2015 September NSIDC Extent Prediction

This is the prediction I will be submitting for the June Sea Ice Prediction Network 2015 predictions. I wasn't aware of the mid May call for early season predictions, as I use April data I could have put this in for that round.

Mid March 2015 Status

So far the sea ice extent maximum was set on 22 February 2015, however as of 13 March extent is only 0.14M km^2 below, so it is too early to claim a maximum. That noted there are good grounds to suspect that the 22 February maximum may hold. PIOMAS data is covered at the end of the post.

The Slow Transition: The Thickness Growth Feedback

PIOMAS data is often used in statistical extrapolation to support claims of an imminent crash of summer sea ice. However Zhang 2010 ("Arctic sea ice response to atmospheric forcings with varying levels of anthropogenic warming and climate variability" PDF) uses the very same model in a future projection and finds no such crash. What is going on? Which approach and conclusions are to be trusted?

The Slow Transition: Arctic Ocean Energy Gain.

The decline in sea ice volume can reasonably be viewed as a process of net energy gain in the Arctic Ocean's ice/ocean system. How can it be possible for the rate of volume loss to reduce, against the trend of past energy gain?

PIOMAS November 2014

PIOMAS data is out, so here's the usual analysis, with a bit of NSIDC Extent tagged on at the end...

The Slow Transition: Trendsetters.

Statistical extrapolation of volume loss has been used to make the claim that the Arctic sea ice faces a rapid decline to a state of summer open water within a few years, or at least this decade. Is this technique likely to give expectations that will be disappointed?

The Fast Transition

The peripheral seas of the Arctic Ocean are now virtually ice free in September, they are seasonal sea ice seas.

Need I say more?



It seems I do...

In comments Oale wanted to see this in terms of area, which is fair enough. I've done two graphs, one for area one for extent, both with a plot as percentage of April area and extent.

PIOMAS September 2014: Massive Volume Gain

The story of the 2014 melt season has been one of unexpected ice survival due to weather being largely unfavourable for largescale ice melt. Now, after a delay to NCEP/NCAR reanalysis data, the PIOMAS volume data is out and it is possible to see how much volume gain will be carried over into the 2014/15 winter, and very likely beyond.

PIOMAS July 2014

PIOMAS data is now out and the picture of another year of muted melt is confirmed. As of this June the net volume impact of the 2010 volume loss event has been wiped out. However this does not equate to a recovery of thickness or volume across the Arctic. Those still holding out for a crash this year are flogging a dead horse, those expecting a crash by around 2016 are walking towards the same horse, whip in hand.

The regional PIOMAS Data and Thickness Plots that I produce are now updated. See the top right panel on the blog for links.

The Slow Transition

I've been busy with the day job, which has given me time to ponder something I've hinted at before but am now firmly behind. This year isn't a major factor, due to my increased workload in the day job I've had time away from this subject doing something else (often repetitive and boring admin) that has let my subconscious work on the issue - the issue being the long term outlook for Arctic sea ice. Here is what I am now 90% convinced of, having entertained the scenario as a possibility over the last year or so.

April 2014 - Start of the new season

If PIOMAS Gridded data is published I will be posting thickness distributions based on grid box effective thickness, and any other resulting comments. However as the main series PIOMAS data is now out it's worth going over some points I want to raise. It's also worth reading Neven's summary of the past winter, and the May PIOMAS update.

What is the future of Arctic Sea Ice? Part 2.

In my previous post I discussed the results of model forecasts for Arctic sea ice, and have outlined why I am not convinced by GCM results suggesting long term survival of perennial ice well into this century. What happens if the current trend of sea ice losses continues and will the trend of volume loss continue?

What is the future of Arctic Sea Ice? Part 1.

Recently I blogged about a paper showing the cause of the post 1995 volume decline in PIOMAS, this being the period of greatest and most persistent volume loss. The cause turned out to be self-acceleration of volume loss caused by the ice albedo feedback, as this is such a fundamental process and as the later version of the PIOMAS has proven to be so successful, I am in little doubt that Lindsay & Zhang's hypothesis is correct and that in the 1990s atmospheric impacts on the ice ushered in a period of decline largely driven by the ice albedo feedback.

There is really only one issue I can move on to address now, and that is the future of the sea ice.

What caused the volume loss in PIOMAS?

Behind all of my blogging on sea ice is the volume loss, which is driving the changes. The volume loss is shown by other data (e.g. Submarine upward looking sonar, ICESat, IceBridge, Cryosat 2), but the most detailed picture is that provided by PIOMAS. What is driving the volume loss in PIOMAS and is this process at work in reality?

Sea Ice Thinning, Open Water Formation, and Ice Albedo Feedback

What is the link between the thinning of Arctic Sea ice and the increased open water seen in recent years?

PIOMAS Gridded Data: February 2014.

PIOMAS gridded data has been released for February giving some more detail about current ice state. The peak volume for the whole Arctic is in April, thickening continues in the central Arctic into May, so there is still time for thickening but I don't expect the volume to reach the high level compared to last year. The 2013 volume pulse seems to be largely spent.

PIOMAS February 2014

In terms of PIOMAS total volume the winter sea ice seems to have lost the 2013 volume gain. What might this mean for 2014's impending melt season?

The PIOMAS late summer anomaly increase.

In recent summers the late summer volume loss in PIOMAS has been less than in the past, why is this?

Autumn 2013

Now that PIOMAS data is out and a New Year has begun, it's worth going over some of the data regards sea ice, what I had intended to be my first post before the atmosphere going bonkers derailed my train of thought.

New PIOMAS Gridded Data: November 2013

New PIOMAS gridded data (effective thickness fields) has been released up to November, hat-tip to Wipneus for letting me know. So I've interrupted my blogging holiday to post on the new data which gives a great view of 2013 from the point of view of PIOMAS.

The regional PIOMAS derived data I have previously released, and which is used throughout this post, has now been updated through to November 2013, it is available in CSV files here. Thickness calculations have not been updated for 2013 because they need concentration which has not been released.

Once again, thanks to Dr Jinlun Zhang and colleagues at the Polar Science Centre for making the gridded PIOMAS data publicly available.