Gyldenlove Glacier, Greenland (Pic: NASA Goddard Space Flight Center)
Scientists ‘incredulous’ at abnormally high numbers for April, with melting across nearly 12% of ice sheet...
Polar researchers thought their models were broken when they first saw the results.
Almost 12% of Greenland’s ice sheet was melting on Monday, according to data crunched by the Danish Meteorological Institute.
It beat by almost a month the previous record for a melt of more than 10%, on 5 May 2010.
“We had to check that our models were still working properly,” Peter Langen, climate scientist at DMI, told blog Polar Portal.
Temperature readings on the ice were in line with the numbers, however, exceeding 10C in some places.
Even a weather station 1840 metres above sea level recorded a maximum of 3.1C, which data analysts said would be warm for July, let alone April.
Greenland’s usual melt season runs from early June to September. “Too much. Too early,” tweeted the World Meteorological Organisation.
The map (above) shows how much sunlight is reflected from the Greenland Ice Sheet. Bright areas reflect more sunlight than dark areas and as a consequence dark areas are heated more than bright areas. This phenomenon is known as the albedo effect.
The map is shown as anomalies, which means that the average of the albedo measured in the period 2000-2009 has been subtracted. In this way it can be seen where the ice is brighter and darker than normal.
Red areas indicate where melting and possibly black carbon from wildfire accumulating on the surface darkens the ice. Blue areas indicate where fresh snow or more snow than normal has accumulated. Albedo thus provides a convenient indicator of the competing effects of ice mass gain from snowfall and ice mass loss from melting. Melting ice tends to be darker (has a lower albedo) because melt causes ice crystals to round and if the melting point is reached, liquid water also lowers the snow and ice reflectivity. Any change in reflectivity thereby tends to amplify subsequent changes through a positive feedback loop. Thus, albedo is a very sensitive ice climate indicator.
The map is based on NASA satellite measurements from the MODIS sensor that measures the reflection of sunlight from the surface. The map is updated weekly. These types of measurements cannot be made in the winter season due to lack of sunlight. The animation shows the latest 50 days of available satellite measurements.
A trusted expert tells me: “The culprit driving melt at this time is an interesting omega pressure pattern with a very cold north America and warm air over Greenland.”
Little to no melt through winter is the norm as sub-zero temperatures keep Greenland’s massive ice sheet, well, on ice. Warm weather usually kicks off the melt season in late May or early June, but this year is a bit different.
Record warm temperatures coupled with heavy rain mostly sparked 12 percent of the ice sheet to go into meltdown mode (hat tip to Climate Home’s Megan Darby). Almost all the melt is currently centered around southwest Greenland.
According to Polar Portal, which monitors all things ice-related in the Arctic, melt season kicks off when 10 percent of the ice sheet experiences surface melt. The previous record for earliest start was May 5, 2010.
The summit of the Greenland ice sheet has also been record warm. On Tuesday, it reached 20.3°F (-6.5°C) which while obviously below freezing, is still record mild for this time of year and is roughly 40°F above normal. And the wamrth isn’t over yet.
Temperatures could reach as high as 57°F above normal this week. It’s distinctly possible more temperatures records could fall before the week is out.
By Megan Darby with Peter Sinclair
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