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Scientists Connect Seawater Chemistry With Climate Change And Evolution; Gypsum Eyed As Ancient Climate Influencer
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TORONTO, Canada -- Humans get most of the blame for climate change, with little attention paid to the contribution of other natural forces. Now, scientists from the University of Toronto and the University of California Santa Cruz are shedding light on one potential cause of the cooling trend of the past 45 million years that has everything to do with the chemistry of the world's oceans.

"Seawater chemistry is characterized by long phases of stability, which are interrupted by short intervals of rapid change," says Professor Ulrich Wortmann in the Department of Earth Sciences at the University of Toronto, lead author of a study to be published in Science this week. "We've established a new framework that helps us better interpret evolutionary trends and climate change over long periods of time. The study focuses on the past 130 million years, but similar interactions have likely occurred through the past 500 million years."

Wortmann and co-author Adina Paytan of the Institute of Marine Sciences at the University of California Santa Cruz point to the collision between India and Eurasia approximately 50 million years ago as one example of an interval of rapid change. This collision enhanced dissolution of the most extensive belt of water-soluble gypsum on Earth, stretching from Oman to Pakistan, and well into Western India – remnants of which are well exposed in the Zagros mountains.

The authors suggest that the dissolution or creation of such massive gyspum deposits will change the sulfate content of the ocean, and that this will affect the amount of sulfate aerosols in the atmosphere and thus climate. "We propose that times of high sulfate concentrations in ocean water correlate with global cooling, just as times of low concentration correspond with greenhouse periods," says Paytan.

"When India and Eurasia collided, it caused dissolution of ancient salt deposits which resulted in drastic changes in seawater chemistry," Paytan continues. "This may have led to the demise of the Eocene epoch – the warmest period of the modern-day Cenozoic era – and the transition from a greenhouse to icehouse climate, culminating in the beginning of the rapid expansion of the Antarctic ice sheet."

The researchers combined data of past seawater sulfur composition, assembled by Paytan in 2004, with Wortmann's recent discovery of the strong link between marine sulfate concentrations and carbon and phosphorus cycling. They were able to explain the seawater sulfate isotope record as a result of massive changes to the accumulation and weathering of gyspum – the mineral form of hydrated calcium sulfate.

"While it has been known for a long time that gyspum deposits can be formed and destroyed rapidly, the effect of these processes on seawater chemistry has been overlooked," says Wortmann. "The idea represents a paradigm shift in our understanding of how ocean chemistry changes over time and how these changes are linked to climate."


The findings are reported in the paper "Rapid Variability of Seawater Chemistry over the Past 130 Million Years." The research is supported by a Discovery Grant to Wortmann from the Natural Sciences and Engineering Research Council of Canada, and a National Science Foundation CAREER award to Paytan. Data used in the research was collected through the Integrated Ocean Drilling Program (IODP) and facilitated by the United States Implementing Organization (USIO) and the Canadian Consortium for Ocean Drilling (CCOD).

Views expressed in this article do not necessarily reflect those of, its staff or its advertisers.

Reader Comments

4 people have commented so far. cloud add your comment

Excellent sourse material, wonderfull findings. I am glad science continues looking for answers to the global changes that happen,and have happened, insted of jumping on any "popular" bandwagon of thought in these reguards.
   comment# 1   - allen4acn@yahoo · Sweet Home, Oregon (USA) · Jul 21, 2012 @ 11:04am

The key attribute is humanities massive aquatic thermal contribution has accumulated and turned into a worldwide low level thermal aquatic presence, which has altered the thermal balance of nature (conduction value) within the planets colder regions. The reason for the thermal build-up, is the oceans predominant inwards direction of conduction, which causes the waters to hold onto and store this additional thermal energy, creating the thermal build-up. It is feared that the extraction of oil from under the oceans, might also be adding to aquatic warming, by increasing the normal rate in which thermal energy is normally being transferred from the hotter planet surface into the colder waters. This reality has been supported by preliminary lab experiments. No government agency has yet to require the oil industry to insure that this isn't happening. The biggest concern of there being an aquatic thermal build-up, naturally is the rapid decline in the planetary ice, which is triggered by the neutralization of the conduction value within the colder regions, where it is most fragile and susceptible to such a thermal accumulation.
   comment# 2   - Randall Scott · La Center, WA · Jul 23, 2012 @ 1:55pm

I have sailed on the oceans a great deal, and can assure you that warming the waters that surround this earth have to be seen as deep, not just broad, and that depth plus the overall size of the bodies of water would take a tremendous amount of heat, plus a long, long time to change overall temperature enough to affect the earth's climate enough to make a difference. As noted above, too many TV watching, non-readers accept as fact the suggestion that efforts to work with the earth's materials causes this HUGE earth to cool or heat... arrogance, pure arrogance. Plants mutate, animals come and go as species, man changes, mountains erode, and we cool and heat, ice and melt... Wake up... That is the planet earth's way of doing business. We are guests, the Earth IS, and will always be in our lifetime, for sure. They run the show their way. How we behave can hardly affect this ball, no matter what.
   comment# 3   - Master Chief Radarman E. Emahiser · Powell TX, usa · Jul 26, 2012 @ 7:31pm

"That is the planet earth's way of doing business. We are guests, the Earth IS, and will always be in our lifetime, for sure. They run the show their way." congecture. monologuing is always dangerous chief.
   comment# 4   - Mea · USA · Aug 28, 2012 @ 10:59am
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