One key interval of particular interest during the Pliocene is the mid-Piacenzian Warm Period – some 3.264 to 3.025 million years ago – when temperatures were 2 to 3º Celsius higher than pre-industrial levels. “The interval also marks the last time the Earth’s atmospheric CO2 was as high as today, providing important clues about what the future holds in the face of current anthropogenic warming,” Onac says.
This study found that during this period, global mean sea level was as high as 16.2 meters (with an uncertainty range of 5.6 to 19.2 meters) above present. This means that even if atmospheric CO2 stabilizes around current levels, the global mean sea level would still likely rise at least that high, if not higher, the scientists concluded. In fact, it is likely to rise higher because of the increase in the volume of the oceans due to rising temperature.
Mallorcan cave yields 4-million-year-old geologic evidence providing new insights into magnitude global sea level rise
An international team of scientists, studying evidence preserved in speleothems in a coastal cave, illustrate that more than three million years ago – a time in which the Earth was two to three degrees Celsius warmer than the pre-industrial era – sea level was as much as 16 meters higher than the present day. Their findings represent significant implications for understanding and predicting the pace of current-day sea level rise amid a warming climate.
The scientists, including Professor Yemane Asmerom and Sr. Research Scientist Victor Polyak from The University of New Mexico, the University of South Florida, Universitat de les Illes Balears and Columbia University, published their findings, Constraints on global mean sea level during Pliocene warmth, in today’s edition of the journal Nature. The analysis of deposits from Artà Cave on the island of Mallorca in the western Mediterranean Sea produced sea levels that serve as a target for future studies of ice sheet stability, ice sheet model calibrations and projections of future sea-level rise, the scientists said.
Sea level rises as a result of melting ice sheets, such as those that cover Greenland and Antarctica. However, how much and how fast sea level will rise during warming is a question scientists have worked to answer. Reconstructing ice sheet and sea-level changes during past periods when climate was naturally warmer than today, provides an Earth’s scale laboratory experiment to study this question according to USF Ph.D. student Oana Dumitru, the lead author, who did much of her dating work at UNM under the guidance of Asmerom and Polyak.