What a coincidence. Just like last month, I will have to precede the PIOMAS update with a short news flash that a very strong cyclone is barreling through the Arctic. But this time too, the cyclone will be short-lived, and so it's not entirely clear whether, on the whole, it will be damaging or beneficial. It has gone further into the Arctic this time.
Either way, the cyclone' has bottomed out at 968 hPa according to Environment Canada, which is just 2 millibar more than last month's cyclone:
With their sub-970 hPa pressures these cyclones come close to the Great Arctic Cyclone of 2012 (963 hPa), but I think they lack in other parameters such as longevity to really deserve the GAC epithet. Nevertheless, to see two of these monsters in June and July in what hasn't otherwise been a very noteworthy melting season so far, is quite noteworthy. We might even see another one before the melting season is over, which could be a sign of some yet to be identified change going on in the Arctic, causing these extremely warm winters, followed by relatively cold and cloudy summers.
But that's all speculation. Let's look at the updated PIOMAS volume numbers.
Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:
After a slightly below average June volume decrease (6199 km3 vs 6217 km3 for the 2007-2017 period), 2018 has dropped to 6th place. The difference with 2017 - lowest on record as of June 30th - has been reduced from 1916 to 1659 km3, but the gap with record-breaker 2012 has grown by a whopping 1097 km3. That's how much of a difference June can make, which shows how crucial this month is for the melting season.
Here's how the differences with previous years have evolved from last month:
Wipneus' version of the PIOMAS graph shows the 2018 trend line right in the middle of the post-2010 pack, already hinting at which trajectory it may take until September:
Even though 2018 isn't among the very lowest years, the trend line has shot down below the linear trend on the PIOMAS volume anomaly graph:
I had actually expected PIJAMAS average thickness to be lower, because JAXA was relatively high at the end of June, while PIOMAS is still holding up somewhat. Remember, PIJAMAS is a crude average sea ice thickness measure, which you get by dividing PIOMAS volume with JAXA extent. So, if JAXA is relatively high, average thickness should go down.
There is something of an abrupt downturn towards the end of June, but maybe this effect will be more pronounced next month:
I don't believe the Polar Science Centre thickness graph is showing anything out of the ordinary either:
A small addendum thanks to a series of fantastic regional volume graphs, posted by Oren over on the Arctic Sea Ice Forum.
What makes this melting season interesting so far, is that melting has been progressing relatively slowly the past few weeks, as expressed in the various extent graphs and the PIOMAS volume graphs as well. However, if we look into the distribution of melt by checking regional graphs, we notice that 2018 isn't far behind at all in those regions that determine the minimum (as opposed to the regions that melt out completely).
Take, for instance, Oren's PIOMAS volume graphs for the Central Arctic Basin and this inner core of the Arctic sea ice pack (Central Arctic Basin, Canadian Arctic Archipelago and Greenland Sea):
Wipneus has a couple of graphs showing extent and area of this inner core, without the periphery. The large graph shows the combined Beaufort, Chukchi, ESS, Laptev and CAB numbers in the Uni Hamburg, JAXA and NSIDC datasets, which all three have different resolutions, for the 2012-2018 period (NSIDC includes 2007). The lower two graphs show only NSIDC extent and area for said regions in the 2006-2018 period. For now, 2018 is among the lowest there too (click for a larger version):
Right now, the weather forecasts aren't pointing to any weather conditions that will melt the ice like crazy (as said, I'm not sure what the over-all effect of the current cyclone will be). If that keeps up, I expect the inner core numbers to start slowing down their descent as well. But I wouldn't exclude some minor surprises as of yet.
This melting season won't be breaking any records, but it's not entirely clear where it's going to end up. However, there's a good chance that the ice in the western Arctic is spared the worst, and this could potentially be good news for the ice.