Sea levels rose by 18 metres when the ice caps last melted, study says


The melting happened at the end of the last ice age. (Credits: Getty Images)

Melting ice caps lifted the sea level by up to 18 metres (60ft) at the end of the last ice age, providing a stark warning of our future if today’s ice sheets continue to melt.

Scientists at Durham University discovered the ice sheet responsible for the huge rise, which lifted sea levels ten times faster than the current rate.

By analysing the geological records, researchers established that North American and Eurasian ice sheets made the water level rise at around 3.6 metres per century over half a millenium – contrary to the Antarctic ice sheet that many suspect.

The rise came right at the end of the last ice age, when ice sheets on the continent of Europe and the modern-day US retreated and melted, flowing into the oceans in what scientists call meltwater pulse 1A (MWP1a).

The vast amount of ice that melted would have been equivalent to an iceberg the size of Greenland melting in a 500 year time span.

Scientists say a sea level rise of this magnitude would have had huge knock-on effects on the world’s climate, and that understanding exactly how could guide today’s climate projection models.

‘The results are important for our understanding of ice-ocean-climate interactions which play a significant role in shaping terrestrial weather patterns,’ the scientists said.

The rise in sea levels happened mostly because of European and North American ice sheets melting. (Credits: Getty Images)

‘The findings are particularly timely with the Greenland ice sheet rapidly melting, contributing to a rise in sea levels and changes to global ocean circulation.’

Lead author Yucheng Lin said: ‘Despite being identified over 30 years ago, it has been surprisingly challenging to determine which ice sheet was the major contributor to this dramatic rise in sea levels.

‘Previously, scientists tried to work out the source of the sea-level rise based on sea-level data from the tropics, but the majority of those studies disagreed with geological records of ice sheet change.

‘Our study includes novel information from lakes around the coast of Scotland that were isolated from the ocean due to land uplift following the retreat of the British Ice Sheet, allowing us to confidently identify the meltwater sources.’

The technique that the researchers used will also allow scientists to make more accurate guesses about what happened in the last ice age.

‘We found that most of the rapid sea-level rise was due to ice sheet melt across North America and Scandinavia, with a surprisingly small contribution from Antarctica,’ said co-author Dr Pippa Whitehouse

‘The next big question is to work out what triggered the ice melt, and what impact the massive influx of meltwater had on ocean currents in the North Atlantic.

‘This is very much on our minds today – any disruption to the Gulf Stream, for example due to melting of the Greenland Ice Sheet, will have significant consequences for the UK climate.’


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