Naturally, we are concerned with the conditions of the GIS. First, because it is a factor in the world's weather and most North Atlantic icebergs originate here, but because it is a indicator of how the climate is going. Unfortunately, we see one more indicator of global warming going on here.
We would expect to see melting and freezing in the ice sheet due to the seasons, and that is what we see. Some of the ice melts in the summer and then snow is deposited in the winter. In addition to that, we also see that the amount of melt in the summer is greater than the amount of deposit in the winter. Take a look at this graph here:
|Source: Polar Portal|
By the way, this occurred during the period when deniers have insisted there is no global warming. Once again, we see facts put the lie to their claims.
So, how are things going this year? Again, not good. Take a look here:
And the forecast for additional melting? It is difficult to make a good forecast, but there is one thing that troubles me. Look at this plot.
|Source: Polar Portal|
This plot shows the albedo relative to the long-term average. Albedo is the measure of how well something reflects light. Something with an albedo of 1 (or 100) is a perfect reflector. An albedo of 0 means it reflects nothing at all - it would be perfectly black. Red areas on the above plot show where the current albedo is lower than the long-term average. Blue areas show where the current albedo is higher than the long-term average. The lower the albedo, the worse the surface reflects light and the more light it absorbs, leading to increased melting. Blue areas mean the albedo is higher and reflects light better, so melting would be reduced compared to the long-term average. The plot is not encouraging. There are some areas that are colored blue, but some shade of red dominates the plot area.
What could cause the lower albedo? There are two things that have been linked to this. One is soot from fires, the other is melt ponds. As we have more forest and wild fires due to climate change, the soot is carried on the winds and some of it is deposited on the GIS, lowering the albedo. Then, as the ice melts and forms ponds of water, the albedo drops even more because ice is a good reflector, but water is a good absorber.
Combining this data and the melting trend so far makes me think this will be a bad year for ice melt on Greenland. The summer of 2012 was the record bad year, hopefully we won't get that bad.