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An Oceanographer Explains Why We Should Explore Earth’s Complex Climate History

Ayusmati S. Manaskanya, an oceanographer at the National Institute of Oceanography in Goa, believes than an understanding of the Earth’s climate history can help make better statistical models to predict future climate.

Ayusmati S. Manaskanya. Credit: The Life of Science

Ayusmati S. Manaskanya. Credit: The Life of Science

Under the Bay of Bengal, a three-meter deep layer of the planet’s surface lay undisturbed for the past 10,000 years until the crew aboard the scientific vessel Marion Dufresne extracted it. The French ship boasts of a state-of-the-art ‘corer’ named Calypso that dug into this seabed at the Krishna-Godavari basin off the shores of Andhra Pradesh.

Since the day she met her sample, Manaskanya has been studying it thoroughly. First, she geologically dated it to confirm that the sediment was formed 10,000 years ago. She then made subsamples and began a multitude of experiments to test the biological, geological and chemical, together called the biogeochemical composition of the core.

Its atoms and molecules tell the story of the past, making the core an archive that equips Manaskanya to estimate the paleoclimate – Earth’s climate when this sediment formed thousands of years ago.

Guessing the paleoclimate to model future climate

“Actually the most common way oceanographers study the Paleoclimate is with fossils of ancient organisms foraminifera,” Manaskanya said as we started the interview about her research. The sulphur and calcium carbonate from the fossils are inorganic ‘proxies’ for past climate. But Manaskanya uses another strategy; her focus is on the core’s organic geochemistry.

Each of the organic elements (which are what the bodies of lifeforms are predominantly made of) like carbon, oxygen and nitrogen are preserved under water in different forms or isotopes, which vary in the number of protons and neutrons in their atoms. For example, some of the oxygen atoms are heavy and some are light. By comparing the ratio of heavy and light isotopes in the core to a geological standard, Manaskanya can get clues about the past climate.

“These isotopes not only answer questions about the paleoclimate, but also fill the gaps in our understanding of the nitrogen cycle, carbon cycle and the overall biogeochemistry involved in the ocean,” she said.

Another ‘proxy’ that Manaskanya studies, is the indicative marine plants that compose her sample. Studying the carbon isotopes in the core can tell which kinds of plants lived at that time. This is a major clue to the monsoon patterns that existed at the time when very few humans roamed the planet.

Besides earning Manaskanya her Ph.D. degree, these proxies will serve as the missing piece of an important puzzle. “Until now, it has not been possible to accurately model future climate patterns because of the complex and restless nature of our planet’s climate. Knowing the major events in the Earth’s climate history will enable us to make better predictions and prepare, say when a cyclone is going hit our nation.”

Manaskanya shows her ability to look at the big picture, as all Council of Scientific & Industrial Research (CSIR) scientists are expected to while explaining the applicability of her research. “With our analysis, we can report important weather events that have happened in the past. With this information, my colleagues in the physical oceanography department – the mathematicians – can make better and better statistical models to predict future climate.”

“For example, we can observe events like the El Nino, which occurs every two-seven years. In this way, the frequency of a weather event can be predicted. We can say that this kind of event will repeat in this particular year or predict that monsoon will be heavy in this year or warn the country of a cyclone that could impact its economy with so much severity. Such predictions can enable preparation that can save lives and secure the future of the country.”

Being discovered as a scientist