MAR 30, 2016 7:30 AM PDT

Climate shifts linked to ocean chemistry

U. TORONTO (CAN) — Humans often take the blame for climate change, but new research examines another force at work: the chemistry of the world’s oceans.
 
Are oceans to blame for climate shifts?

Scientists from the University of Toronto and the University of California, Santa Cruz point to changes in seawater chemistry as one potential cause of the cooling trend of the past 45 million years.

“Seawater chemistry is characterized by long phases of stability, which are interrupted by short intervals of rapid change,” says Ulrich Wortmann, a professor in the earth sciences department at the University of Toronto and lead author of the study published in Science.

“We’ve established a new framework that helps us better interpret evolutionary trends and climate change over long periods of time,” says Wortmann. “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 the dissolution or creation of such massive gypsum 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 gypsum—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.”

More news from the University of Toronto: https://news.utoronto.ca/

This article was originally published on futurity.org.
About the Author
  • Futurity features the latest discoveries by scientists at top research universities in the US, UK, Canada, Europe, Asia, and Australia. The nonprofit site, which launched in 2009, is supported solely by its university partners (listed below) in an effort to share research news directly with the public.
You May Also Like
AUG 17, 2020
Earth & The Environment
When do cold-climate forests turn from carbon sinks to carbon sources?
AUG 17, 2020
When do cold-climate forests turn from carbon sinks to carbon sources?
A study led by University of Michigan researchers and published recently in PNAS reports that cold-climate forests ...
AUG 27, 2020
Plants & Animals
Polar Bear Populations Could Collapse by 2100
AUG 27, 2020
Polar Bear Populations Could Collapse by 2100
A new study reports that polar bear populations could collapse in the next 80 years if greenhouse gas emissions remain a ...
SEP 10, 2020
Plants & Animals
Saving Myanmar's Critically Endangered Turtles
SEP 10, 2020
Saving Myanmar's Critically Endangered Turtles
New images of hatchling Burmese roofed turtles have renewed hope to save this critically endangered species. Late last m ...
OCT 14, 2020
Earth & The Environment
That's not really how atolls form...
OCT 14, 2020
That's not really how atolls form...
A study published this month in the Annual Review of Marine Science challenges the accuracy of Darwin’s theor ...
OCT 26, 2020
Earth & The Environment
Is more iron a good thing for the oceans even if it comes from coal power plants?
OCT 26, 2020
Is more iron a good thing for the oceans even if it comes from coal power plants?
A team of researchers from USC, Columbia University, University of Washington, MIT and the University of Hawaii, have fo ...
NOV 30, 2020
Earth & The Environment
How is the Mongolian Plateau faring climate change?
NOV 30, 2020
How is the Mongolian Plateau faring climate change?
New research published in the journal Science predicts the future of Mongolia’s semi-arid plateau, saying tha ...
Loading Comments...