Monday 4 May 2015

April 2015 Status. Part 1.

This post is the first of two blog posts examining ice state as of April 2015. April extent is very low but this has little impact on the coming season. A greater factor is thickness and the thickness distribution of the ice, and the best available tool for that is the PIOMAS sea ice reanalysis system. Due to the length of this post I will address thickness breakdown of PIOMAS data using both grid box effective thickness and the sub grid thickness distribution in a post in the next few days.

However I will  start this post by stating the sum total of my findings with regards that more detailed data: I see an Arctic Ocean with two regimes, only the Central Arctic shows a gain in volume, the other regions show little difference from recent years, including April 2012. I also find little evidence of such an export of multi year ice into Beaufort, Chukchi, or the East Siberian Sea that would support my view that those regions are not likely to melt out this year. I may be about to change that view.

The fall of extent into summer is well underway, April extent is the second lowest on record behind 2007. But there is no reason to see that as an indicator for the summer season.

Extent for 2012 was ranked 21st lowest, while the top ten lowest April extent years are predominantly unremarkable years.

April Extent Year Rank
13.88 2007 1
13.96 2015 2
13.99 2006 3
14.1 2005 4
14.12 2004 5
14.18 2011 6
14.2 2014 7
14.23 1996 8
14.38 2002 9
14.38 2013 10

Looking at the situation on a regional basis I switch to anomalies. Anomalies are the difference from a long term average, here as usual I use the NCEP/NCAR reanalysis baseline of 1981 to 2010.

The red lines are the ranges between the highest and lowest extents for each region between 1979 and 2015 on 30 April. Okhotsk, Bering, and Barents are all near lowest recorded extent. The seas within the Arctic Basin, (Beaufort to Laptev), also Kara, Central and the Canadian Arctic Archipelago, are all near zero anomaly because extent is at maximum with full ice coverage over 15% concentration at this time of year.

A selection of seas playing a role in the current decline in extent are shown below.

Bering contributes to the record low April extent and has begun the drop to ice free conditions in line with previous years.

Meanwhile in the Atlantic, the Barents Sea is low through April and is on a trajectory towards dropping to near zero extent in the months to come.

Baffin Bay has had high extent all winter, this is associated with below average temperatures through April.

The Gulf of St Lawrence has had high extent through the winter, but is now dropping to zero.

Looking at the year so far in terms of sector extent, the Pacific sector (Okhotsk & Bering) has started to drop significantly. This has happened as temperatures over the region have crossed the 0degC threshold (NCEP/NCAR, not shown) and melt has firmly set in. The Canadian sector (Baffin, Hudson, St Lawrence) continues a fall since mid March. Hudson Bay remains topped out, the decline in the Canadian sector is wholly due to Baffin and St Lawrence.

Temperatures are shown in a composite plot from NCEP/NCAR reanalysis below, which shows the region north of 65degN.

Baffin Bay and St Lawrence (not shown) have been cooler than average through April (upper right quarter), While Barents Sea has been warmer than average (upper left quarter), this may be due to less ice than average not a cause of less ice. However across the pack through to Beaufort and Chukchi temperatures have been above average. While warmer temperatures may be caused by reduced sea ice extent or thickness they will also have a feedback effect, reducing the thickening of ice.

Overall this pattern of warming has led to the region north of 80degN being amongst the warmer years for April (surface temperature). 80degN is chosen to be comparable to the DMI temperature data.

Surface temperatures in the first third of 2015 north of 80degN in the NCEP/NCAR dataset are also amongst the warmest on record. This is in line with global GISS data for the first quarter of the year, e.g. Tamino's Open Mind.

PIOMAS gridded data is now available, however the main series of volume numbers don't seem to have been updated. Using the gridded data and my calculations, the average volume for the Arctic Ocean in April 2011 to 2014 was 19.39k km^3, April volume for those years was quite flat being within +/-0.2k km^3. April volume for the Arctic Ocean in April 2015 is 1.26k km^3 above the average for the preceding four years, a substantial gain of volume. The volume increase for the Central Arctic over the average April volume for the preceding four years is 1.44k km^3, more than accounting for the overall volume increase and showing that the volume increase is still restricted to the Central Arctic, in line with behaviour since last September.

The post 2010 April thickness maps are shown in the following animated gif. In producing that the images were accidentally arranged in reverse order, which hasn't turned out too bad given that 2015 state is the focus.

2015 shows a large expanse of ice over 2m thick through from the Central Arctic to Beaufort, Chukchi and the East Siberian Sea. However, as shown below, the volume difference between April 2015 and April 2013 (after the 2012 crash) shows that 2015 has marginally less volume in Beaufort, Chukchi, and the East Siberia Sea. The bulk of the volume increase remains in the Central Arctic region, and the map plot above shows that this is from the Central Arctic close to the Canadian Arctic Archipelago.

The volume series for all regions within the Arctic Ocean in April shows that the main region with a convincing increase in volume is the Central Arctic (the scale for the Central Arctic is on the right and is 4.5 times as large as that for all other regions on the left vertical axis). The Canadian Arctic Archipelago also shows an increase that is not as proportionately large.

Turning now to the breakdown of volume with grid box effective thickness.

The volume increase is seen to be largely due to grid boxes reporting a thickness of 4m and above. These are grid boxes north of Canada.

Looking at some other data sources. The US Navy's HYCOM-c-ice model shows an intrusion of thick ice into Beaufort/Chukchi and the East Siberian Sea. This is also seen in the Drift Age Model.

Furthermore the ASCAT scatterometer satellite reveals it, as seen in the following adapted image with contrast adjusted to bring out the white thicker multi year ice.

However the numerical data from PIOMAS do not suggest that this is a sufficient volume of multi year / thicker deformed ice for it to be a major factor in this seasons melt.

With the increase in volume largely restricted to the Central Arctic, conditions in the peripheral seas of the Arctic Ocean are similar to other recent years, including April 2012. I will detail this with more graphs in my next post. However looking at the PIOMAS sub grid thickness distribution numerically, if I use the demarcation of above 3.3m thick, there is an April 2015 volume of 1.48k km^3 (for ice over 3.3m thick) for the peripheral seas of the Arctic Basin (Beaufort round to Laptev), this is the second lowest volume in the post 2007 period. Whereas for the Central Arctic region, sub grid thickness volume over 3.3m thick is 5.87k km^3, that is the highest in the post 2007 period and is 3.6 standard deviations above the 2007 to 2014 average April volume for sub grid thickness ice over 3.3m thick.

HYCOM, the Drift Age Model and ASCAT all may be taken to indicate survival of ice extent long into the summer, but they don't give hard numbers. If PIOMAS is right, and it's been reliable so far, this raises the prospect of a more exciting season than I had anticipated, much of what happens will be in the weather. However it is a matter of judgement as to what importance one assigns to each of the data sources, and I need to think some more before commenting further.


AZ1971 said...

Great data. But absolutely no correlation to increasing temperatures and CO2 levels marking the return of sea ice volume thickness, which is what will be precisely argued this summer in Paris at the climate talks. If the return of PIOMAS volume runs counterintuitive to projections of effects by increasing CO2, then it needs explaining.

Chris Reynolds said...

Nothing counter-intuitive at all.

The recent increase in volume has been caused by weather, that is all. The effect of AGW and CO2 is not in doubt.

The Paris Climate Talks (first I've heard of them) will come to nothing in spite of the evidence, not because of it.

FishOutofWater said...

Warm water has pushed northwards into the Barents sea and into the Bering sea as El Nino has strengthened from weak to moderate and while a huge Kelvin wave is hitting the west coast of the Americas. This surge will likely bring on a super El Nino like 1997-1998 and 1982-1983. Expect a warm summer in the Arctic and expect warm waters to flow into the Arctic from both sides.

The central Arctic ice will hold out because it is thick but the rest of the pack will melt out. I think we will see a new minimum JAXA extent.

Record high global temperatures with the El Nino will be the talk of the climate talks, and, yes, they correlate with CO2 and CH4.

AZ1971 said...

FishOutofWater ... remember that correlation is not causation. Increasing CO2 cannot explain the increase in Antarctic sea ice extent, the recovery in PIOMAS Arctic sea ice volume, or the virtual standstill in global temperatures since 2000.

Chris Reynolds ... from your link, "the [volume] decline has been staggering and it is clear why even a single year like 2013 is insufficient to break the trend of losses, the Arctic would need a succession of cold years to increase volume and start to rebuild the ice, bucking the trend and starting a recovery. But that is not going to happen." Yet that's precisely what we've seen: PIOMAS shows an Arctic recovery of 30% since 2011. Weather patterns could not be maintained for such a long time without washing out ice through the Fram Strait at some point in time. And if albedo controlled the Arctic, what does increasing albedo in the SH say about effects at the other pole? Regardless, it doesn't explain the sudden reversal in PIOMAS volume, so there has to be some other explanation besides AGW.

Anonymous said...

"However looking at the PIOMAS sub grid thickness distribution numerically, if I use the demarcation of above 3.3m thick,..."

Is there a reason you chose 3.3 m?

Visually, the maps indicate an increase of blue (+2m) area, particularly in Beaufort and Chuchki. Isn't that the benchmark used by Lindsay & Co. to predict summer melt? Why not use 2m or 2.5m?

The PIOMAS track record is to under-predict the amount of very thick ice as compared to data from direct measurements. That suggests the relative difference from the recent low years is likely greater than the levels indicated.

Chris Reynolds said...


20/20 hindsight will gain you no points on this blog. If that's the standard you work to may I suggest Watt's Up With That?

We have had two years with poor melt. I need more than that to conclude that there is a regime change. If we have two more years I will be strongly suspecting a shift in the AMO as the root cause. Right now I await developments.

Sorry, I'm too busy with the northern polar sea to look at the Antarctic.

Chris Reynolds said...


In that paragraph I am using PIOMAS sub grid thickness distrbution, see my recent post 'What is PIOMAS gice for a detailed discussion.

However the distribution is given in this graphic from one of the papers describing the PIOMAS model.

From that you can see that the 2m thickness falls into the 1.93 to 3.30m band, nominal thickness 2.61m. So I have used the upper limit of that band after examination of the data confirmed my suspicion that it would be a reasonable choice. That thickness (3.30m) should encompass mainly first year ice below it, with mainly deformed ice and multi year ice above it.

Chris Reynolds said...

By the way Vindaloo,

Note in particular:

"2) At a party someone runs a nylon comb through their hair and amazes the denialist by picking up bits of tissue paper with the comb. Inspired by this, the denialist concludes that gravity is a liberal conspiracy, a great lie devised by so-called scientists, he blogs on this (it's normally a 'he'), hammering home the point that the scientific consensus on gravity is a socialist inspired fraud."

Just as gravity is still active when electrostatic forces oppose it, so the forcing from CO2 is still active when other factors cause a 'pause'.

FishOutofWater said...
There is no slowdown, hiatus or whatever you want to erroneously call natural variability. There was a super El Nino followed by some years that had more La Ninas than average. Anthropogenic global warming has continued unabated for the past 40 years. If statistics is too tough for you than you can see the unabated heating of the oceans in multiple reports on ocean heat content.

This situation in Antarctica is actually quite dire but fools think it's good news that sea ice is increasing. Glaciers around Antarctica are melting at a depth of 100 meters below sea level and freshening the surface water. That's actually causing the intermediate levels of the southern ocean to retain heat in the winter. What's happening in Antarctica is frightening to anyone who understands it.

Chris Reynolds said...

Fish Out Of Water,

I hope you're right regards your prediction of a warm summer. I could do with an exciting summer. :)

AZ1971 said...

Chris Reynolds,

"20/20 hindsight will gain you no points on this blog."

20/20 hindsight is the only way to accurately analyze historical processes of Arctic volume and extent, and is how the whole AGW topic has been brought about - to explain a trend of upwards temperatures during the 20th century. Adjusting data records to solely cool the past to make current warming more pronounced borders on outright deceit because it violates statistical probability.

"We have had two years with poor melt. I need more than that to conclude that there is a regime change. If we have two more years I will be strongly suspecting a shift in the AMO as the root cause."

Do you agree then that AMO/PDO is primarily responsible for NH climate variation and supersedes AGW claims of CO2 forcing?

AZ1971 said...

Chris Reynolds,

"Just as gravity is still active when electrostatic forces oppose it, so the forcing from CO2 is still active when other factors cause a 'pause'."

Which "other factors" are you referring to that are causing the 'pause'?

The skeptical debate centers on just how much of a climate forcing CO2 has in the real world. The UN IPCC presumes it is of value 'x' and models projections based on it. Since the real world hasn't matched modeled projections, it is fair to assume the climate forcing of CO2 is far less of a factor than currently believed.

AZ1971 said...


"This situation in Antarctica is actually quite dire but fools think it's good news that sea ice is increasing. Glaciers around Antarctica are melting at a depth of 100 meters below sea level and freshening the surface water."

Two things:
1. It is good news because of the increased albedo effect going into the SH summer, which reflects ~90% of incoming solar insolation of 1366 W/m2. That, in turn, reduces atmospheric IR retention.

2. Antarctic SST are at or near 0 to -1.5 Celcius. No melting is occurring at that temperature of surface ice. It is unreasonable to suggest any melting at depth ~100m is from upper-surface waters above -1.5C but is reasonable if from subterranean volcanic venting, which has nothing to do with AGW.

Chris Reynolds said...

Vindaloo Bugaboo,

No further comments from you are welcome. I don't want to turn on moderation, I don't like deleting comments, I prefer free and open discussion. But you are not interested in discussion, you are only interested in disruption.

I have shown you several blog posts. You then say:

"Do you agree then that AMO/PDO is primarily responsible for NH climate variation and supersedes AGW claims of CO2 forcing?"

This makes it clear that you are incapable of understanding the evidence, or of reading.

In this blog post, to which I referred you on 5 May:

I included the following graphics.

From the latter it is clear that there is scant relationship between the AMO and the Chapman long extent series.

From the former it is clear that only CO2 increases show a clear correlation with sea ice decline. Correlation is not causation, but where mechanism exists correlation is a useful tool to show what factor drives the change.

In any case in this post, which I also directed you to on 5 May:
I included a plot from a paper, that plot shows that in all models considered sea ice only declines when human factors, notably the increase in CO2, are included.

Other evidence aside the evidence shows that only an idiot would come to the conclusion that human driven global warming, as indicated by CO2 increases, are not causing the current loss of ice.

Anybody involved in studying Arctic sea ice, be they amateur or professional will have statements of what may happen in the future proven wrong by events. As we are all (amateur and professional) at risk of this we act as adults and treat such failures with respect. Sneering as you do is infantile.

You ask:
"Which "other factors" are you referring to that are causing the 'pause'?"

Yet prior to you writing that, on 6 May I directed you to a blog post. In that post I listed four papers:

Kaufman et al, 2011, Reconciling anthropogenic climate change with observed temperature 1998 to 2008.
Foster & Rahmstorf, 2011, Global temperature evolution 1979 to 2010.
Kosaka & Xie, 2011, Recent global-warming hiatus tied to equatorial Pacific surface cooling.
Cohen et al, 2012, Asymetric seasonal temperature trends.

So why are you asking the question when you have already seen the answer? It is clear that you have a conclusion already and are not at all interested in sceptical thinking, the hallmark of which is allowing the evidence to guide your conclusions.

You also show a total lack of grasp, in your dealing with me you say:
"Since the real world hasn't matched modeled projections, it is fair to assume the climate forcing of CO2 is far less of a factor than currently believed."
It is evident from your answers to FishOutOfWater that you show the same lack of grasp.

As Tamino has shown repeatedly, and as indeed the case. The mathematical tool for establishing a break from the forced trend is establishing if the 'pause' reaches statistical significance. By no measure does it do so. Therefore the 'pause' does not break the trend and does not bring the models or theory into question.

With regards the Antarctic, you need only enter a search term into Google to get a factual explanation:

Everything else you say on the matter shows your complete lack of comprehension.

I advised you earlier to go back to Watt's Up With That, or somewhere else with equally low standards. Further posting by you on this blog will be a waste of time as I will delete as soon as I see the comments.