50% More Sea-Level Rise from Melting Glaciers

Climate has started warming, but it will take many years for glaciers to melt and catch up.  That means our world has already committed to a certain amount of sea-level rise.  You can't just turn off the spigot.

In this research we linked future changes in glacier volume (melting) to future changes in sea level.  Glaciologists divide glaciers into two zones – a high elevation zone where snowfall dominates and a lower elevation zone where melting dominates.  If there is more snowfall than melt, then glaciers advance and grow.  But currently observed snowfall zones are too small, and as a consequence 400,000 glaciers in the Alps, Alaska, Himalayas, and elsewhere will have to shrink and lose 27% of their volume to catch up with current climate.  As a result, melting glaciers will make sea level rise at least 18.4 cm even if the climate does not continue to warm.  If the climate continues to warm along current trends, a minimum of 37.3 cm of sea-level rise over the next 100 years is expected as glaciers and ice caps lose at least 55% of their volume.  That's about 50% more sea-level rise than previously estimated from glaciers and ice caps.

After additional contributions from the Greenland and Antarctic ice sheets, thermal expansion of the oceans, etc., the complete total will be even higher -- at least 80 cm of sea-level rise expected this century.  For perspective, that’s enough sea-level rise to break apart and drown many U.S. barrier islands.  Coastal aquifers, wetlands, and infrastructure will be threatened, and many pancake-flat island nations like the Maldives will fare even worse with much of their developed lands just 40 cm above the current high tide mark.

This research was published in Geophysical Research Letters and is available online at http://www.agu.org/pubs/crossref/2009/2008GL036309.shtml  Or download the preprint.

Bahr, D. B., M. Dyurgerov, and M. F. Meier (2009), Sea-level rise from glaciers and ice caps: A lower bound, Geophys. Res. Lett., 36, L03501, doi:10.1029/2008GL036309.


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