Do you want ice with that?

A popular pastime amongst those of us who have an interest in what's going on with the climate is to try to guess how much Arctic sea ice there will be each season when the annual minimum is reached.

For anyone reading who thinks this might interest them, there is an almost endless ongoing source of information, graphs and analysis at the excellent Arctic Sea Ice Blog/ Forum/Graphs.

There is also a science program which collects various predictions, from the technical (model-based) to the amateur (heuristic), called SIPN (used to be ARCUS).

Part of the fun of this is to try to work out the different factors which may or may not affect future sea ice level down the line. On a long time scale, this is easy enough, if you simply reference the climate data since 1979 and look at the history of decline in Summer sea ice levels. It is quite possible to do a 'rough fit' with historic data and come up with a prediction which is not far off the mark, though this is going to be more by chance than reason.

One of the most popular sources of data and information is the NSIDC dedicated sea ice and cryosphere pages. These focus on the measured data rather than prediction, but contain a wealth of useful graphics and links.

On the recent page you will notice a reference to a recent piece of research conducted by some of the members of the team, Serreze M. C. et. al., JGR (2016).

This paper demonstrates a connection which has an effect on the annual minimum:

"...They found that 68 percent of the variance in the date that ice retreats from the continental shelf break in the Chukchi Sea in spring can be explained by fluctuations in the April through June Bering Strait oceanic heat inflow..."


So, one way in which we can now make a more reliable prediction in relation to one part of the Arctic is in place.


Then, I noticed (not reported widely elsewhere yet) that others of the team have been involved in a different piece of research at the opposite side: Fram Strait sea ice export variability and September Arctic sea ice extent over the last 80 Years. (Smedrud et.al.). Here we find the useful:


"...Increased ice export during winter will generally result in new ice growth and contributes to thinning inside the Arctic Basin. Increased ice export during summer or spring will, in contrast, contribute directly to open water further north and a reduced summer sea ice extent through the ice–albedo feedback..."


and: "...We find a general moderate influence between export anomalies and the following September sea ice extent, explaining 18 % of the variance between 1935 and 2014, but with higher values since 2004...".


These two useful recent pieces of work add to our understanding of two of the mechanisms which contribute to Arctic Summer minima. They don't give the whole picture; the number and range of the variables are such that we don't have a full picture of all of the teleconnections or causes.


What we can do, though, is look at these two parameters and add some inferences to our other observations. If Fram export has been relatively high recently, then the September minimum is likely to be lower than the long term average. If Bering Sea heat input is higher than usual during the Spring, then the Septemberminimum is likely to be lower. 

If both cases occur simultaneously, it is reasonable to infer that there is a high likelihood of a reduced minimum, if the other other known variables (such as the Arctic oscillation - AO) do not contradict this, and if the historic patterns of weather and overall seasonal temperature anomalies are also in alignment.

This is an example of how ongoing scientific research and information collecting adds to our understanding of the ways in which the climate can vary, and the trends which show how the climate is changing relative to the past.

Sea ice, sea level and permafrost

Recent updates all over the place point out that Arctic sea ice levels are pretty low considering the time of year. Historically, the rate of decline of Winter Arctic sea ice cover (area, extent) is slower than that of the Summer (and the intermediate seasons). This year, the maximum so far (as pointed out at Neven's excellent blog, the finale is not yet concluded for certain, rather like a Tchaikovsky symphony) is below two standards deviation from the long term average. (here)

I don't subscribe to the notion that one season's extent is indicative of following seasons, for the simple reason that the range of inter-seasonal variability exceeds the range of climate variability. In other words, it isn't enough that there isn't much ice now to determine how much there will be at the end of this Summer (if only it was that easy!). But here we see the fortification (or continuation) of an existing and persistent trend, a reminder that we are apparently set into a pattern for the long term.

Meantime, Down South, recent observations (not yet officially published) are that the Larsen C ice shelf, thought to be stable when assessed in 2010, is now showing a big crack comparable to the one which preceded the loss of Larsen B some years back. Unlike some media, I won't publish more till the original is published, but you can check out the discussion paper at The Cryosphere.

Add to this the recent material illustrating the instability of the Totten Glacier in East Antarctica, the latest of a run of observations done in different parts of the EAIS showing a trend towards likely destabilisation (At least 4 papers recently on different glaciers).

Looking at a couple of other papers (I'll have to go find the sources at some point) I was caught by surprise when it was noted that the potential for sea level rise from the melting of permafrost is potentially very large (over time and relative to scale) and that permafrost is indeed melting reasonably rapidly across all Arctic landmasses (and, one supposes, potential under the ocean as well).

Which is all apropos of what?

One looks at a range of things and extrapolates a pattern. The apparent pattern is that a lot of the markers which might indicate an accelerated rate of sea level rise are all pointing in the same direction, and furthermore, that the observations of the changes are imminent, not down-the-line projections. For some time I've said, along with Rasmus Benestad and others, that the current 'mainstream' estimates of SLR are on the low side. 

I'd like to see a concerted effort to assess recent developments in observations and evidence as a whole and a review of the conclusions. IMO the odds of a 1 metre rise by the end of the century are now much shorter than they would have been twelve months ago. if a reader can point me to any material on the projected contribution of permafrost melting to SLR, that would be helpful, too.