A recent paper by Kent Moore et al. has caused something of a stir in the mainstream media recently, as well as in cryospheric circles and amongst the cryodenialista:
“First Observations of a Transient Polynya in the Last Ice Area North of Ellesmere Island“
The area to the north of Ellesmere Island and Greenland contains the Arctic’s thickest ice and it is predicted to be the last to lose its perennial ice, thus providing an important refuge for ice-dependent species. There is however evidence that this Last Ice Area is, like the entire Arctic, undergoing rapid changes that may reduce its suitability as a refuge. During May 2020, a polynya developed to the north of Ellesmere Island in a region where there are no reports of a previous development. We use a variety of remotely sensed data as well as an atmospheric reanalysis to document the evolution and the dynamics responsible for the polynya. In particular, we argue that anomalously strong divergent winds associated with an intense and long-lived Arctic anti-cyclone contributed to the development of the polynya as well as similar previously unreported events in May 1988 and 2004.
Curiously the paper neglects to mention a polynya in the same region that we reported on, albeit in passing, in August 2018. Here’s an updated video of that event, with the addition at the start of a yellow arrow to highlight the part of the Arctic’s “Last Ice Area” investigated by Moore et al. and a pale blue arrow to highlight Kap Morris Jesup, the most northerly point in Greenland:
Next here’s another animation, covering the time period discussed in the paper and continuing throughout the summer of 2020:
Comparing the two animations it is obvious that the August 2018 polynya is much larger than the one in May 2020, confirmed by a quick area computation using NASA WorldView:
The introduction to the paper states that:
Flaw leads, elongated regions of open water that develop along the interface between land fast and pack ice (Barber & Massom, 2007) are common in the region. Indeed Peary’s 1909 sledding expedition to the North Pole was delayed as a result of a large flaw lead that developed north of Ellesmere Island (Peary, 1910). However, the development of a polynya in this region has not been reported previously.
To my eye the image above reveals something far too wide to be described as a “flaw lead”, but let’s delve deeper into the paper:
A perspective on the unique nature of the May 2020 event is provided by the monthly mean area of open water in the area of interest during May for the entire period of the ASI data set, 2003–2021 (Figure 2h). Typically the area of open water during May in the region is less than 160 km2. May 2020 is the only year in which the area of open water exceeds 2 standard deviations above the mean.
Perhaps the polynya in question is indeed “unique in the month of May”, in which case it would no doubt have been helpful if the abstract and/or the introduction to the paper had mentioned this subtlety. Then the plethora of erroneous statements in the media like the one recently referenced by Mark Lynas on Twitter might have been avoided?
The polynya is the first one that has been identified in this part of the Last Ice Area, according to a new study detailing the findings in the AGU journal Geophysical Research Letters.
Since Mark, amongst others, seem to be suffering from the misapprehension that “The Arctic’s ‘Last Ice Area’ is cracking, just in time for COP26” here is what’s been happening in the “Last Ice Area” this year, in the run up to next month’s conference in Glasgow:
Finally, for the moment at least, are MODIS images of the May 20th 2020 polynya:
and the one on May 12th 2004:
Neither Aqua or Terra had been launched in 1988 of course, and Landsat 5 didn’t cover the north of Ellesmere Island. This is the SSM/I & SSMIS visualisation of all three May polynyas from the supplement to Moore’s paper:
