New Risk Indicator: NSIDC Greenland Ice Sheet Melt Extent

All my career, I have been steeped in data and probably have an unhealthy ‘data dependency’. Moreover, I have a penchant for high-fequency data; that is, the daily or monthly numbers.

When it comes to climate, this could be viewed as an unhealthy fetish. For example, the World Meteorological Organisation defines climate as average weather over a 30-year period. That is all well and good if climate is so called stationary—in other words, its mean and variability isn’t changing through time. Obviously, this is no longer the case as we saw with Arctic sea ice extent last summer.

The National Snow and Ice Data Center (NSIDC) has now provided us with a new daily updated high-frequency time series, this time on Greenland melt extent, complete with daily images that can be found here. Click on the image below to expand.

Greenland Daily Melt jpg

The 2012 melt season was unprecedented, with 97% of the island showing melt at one stage in July. A review of the year 2012 for Greenland by the NSICD can be found here. The critical question going forward is whether 2012 was a true anomaly or a harbinger of the new normal.

A similar argument was voiced some years ago over the 2007 Arctic sea ice extent retreat, with most scientists at the time urging caution over calling a trend break and suggesting that 2007 could have been a product of an unusual confluence of weather factors. After the 2012 sea ice extent retreat, which smashed the 2007 record, few would now argue against the trend being truly broken (with Arctic sea ice extent now in a state of collapse). I fear we may see a repeat performance with Greenland ice melt over the next few years.

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