Melting ice caps have raised sea levels up to 18 meters

It is well known that climate-induced sea level rise is a major threat. New research has revealed that previous ice loss events could have caused sea level to rise at rates of around 3.6 meters per century, offering vital clues as to what lies ahead if climate change sets in. continued relentlessly.

A team of scientists, led by researchers at Durham University, used geological records of past sea levels to shed light on the ice caps responsible for a rapid boost in sea level rise in Earth’s recent past.

Geological records tell us that at the end of the last Ice Age, around 14,600 years ago, sea level rose ten times the current rate due to Meltwater Pulse 1A (MWP-1A); a 500-year sea level rise event, ~ 18 meters.

So far, the scientific community has not been able to agree on which ice sheet is responsible for this rapid rise, with the enormous Antarctic ice sheet likely being suspect, but some evidence points to ice caps in the hemisphere. North.

The new study uses detailed geological sea level data and advanced modeling techniques to reveal the sources of MWP-1A. Interestingly, most of the meltwater appears to come from the ancient ice caps of North America and Eurasia, with minimal contribution from Antarctica, reconciling once disparate views.

In addition to flooding vast swathes of lowland, this unprecedented release of fresh water into the ocean – comparable to the melting of an ice cap twice the size of Greenland in just 500 years – will have disrupted ocean circulation. , with ripple effects for the world. weather. Knowing the source of meltwater will improve the accuracy of climate models used to reproduce the past and predict future changes.

The results are important for our understanding of the ice-ocean-climate interactions which play an important role in the formation of terrestrial weather models. The results are particularly timely with the rapid melting of the Greenland ice sheet, contributing to sea level rise and changes in global ocean circulation.

Among the findings, lead author Yucheng Lin, from the Department of Geography at Durham University, notes: “Although it was identified over 30 years ago, it has been surprisingly difficult to determine which ice cap was the main contributor to this dramatic rise in sea level.

“Previously, scientists tried to determine the source of the sea level rise based on sea level data from the tropics, but the majority of these studies disagreed with the geological records of the change. of the ice cap.

Our study includes new information from lakes around the Scottish coast that have been isolated from the ocean due to land uplift following the retreat of the UK ice cap, allowing us to confidently identify the melt water sources. “

Co-author Dr Pippa Whitehouse, Department of Geography at Durham University, said: “The technique we used allows us to really dig into the error bars of the data and explore the scenarios of. most likely melting ice.

“We found that most of the rapid sea level rise was due to melting ice caps in North America and Scandinavia, with a surprisingly small contribution from Antarctica.

“The next big question is what triggered the ice melt and what impact the massive influx of meltwater had on ocean currents in the North Atlantic. hui – any disruption of the Gulf Stream, for example, due to the melting of the Greenland ice sheet, will have significant consequences for the UK climate. “

Rising sea levels due to global warming pose a great risk to society, improving our understanding of the reasons and speed of changes will help us plan for impacts.

The study is published in Nature communications.