Ocean model error shows climate change may be worse than expected

New research shows that ancient oceans may not have been as warm as models show.
By Ian Marsh | Oct 31, 2017
Models used to estimate past ocean temperature may be flawed, which could call into question many current perceptions of climate change.

This new discovery comes from a team of European researchers, who found that our ancient seas may have been much cooler than previously estimated. That in turn means Earth's current warming trends are much more powerful than scientists believe.

While researchers cannot definitively know the state of ancient oceans, they estimate them on the belief that their temperatures were preserved inside tiny marine organisms known as foraminifera.By looking at the ancient creatures, scientists determined that the deeper parts of the tropical oceans some 100 million years ago were about 60 degrees Fahrenheit warmer than they are today.

However, that may not be true.

"What appeared to be perfectly preserved fossils are in fact not," said lead author Sylvain Bernard,a mineralogist from the French National Center for Scientific Research, in a statement.

The team found this discrepancy by analyzinghow the chemistry of the calcite in the foraminifera's shells could change over time. They did that by putting some of the organisms inartificial sea water that contained just isotopes of oxygen-18.Then, they raised the temperature and used a nanoscale secondary ion mass spectrometer to analyze changes in the calcite's oxygen ratios.

That revealed the ratios did shift over time. As a result, any evidence based on the organisms may be incorrect.In fact, the new data shows that ancient waters were not much warmer than they are today.

The new findings suggest Earth's oceans are getting hotter at a faster rate than previously thought.Now that they know this, the team plans to go back to square one and take a look at existing data. They hope that will help them figure out what difference the changes make to historical records and give them a better idea of what shifts may occur in the future.

"To revisit the ocean's paleotemperatures now, we need to carefully quantify this re-equilibration, which has been overlooked for too long," said study co-author Anders Meibom, a geochemist from the Swiss Federal Institute of Technology in Lausanne, according toScience Alert."For that, we have to work on other types of marine organisms so that we clearly understand what took place in the sediment over geological time."

The new findings are detailed in the journal Nature Communications.

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