F.Tnioli wrote "I think you underestimate the power of Arctic insolation in June and July." Interesting, given I wrote nothing about July! Two of 15 years melting "massively" more ice in June than this year's June doesn't particularly challenge what I wrote. This doesn't mean I haven't under-appreciated "the power of Arctic insolation in June". I agree that the next PIOMAS data release will tell. I do wonder if the extra open water in May will compensate for the less-than-ideal-for-melting weather in June, as far as heat absorption in the Arctic goes.
I'll try to clarify it for you.
You wrote enough about June for me to suspect that you underestimate the cooling effect produced by larger-than-usual cloud cover in Arctic this June. This can only happen if you also underestimate the sheer power of insolation in compare to other melt factors of Arctic ocean's sea ice (warm water currents, warm air, rain, river runoff, etc). And if you do it for June, then i guess you'd also do it for July. So i mentioned both. Sorry if it was unnesessary, but i just hoped to remind by mentioning July that 1st half of July has nearly the same insolation as the end of June. Didn't expect it'd cause you to ask about it, but you do, so here you go.
Next, it's not just two years. If you'd look to the graph's notes, you'll see that there is a line for 2004...2013 _average_. And you'll see June 2016 line falls much slower than that average. And i hope you do know that 2001...2003 and 2014...2015 did not bring nothing which could shift that average line so much as to change our conclusion here. Which was, is and remains to be quite simple: according to DMI, volume loss this June (so far) is less than average, and very much so. Objecting to this is pointless. You will have much better luck pointing out how bad (wrong, incorrect, broken - pick your term) DMI volume graphs / data are; many have done so in the past, and not without reason.
From past experience, i find that PIOMASS and DMI volume data usually correlate in their dynamics rather well, despite the usual difference in absolute number. By this, i mean that IMHO it's very likely that PIOMASS will also report lower-than-average June when its June report will be published.
And as for your last doubt - no, it won't compensate. In reality, i doubt anyone could tell you for sure whether "lots of open water in May" in fact helps to melt more ice later during the melt season - or on the opposite, _prevents_ some ice from melting during later parts of the season. See, lots of extra open sea during May means that lots of extra water evaporated from its surface. Some of that vapour goes up and forms clouds, and Arctic upper athmosphere tends to stay in Arctic, vortex and all. And now, surprise-surprise, - we see very cloudy June. Coincedence? I doubt. There is definite negative feedback here. Of course, there are also positive feedbacks, too - some quite obvious, like lots of extra heat stored in Arctic waters as a result of May record low cover. But who can exactly quantify and find what's the end result - which feedbacks caused by "lots open water this May" are stronger? Who could calculate exact sum of positive ones and negative ones? I'm pretty sure noone can. And guesses may (and will) vary.
Which is why this forum remains useful. "One mind is good, but two minds is better" goes my people's proverb.