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.”
sand tigers can be found in rivers, bays, etc….anything from low salinity to fresh water
these people are idiots
“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.”
Holy lord liftin’ dyin’ crap. A double-may. This basically says absolutely NOTHING.
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.
“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.”
Surprisingly there was no industry and no cars in the Eocene. What caused the C02 emissions then? Also if the Eocene was a runaway greenhouse effect, who stopped it?
Modern-era shark species occupy every ocean on the planet from the equator to the arctic, enduring a wide range of temperature, pressure and saline differences. They are probably THE world’s best adaptable survivors – why is this only now a surprise?
No cars in the Eocene? What about the Eocene Edsel?
“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.”
Funny, they always seem to imply that it’s a hellscape, but from what I understand, during the Eocene there was a lush green rainforest from pole to pole. Seems like a paradise to me. I wonder why the ecoloons are not pushing for more CO2 then.
“The Arctic is of special interest today because it is increasing in temperature at twice the global rate”
Is there a list anywhere where all the areas that are warming at twice the global rate are listed?
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.”
That’s the next grant funding secured, then! As Mike Bromley says, this is nonsense (crap imho).
When there was 7000ppm CO2 in the atmosphere there was no “runaway global warming”, so what pray tell does she think is going to cause it now after 500 million years? How on Earth is 400 or even 600 ppm CO2 going to cause it? Sheesh!
“The Arctic is of special interest today because it is increasing in temperature at twice the global rate. ”
Or perhaps it’s 1000 times the global rate. This is divide-by-zero territory.
Neil says:
July 9, 2014 at 9:50 am
“The Arctic is of special interest today because it is increasing in temperature at twice the global rate”
Is there a list anywhere where all the areas that are warming at twice the global rate are listed?
Since the global rate at present is zero, twice that is not too worrisome.
Sorry but WTF?
“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.”
““As more freshwater flows into the Arctic Ocean due to global warming, I think we are going to see it become more brackish,”
The tagline doesn’t match up with the information in the article. The Arctic Ocean would become less saline with more freshwater added…
I have the same question as Eric. How does more freshwater due to global warming cause the Arctic waters to become more saline? How does that work? Is it along the same lines as global warming causing more extreme winters?
Quit reading as soon as I saw “may” twice in the first two sentences.
Latitude
sand tigers can be found in rivers, bays, etc….anything from low salinity to fresh water
Hard to be sure. But apparently there are two externally somewhat similar sharks identified popularly as “sandtigers”. Judging from the text and the teeth pictured, the Arctic teeth they were working with are from the genus Odontaspis — which is a common fossil at US East Coast Eocene sites. Modern Odontaspis is said to prefer fairly high salinity. The other “sandtiger” is a Carcharinid. Some species of Carcharinid are quite tolerant of low salinity. If memory serves, the freshwater sharks of Lake Nicaragua are carcharinids (albeit a different species)
So maybe there is a naming confusion here.
For more data than almost anyone wants on Odontaspis, see http://webcache.googleusercontent.com/search?hl=en&q=cache:_xLYvrKq_ZcJ:http://www.redmic.es/bibliografia/Docum_01985.pdf%2Bodontaspis+salinity&gbv=1&as_q&spell=1&&ct=clnk
caveat. I did not read, and do not intend to read every word of the document I cited. Neither am I an expert on sharks. But I have some familiarity with fossil shark teeth and I’m pretty sure that the teeth pictured are from Odontapsis sp.
But can the delicate Arctic environment handle the inevitable Sharknados?
“The results were surprising. ‘The numbers I got back were really weird,’ Kim said.”
I was taught that when the result is ‘weird’ you need to go back and question your assumptions.
I think when you are dealing with a species whose modern forms go back about 100 million years, it’s a safe assumption they can cope with “climate change”.
Louis says:
July 9, 2014 at 10:16 am
“I have the same question as Eric. How does more freshwater due to global warming cause the Arctic waters to become more saline?How does that work? Is it along the same lines as global warming causing more extreme winters?”
___________________
It really isn’t all that complicated and 97% of climate scientists understand the process. Warmer air holds more moisture, so it is probable that more snowfall might occur in the Arctic, causing the ice to be insulated from the extra- warm Arctic air, increasing possibilities that even more ice may form, expelling salt and causing brackish Arctic water. The extra- salty water could interfere with and might change responses within the Arctic food chain and thus, models suggest that vast ecological disruption could occur on a scale unimagined before and which requires more study.
And who or what paid for this study, and why?
Don K says:
July 9, 2014 at 10:30 am
caveat. I did not read, and do not intend to read every word of the document I cited. Neither am I an expert on sharks. But I
have some familiarity with fossil shark teeth and I’m pretty sure that the teeth pictured are from Odontapsis sp.did stay at a Holiday Inn Express.There, FIFY 🙂
For anyone who is curious about how isolated the Arctic was in Eocene times, there are paleomaps readily available on the Internet. Here’s a link to a Middle/Upper Eocene reconstruction. Other time periods can be accessed from links at the site. http://www.scotese.com/lateeoc1.htm
Did someone say shark?
http://www.comingsoon.net/news/tvnews.php?id=116569
Sharknado 2… coming soon to a TV near you.
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.
more soylent green! said:
July 9, 2014 at 10:36 am
But can the delicate Arctic environment handle the inevitable Sharknados?
————
Even worse: shark polar vortices!