fossil and modern sharks teeth for insights into…
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Before this study, marine records primarily came from deep-sea cores pulled from a central Arctic Ocean site, the Lomonosov Ridge. Kim and Eberle studied shark teeth from a new coastal site on Banks Island. This allowed them to better understand the changes in ocean water salinity across a broader geographic area during a time of elevated global temperatures. Shark teeth are one of the few available vertebrate marine fossils for this time period. They preserve well and are incredibly abundant.
To arrive at their results, Kim isolated and measured the mass ratio of oxygen isotopes 18 to 16 found in the prepared enameloid (somewhat different from human tooth enamel) of the shark teeth. Sharks constantly exchange water with their environment, so the isotopic oxygen ratio found in the teeth is directly regulated by water temperature and salinity. With assumptions made about temperatures, the group was able to focus on extrapolating salinity levels of the water.
The results were surprising. “The numbers I got back were really weird,” Kim said. “They looked like fresh water.” The sand tiger sharks she was studying are part of a group called lamniform sharks, which prefer to stay in areas of high salinity.
“As more freshwater flows into the Arctic Ocean due to global warming, I think we are going to see it become more brackish,” said Eberle, associate professor of geological sciences at CU-Boulder. “Maybe the fossil record can shed some light on how the groups of sharks that are with us today may fare in a warming world.”
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 IMAGE: Both graceful and docile, this modern sandtiger shark swims through a school of round scad fish in the coastal waters off North Carolina. Modern sand tigers prefer waters of high…
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Because the teeth are 40 to 50 million years old, many tests were run to eliminate any possible contaminates, but the results were still the same. These findings suggest that sharks may be able to cope with rises in temperature and the subsequent decrease of water salinity. It has long been known that sharks are hardy creatures. They have fossil records dating back some 400 million years, surviving multiple mass extinctions, and have shown great ecological plasticity thus far.
Additionally, these results provide supporting evidence for the idea that the Arctic Ocean was most likely isolated from global waters.
“Through an analysis of fossil sand tiger shark teeth from the western Arctic Ocean, this study offers new evidence for a less salty Arctic Ocean during an ancient ‘greenhouse period,'” said Yusheng (Chris) Liu, program director in the National Science Foundation (NSF)’s Division of Earth Sciences, which co-funded the research with NSF’s Division of Polar Programs. “The results also confirm that the Arctic Ocean was isolated during that long-ago time.”
While Kim has hopes to expand her research both geographically and in geologic time in an effort to better understand the ecology and evolution of sharks, she remarked that “working with fossils is tricky because you have to work within the localities that are preserved. “You can’t always design the perfect experiment.”
Col Mosby says:
July 9, 2014 at 9:20 am
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Any creatures that can trace its ancestory back millions of years have experienced significant change.
Don’t forget that the Holocene Optimun was just 8,000 years ago, and the Arctic may have been ice free or substtantially ice free then. All Arctic species that are still here today, survived that event, so why won’t they cope should there be a return to temperartures last seen during the Holocene Optimum? No one is yet forecasting temperatures greater than that, so nothing to reseach or worry about.
As regards migratory species, heck they migrate.
The Arctic is of special interest today because it is increasing in temperature at twice the global rate.
My math is weak, what is 2 X nothing?
James Strom says:
July 9, 2014 at 11:12 am
Eric says:
July 9, 2014 at 10:02 am
If I remember correctly, “brackish” refers to the slightly salty water of estuaries and bayous, as opposed to sea water.
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In shipping that is definitely the case.
It is relevant for assessments of draft, and sometimes vessle stability.
Specific gravity is commonly cited:
Water, pure 39.2degF (4degC) 1.000
Water, sea 77degF 1.025
It is temperature dependent.
There is no standard for brackish water, Theoretically, it being above 1.000 and below 1.025, but it is commonly regarded to be more in the region 1.006 to 1.015.
All ports (and significant waterways) will provide details of the specific gravity, and there can be seasonal variations. When precise figures are required (which can be the case when a ship is near to its limits) samples are taken for measurment.
There are reference/conversion tables such as those found at http://www.greatlakes-seaway.com/en/pdf/NOAA_conversion_table_tm-139%5B1%5D.pdf
So if one is suggesting that there is a tendancy for sea water to become brackish, one is suggesting that the saltiness is decreasing, and thereby the specific gravity is decreasing.
The reverse is so, if fresh water is becoming brackiish then its saltiness is increasing so too, its specific gravity.
If you want funding to study Eocene shark teeth, you have to hang your grant application on global warming from CO2, obviously.
Some think the Azolla Event, a plant bloom in the Arctic Ocean, drew down the high CO2 levels of that epoch. Carbon dioxide concentration crashed catastrophically from around 3500 ppm in the early Eocene (c. 56 Ma) to 650 ppm during this alleged event (c. 49 Ma), which may have lasted about 800,000 years. Estimates of course vary.
As noted above, the Arctic was even more landlocked in the Eocene than now.
http://en.wikipedia.org/wiki/Azolla_event#mediaviewer/File:Early_Eocene_Arctic_basin.PNG
Do not eat the meat of this Arctic shark:
http://en.wikipedia.org/wiki/Greenland_shark
There was a runaway greenhouse effect during the Eocene?
Kim’s argument seems to be that a warmer world means a less saline Arctic Ocean, and woe to the poor sand sharks, but their own research confirms “…that the Arctic Ocean was isolated during that long-ago time.” The simplest explanation would appear to be that isolation is what caused the decrease in salinity. Even today, the Arctic is the most brackish of the world’s seas.
And if the Arctic Ocean was surrounded by temperate forests during the Eocene, how exactly would warmer conditions cause the Arctic Ocean to become more brackish during that epoch?
Col Mosby says:
If anyone really wants to know whether certain species will survive global warming, rather than make gross estimates and guesses, why not just observe which species weathered warm periods in the past? Seems a much more accurate and straightforward approach to me.
Since alarmists believe that current warming is somehow unlike past warming they wouldn’t think of doing that.
Whereas if you think that nothing unusual is happening such a thing is obvious.
Steve P says:
July 9, 2014 at 11:44 am
Some regard the proposed Paleocene-Eocene Thermal Maximum (PETM) as a GHG runaway, but the homeostatic earth quickly reined it in.
Duster says:
Since the global rate at present is zero, twice that is not too worrisome.
LOL!
..Azolla event…isolated Arctic……..stratified fresh water
Yep. may^2 means “not going to happen”.
Am I the only person who read the first line of the article and wondered what Jews living near the north pole has to do with sharks?
Anyone who has ever spent anty time in the Arctic in summer knows that top of the Food Chain is held by the mosquito. The Arctic Mosquito.
We had one land at the airport one day and we pumped 50 gallons of Jet A into that sucker before we realized it wasn’t a 747. And that was a juvenile.
Polar bears. . . pfffft. They fear the Arctic Mosquito.
Fred form Canuckistan says:
July 9, 2014 at 12:17 pm
Are there daily limits on the take? Assume season is open as long as they hatch.
I was confused by two contradictory statements in this piece. The first is a subheading near the beginning, and the second is in the body of the article, near the end. Notice the contradiction?
“A new study shows that some shark species may be able to cope with the rising salinity of Arctic waters that may come with rising temperatures.”
“These findings suggest that sharks may be able to cope with rises in temperature and the subsequent decrease of water salinity.”
Which is it, “rising salinity” or the “decrease of water salinity”? I think the error is in the subtitle, which doesn’t come from the original article. The original only talks about decreasing salinity. The opening paragraph in the original says this:
“…some shark species could handle the falling Arctic salinity that may come with rising temperatures.”
The subtitle here changed “falling Arctic salinity” to “rising salinity.” This mistake should be corrected to prevent confusion.
“””””…..The Arctic is of special interest today because it is increasing in temperature at twice the global rate……”””””
“””””….. Leading the study was Sora Kim, the T.C. Chamberlin Postdoctoral Fellow in Geophysical Sciences at the University of Chicago,…..”””””
So Mrs / Ms / Miss Kim, prior to your “study”, were you aware that the Arctic (also the Antarctic )
ARE SUPPOSED TO warm / cool at much higher than the global rate; so that is not any anomaly.
The secret to this is in Thermodynamics; not Sharks.
I don’t suppose your Doctoral (of what) thesis was in thermodynamics, was it ??
The total range of Temperatures (near surface / not near volcanoes) on earth, is over 150 deg.C; about 180 K to about 330 K, and a very large fraction of that range can exist simultaneously on any northern mid Summer day.
So the total surface emittance is likely to be about 11.3 :1 ratio from hotspots to cold spots. The ratio of peak spectral emittance is even higher; around 20.7 times.
And those coldest spots should emit, right at the peak of the CO2 15 micron LWIR band, while at the hottest spots, the peak wavelength is further into the atmospheric window, and is even below the Ozone absorption band.
So hey Sora; the hottest places on earth cool way faster than the coldest spots, so naturally, the arctic should warm faster than the global mean rate.
Also, both the atmospheric, and the oceanic currents pipe a whole lot of tropical “heat energy” to the polar regions, which aids in cooling the tropics, and gives the polar regions more work to do, in cooling, which they do a totally lousy job of.
So nothing new here Sora; we already knew the poles warm faster. And don’t forget it takes a whole lot more heat energy to raise the temperature of a hot spot (by say 1 deg. C) than it takes to do the same at a cold spot.
So take a course in thermodynamics Dr.Kim, and it will all make sense.
I see you’re a post doc fellow, at an institution. That’s the career terminus for 65% of USA Physics PhD graduates, who evidently did their theses, on something, nobody is interested in paying for.
But sharks, aren’t really Physics, so perhaps you did something else.
So maybe those sharks have learned to adapt, in the last 50 million years or so. They can be found way up in some fresh water rivers, in Australia, and other places.
Now as for rising temperatures, and rising salinity. It seems to me that when the arctic ocean waters freeze (every year they do that), the segregation coefficient for salt, favors the liquid phase (water) over the solid phase (ice), and vast amounts of salt are expelled into the still liquid arctic waters, so increased melting of Arctic sea ice , and also land run-off, would be expected to lower the salinity, of the Arctic ocean; not raise it.
“The Arctic is of special interest today because it is increasing in temperature at twice the global rate.”
Twice nothing is still nothing.
“so the isotopic oxygen ratio found in the teeth is directly regulated by water temperature and salinity. With assumptions made about temperatures, the group was able to focus on extrapolating salinity levels of the water.”
If the salinity results make no sense, perhaps it’s because your assumptions about temperatures are off?
milodonharlani says:
July 9, 2014 at 12:24 pm
Fred form Canuckistan says:
July 9, 2014 at 12:17 pm
Are there daily limits on the take? Assume season is open as long as they hatch.
Not really, but they seemed to be satisfied with one or two adults, but if there were only teenagers around they might drag off 3 or 4 of them.
Fred form Canuckistan says:
July 9, 2014 at 12:52 pm
I’ll be sure to put on weight before heading north again. And load double 0 buck.
Sherman will be so pleased “http://shermanslagoon.com/”
🙂
“The Arctic is of special interest today because it is increasing in temperature at twice the global rate.”
—
Wait a minute. Didn’t Cowtan and Way confirm just last November that “the Arctic is warming at about eight times the pace of the rest of the planet”? Has their research been retracted? Or did even other climate scientists have trouble swallowing their peer-reviewed nonsense?
Of course, since the rest of the planet isn’t warming and hasn’t during the entire lifetime of my 8 grandchildren, they could both claim to be right. (2 x 0) = (8 x 0) = (1,000,000 x 0) = 0. So they could say the Arctic is warming at a rate that is almost infinitely faster than the rest of the planet and still have zero warming taking place there. But that would mean they were deliberately being deceptive. Truth seeking scientists wouldn’t stoop to that level, would they?
“As more freshwater flows into the Arctic Ocean due to global warming, I think we are going to see it become more brackish,” said Eberle, associate professor of geological sciences at CU-Boulder.
WTF? Fresh water making the ocean more brackish? And this guy is a perfesser?
“Climate change” is a tautology (google is your friend). Climate is always changing. “Climate” means climate change. To talk about climate change is to advertise the fact that your IQ is about the same as your shoe size.