Ancient Sea Levels Uncovered By Scientists Are Revealing Clues To The Ice Ages And Future Climate Change

Climate-related sediment cycles at Punta Maiata, Sicily. Photo: Eelco Rohling

A team of international researchers led by the Australian National University have developed a new way to determine sea-level changes and deep-sea temperature over the past 5.3 million years.

The findings will help scientists better understand the climate surrounding ice ages over the past two million years and help determine the relationship between carbon dioxide levels, global temperatures and sea levels.

The team from the ANU, the University of Southampton and the National Oceanography Centre in the UK examined oxygen isotope levels in fossils of microscopic plankton recovered from the Mediterranean Sea dating back as far as 5.3 million years.

“This is the first step for reconstructions from the Mediterranean records,” says lead researcher Eelco Rohling from the ANU Research School of Earth Sciences.

The team focused on the flow of water through Strait of Gibraltar which was particularly sensitive to sea-level changes.

“As continental ice sheets grew during the ice ages, flow through the Strait of Gibraltar was reduced, causing measurable changes in oxygen isotope ratios in Mediterranean waters, which became preserved in the shells of the ancient plankton,” he said.

The findings are published in the latest on-line edition of Nature.

The findings will help scientists better understand the nature of ice ages and development of coastal sediment.

A more refined sea-level record over millions of years also allows a better understanding of coastal sediment sequences that are relevant to the petroleum industry.

And the work will allow detailed comparisons between past atmospheric carbon dioxide concentrations, global temperatures, and sea levels, which has enormous value to long-term future climate projections.

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