Melting momentum, it's what I call the absorption of heat and solar radiation during May and June that does not directly lead to melt and a reduction in ice cover, but rather comes into play during July and August (I had a more wordy explanation last year).
This is part 3 in the series.
As we saw last month, the melt pond fraction during May wasn't particularly high compared to previous years, and quite below that of 2012, effectively cancelling out the advantage that was built up on the extent charts. Back then it already looked highly unlikely that the 2012 record low minimum will be broken in September. This trend continued during June.
Dr David Schröder has been so kind as to send me the June melt pond fraction maps he uses for his SIPN 2016 Sea Ice Outlook prediction (blog post on June Report here). These results are based on the melt pond fraction simulation model developed by CPOM researchers at the University of Reading (more info). The comparison below shows melt pond anomalies for the years 2010, 2012, 2015 and 2016 compared to the average for the last 10 years:
Caveat: This is a model result, and so the distribution of melt ponds doesn't necessarily reflect reality.
The difference with 2010 and 2012 is clearly quite large. Just like last year May and June saw very little melting momentum being built up. Last year then caught up a bit because of one of the hottest Julys on record, eventually ending in third place with a September average of 4.63 million km2 (just like 2011, with 2007 and 2012 coming in at 4.30 and 3.63 million km2 respectively).
Dr. Schröder writes: