Posted BY: | NwoReport
n online friend of mine alerted me to a curious change in the Greenland Ice Sheet. From the Danish Polar Portal, here are two of their graphics.
Figure 1. Surface Mass Balance (SMB), polar year 2022-2023.
The Polar Portal site says:
The blue curve shows the current season’s surface mass balance measured in gigatonnes (1 Gt is 1 billion tonnes and corresponds to 1 cubic kilometre of water).
The dark grey curve traces the mean value from the period 1981-2010.
The light grey band shows differences from year to year. For any calendar day, the band shows the range over the 30 years (in the period 1981-2010), however with the lowest and highest values for each day omitted.
And what is the surface mass balance (SMB) when it’s at home? Again from the Polar Portal.
The difference between snowfall and runoff is known as the SURFACE mass balance. It is always positive over the course of a year as not all fallen snow runs off the ice sheet again.
The surface mass balance is NOT identical to the TOTAL mass balance (i.e. overall gain or loss of the ice cap), which also includes the mass that is lost when glaciers calve off icebergs, the melting of glacier tongues as they come into contact with warm seawater and frictional and other effects at the bottom of the ice sheet.
From my perspective, the oddity is that despite the warmer-than-usual conditions of the North Atlantic for this time of year, the surface mass balance has grown more than at any time in the period 1981-2010. Go figure.
One thing you can depend on the weather to do, and that is, it won’t do what you depend on it to do …
However, this is just the surface mass balance (SMB). The total mass of the Greenland Ice Sheet continues to decline. And here’s where the graphic trickery comes into play. Folks like the Polar Portal are more than happy to show graphs of the cumulative loss of Greenland ice.