Ocean level rise is known as one of the most disquieting effects of global warming, with more than three billion people living on the coast or less than 200 kilometres land inward and one tenth of the world population living less than 10 metres above sea level. But since many climate change related factors can influence it, sea level rise is also one of the hardest global warming effects to predict.

To see what may happen scientists of CEREGE laboratory and the Universities of Tokyo and Oxford have studied the largest known ocean level rise: Melt-Water Pulse 1A. They found that during a relatively warm period called the Bølling Oscillation roughly 14,650 years ago sea levels rose an average of 14 meters in just 350 years.

Per year this means a rise of 40 millimetres which makes the current approximation of sea level rise of 3 millimetres pale in comparison.

Not just the ice caps on the Northern hemisphere

It was previously assumed that only melting ice from the Northern hemisphere contributed to the sea level rise of Melt-Water Pulse 1A. But the sea level reconstructions published in Nature based on fossilised corals and geophysical simulations indicate that the Antarctic ice cap must have played a highly significant role as well.

Not only has the new study shown that a significant ocean level rise can occur over a surprisingly short time span, but the synchronicity between the Bølling oscillation and Melt Water Pulse 1A has shed light on the effect of a massive oceanic inflow of fresh water on the thermohaline circulation and the concurrent influence on global climate.

It demonstrates that a major climatic disturbance can set a complex reaction of the ice caps in motion that is harder to predict than previously assumed.

© Jorn van Dooren | www.bitsofscience.org