The Hot Zone

The seas are rising, but how much?

Posted by Alison Hawkes on October 3, 2010
Category : Climates of the Past

As the mercury continues to rise, we all know that the sea level is also going up. But by how much? Scientists do the best they can to model the impacts, and based on that policy makers have come up with the 2 degree Celsius limit to how much hotter the Earth can get and still be in the safety zone.

But what if they’re wrong? A paper published in the September Journal of Quaternary Science synthesized ice, marine, and terrestrial data from the last interglacial event, some 125,000 years ago, which was mainly driven by orbital changes in the Earth.

University of Exeter geographers Chris Turney and Richard Jones came up with a revised estimate of average global temperatures of 1.9 degrees C warmer than pre-industrial levels, which resulted in a whopping sea level rise of 6.6 to 9.4 meters higher than today. That breaks down to about 60 to 90 centimeters per decade, double that observed in recent years.

We know the seas are rising, but by how much? Photo: Franklin O'Donnell

Consider our current projection on a CO2 low emissions scenario and the comparison is startling. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change considers a 2 degree C temperature rise, resulting in a 0.18  to 0.38 meter sea level rise to be a best case scenario, and one increasingly unlikely given little attempt to curb the planet’s appetite for carbon. This estimate on sea level rise we know is low, since it excludes ice sheet flow due to the lack of data in published literature.

If the last interglacial is any indicator of what 2 degrees C gets us, we could be in for much higher seas than we ever imagined.

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