By Javier
A year ago I wrote an article at WUWT analyzing the recent upward trend in summer Arctic sea ice extent. Despite challenges of statistical irrelevancy, the trend has continued another year. Arctic ice experts, that have repeatedly predicted the demise of summer ice, don’t have an explanation for a 10-year trend that contradicts their predictions, beyond statistical variability or unexplained natural variability. They believe the upward trend will end any year, and there were high expectations that 2017 was going to be that year, due to the low maximum in March. As we will see a low maximum has no predictive value.
However, the upward trend was predicted by Divine & Dick in 2006, based on the analysis of Nordic sea melt-season ice changes for the period from 1750-2002, where they identified two periodicities of ~60-80 years and ~20-30 years.
“… our results suggest that the Arctic ice pack is now at the periodical apogee of the low-frequency variability. This could explain the strong negative trend in ice extent during the last decades as a possible superposition of natural low frequency variability and greenhouse gas induced warming of the last decades. However, a similar shrinkage of ice cover was observed in the 1920s– 1930s, during the previous warm phase of the LFO [Low Frequency Oscillation], when any anthropogenic influence is believed to have still been negligible. We suppose therefore that during the decades to come, as the negative phase of the thermohaline circulation evolves, the retreat of ice cover may change to an expansion.”
So, when nearly every expert was predicting the collapse of Arctic summer ice, these two Norway-based researchers correctly predicted the trend observed for the past 10 years.
In science your hypothesis can only be correct if it not only explains, but also predicts the behavior of the studied phenomena. Therefore, the hypothesis of Divine & Dick is superior to the more popular hypothesis that assigns sea-ice behavior to the anthropogenic effect. For this year’s article I have decided to examine the hypothesis of Divine & Dick to analyze the importance of natural variability on summer Arctic sea ice evolution.
I am using NSIDC monthly Arctic sea ice data for March and September available here. The data are plotted in figure 1.
Figure 1. Arctic sea ice extent
Then I define the melt value for the year X as the September X value minus the previous March X value, resulting in a negative number. The refreeze value for the same year X is the March (X+1) value minus the previous September X value, resulting in a positive number.
Plotting the Melt and Refreeze curves on the same graph produces the amazing result shown in figure 2.
Figure 2. Arctic sea ice melt-refreeze cycle.
Both curves are very close. So close that the winter growth in Arctic sea ice is >80% predictable based only on the ice extent lost in the previous melt season. In fact, I can predict that the Arctic will gain between 9.3 and 9.7 million square kilometers from this past September to March 2018.
I’m not sure how surprised you are by this result. I don’t doubt this must be known by plenty of ice researchers, but I haven’t seen it reported anywhere despite reading a great deal about Arctic Sea Ice. This result leads up to some very important conclusions:
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Arctic sea ice dynamics are driven by unpredictable melting. Freezing is reactive and largely predictable.
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This indicates a very strong negative feedback in action. A small melting is followed by a small refreezing, and a huge melting by a huge refreezing. Surprisingly this is not known by many ice experts that expressed surprise after the huge refreezing that followed the huge 2012 melting.
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The negative feedback stabilizes sea ice. Alarmism and spirals of death are unjustified.
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The much-touted albedo effect can only have a small effect in the Arctic, as the lost ice is recovered during the following “dark” season, during which albedo has no role. An example that evidence always trumps logic.
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Inter-annual changes in sea ice are due to the small residuals indicated in the figure by the colored areas. Red for decrease and blue for increase.
- Around 1998 Arctic sea ice changed its dynamics and entered a period of higher volatility. One possibility is that below a certain size the Arctic sea ice sheet becomes more unstable and sensitive to weather phenomena.
To continue, we must concentrate on the annual difference between melt and refreeze. I define the anomaly for a year as the summation of the melt that occurs on that year and the refreeze that starts on that year and ends in the next year. This produces another amazing chart.
Figure 3. Arctic sea ice extent anomaly
The anomaly graph is very homogeneous for the 38-year period analyzed, despite huge changes in Arctic sea ice. So, there are more interesting conclusions to be extracted from the data:
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The yearly anomaly appears to be range bound. No positive or negative changes bigger than 600,000 square kilometers are observed.
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Despite periods when the anomalies are skewed towards one side, overall the observed linear trend is flat at –53,000 square kilometers/year. This means no acceleration of the Arctic sea ice loss is observed for the 38-year period, during which atmospheric CO2 levels have increased enormously to values not observed in over a million years.
- This result supports the hypothesis that cyclical changes in ice cover, over time, average out. As opposed to the hypothesis that ice cover loss is accelerating due to an increasing anthropogenic effect.
Since the loss of ice during the melt season is the driving factor in the Arctic sea ice dynamics, I have constructed a very simple model to explore the relationship between natural and anthropogenic factors in Arctic changes. The model rests on unproven assumptions and is not intended to represent or predict Arctic sea ice changes. It is simply a learning tool that uses several of the proposed mechanisms acting on ice. The main assumption is that to be observable above the high noise of September ice data, the four main factors, thought to participate in the process, must be between 15 and 33% responsible for the observed changes.
Figure 4. Components of the Arctic sea ice melt model
The first component (A) is a 21.33-year sinusoidal oscillator that is set to explain 25% of the observed variability.
y = (-0.25) sin 0.2944 (x)
The lows of the cycle are identified at 1990 and 2012 based on local minimum ice values.
The second component (B) is a 65-year sinusoidal oscillator that is set to explain 33% of the observed variability.
y = (-0.35) sin 0.096664 (x+24) – 0.306
The low of the cycle is placed at 2007, when the current upward trend started, and when North Atlantic sea-surface temperatures started to decrease.
The third component (C) is the anthropogenic factor based on atmospheric CO2 changes. It is set to explain 24% of the observed variability.
y = 0.5 – 3.2 Ln ([CO2]/290)
The fourth component (D) represents the long term natural variability, since the end of the LIA. It is essentially the ~ 1000-year cycle. Since it is very long term, it can be adequately represented for a short period with a line that is set to represent 17% of the observed variability.
y = (-0.34/32) x + 21.04
The model is initiated at 1980 at a melt of –8.1 million square kilometers
Such a simple model is not expected to adequately represent a complex phenomenon that likely responds to many more factors, but it reproduces the general shape and behavior of Arctic sea ice melt, and compares well with a polynomial fit to the data.
Figure 5. Arctic sea ice extent melt.
By comparing figure 5 and figure 1 we can see that the melt graph is extraordinarily similar to the September extent graph. As we have seen, Arctic sea ice dynamics are driven by the melting. The model therefore can be set to reproduce and project September Arctic sea ice data into the future. For that I have used RCP 4.5 scenario that contemplates a stabilization of CO2 levels at around 540 ppm soon after 2100.
Figure 6. September Arctic sea ice extent.
While I don’t expect future Arctic sea ice data to follow the model, I do expect it to perform better than the models that are based mainly on anthropogenic factors. As I said the goal of the model is to examine the possible effect of the different natural and anthropogenic factors on sea ice dynamics. It can be seen as a graphical representation of Divine & Dick hypothesis with fictitious but reasonable values.
I do believe we are entering a period of Arctic sea ice stabilization, and even expansion, that should last until around 2042, and this is a prediction in stark contrast with IPCC’s ice models that see an end to summer Arctic sea ice by 2040-2080 for most scenarios and near constant decline until then.
High sea ice variability could produce some ice-free summers around 2075, but the conditions for the existence of summer Arctic sea ice are likely to remain for the foreseeable future. By 2100, atmospheric CO2 levels are expected to stabilize in the more credible RCP 4.5 scenario, and the millennial cycle is expected to change phase, so there won’t be a net negative ice driver. From then on, Arctic sea ice should start growing for many centuries to come.
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Great article, Javier, and many great comments. Very interesting thread.
There is no upward trend in summer arctic ice.
The volume and thickness consistently declines: this year’s extent was in lowest 3 till near end of August.
and there’s a downturn in winter ice… it is freezing with the same lack of speed we saw last year and heading further towards ‘lowest x for this date’ territory
Griff, you are denying the reality of climate change.
Unlike ice extent that is measured, ice volume is modeled. No point in trusting a computer output over what our satellite eyes see. It is unlikely that the Arctic ice sheet is transitioning from a pancake to a crepe.
Do you care to predict next year minimum to see if you fail as spectacularly as this year? I have shown my prediction of a continuation of the current upward trend to 2022.
Ice volume is also measured…
It is checked against observations…
http://psc.apl.uw.edu/research/projects/arctic-sea-ice-volume-anomaly/
“Comparisons of the model estimates of the ice thickness with observations help test our understanding of the processes represented in the model that are important for sea ice formation and melt.”
All the different sets of data (many of which are checked by direct observation) show thinner ice
Observations by whom? There’s nobody in the Arctic and it’s huge. And checking against observations is proof that is not measured. Extent is not checked against observations because it is an observation.
Why are we going to believe the volume, when we have the extent that is measured?
Are we supposed to believe that when extent is growing year after year, the non-measured volume is going down?
The believers are truly capable of believing anything. Hey, Griff, I have a book that was written by God himself. The consensus agrees on that. Are you interested?
Griff the all unknowing arctic ice non-expert.
On the DMI site it says their volume is modeled!
Poor Griff, Climate change deniêr extraordinaire.
You KNOW that current levels are FAR above any time in the large 10,000 years, apart for the Little Ice Age , and the late 1970s (which had similar extremes.
Why do you continue to DENY CLIMATE CHANGE?
Why do you continue to DENY that the world is really just a small amount warmer than the COLDEST period in the last 10,000 years?
Arctic sea ice stable since 2005
http://www.woodfortrees.org/plot/nsidc-seaice-n/from:2005.3/to:2017.3/plot/nsidc-seaice-n/from:2005.5/to:2017.5/trend
“I’m not sure how surprised you are by this result. I don’t doubt this must be known by plenty of ice researchers, but I haven’t seen it reported anywhere despite reading a great deal about Arctic Sea Ice.”
Yes here at Climate Etc last year, you are on the same comment string:
https://judithcurry.com/2016/09/18/is-the-arctic-sea-ice-spiral-of-death-dead/#comment-812117
I was aware of the negative feedback that more open water leads to more freezing. Everybody knows that. What I was not aware was how close the melting and the refreezing are. The two curves practically overlap.
Apparently not. Your words:
“This indicates a very strong negative feedback in action. A small melting is followed by a small refreezing, and a huge melting by a huge refreezing. Surprisingly this is not known by many ice experts that expressed surprise after the huge refreezing that followed the huge 2012 melting.”
I have talked about the insulating effect of ice and the loss of heat by open ocean several times previously. It is the close match between melting and refreezing leaving only a small residual what I was unaware. One has to look at the data to see that the recovery is all done in a single season, and not spread over several.
Certainly you have graphed it in an interesting and useful way. But the negative feedback where relatively less Sept sea ice extent leads to stronger rebound in the following March and relatively more Sept ice extent leads to a weaker rebound, was not widely known, despite being in plain sight. Most people are busy looking at trends rather than making sense of the noise in the data.
Here is an earlier reference, there are no other mentions of a negative feedback in the comments:
https://judithcurry.com/2015/10/04/why-is-the-arctic-climate-and-ice-cover-so-variable/#comment-735042
Captain obvious reminds me that maximum extent of sea ice is limited when the ice reach the land, which it does in arctic pretty much everywhere except between Greenland and Norway.
So, while it may appear a surprise that the refreezing is more or less equal to the previous melting, it actually is not.
That’s why we focus on the minimal extent, not the maximal
Melting season summary:
http://neven1.typepad.com/blog/2017/09/excellent-melting-season-summary.html
Highlights:
“The decline of Arctic ice didn’t set a record this year, with sea ice extent coming in eigth after record-setting 2012. On September 13, at the summer minimum, sea ice covered 4.64 million square kilometers; that’s 1.25 million square kilometers more than 2012.
However, that fact was overshadowed by another: experts say what matters most in the Arctic is the total volume of ice — a combination of thickness and extent. 2017 saw summer volumes among the lowest ever recorded.
The Arctic set still another record that concerns scientists: no other 12-month period (September 2016 to August 2017) has had such persistently low sea ice extent.
The Arctic ice is therefore showing no signs of recovery, scientists say, and its decline is likely continuing to impact the Earth’s weather in unpredictable and destabilizing ways.”
griff says
The Arctic set still another record that concerns scientists: no other 12-month period (September 2016 to August 2017) has had such persistently low sea ice extent.
The Arctic ice is therefore showing no signs of recovery, scientists say, and its decline is likely continuing to impact the Earth’s weather in unpredictable and destabilizing ways
henry says
no need to worry.
the amount of energy coming in is governed by the various SC’s one of which is the 1000 year Eddy cycle. There is indeed historical evidence that the Vikings colonized Greenland in areas that were only uncovered from snow and ice recently. These Nordic rumors of a NW passage at the beginning of the last millennium were indeed so persistent that the Dutchman Willem Barentz in the 16th century got a ship and crew to ‘find’ it. Unfortunately, as we know, he got stuck and he and his crew all lost their lives. That is why they now call it the Barentz Sea.
So, where we are now, is exactly where we have been before, a 1000 years or so ago. There is no denying to it, as the records will show.
That there is no man made global warming can be proven from simple observations.
Willem Barentsz was looking for a NE passage. His ship became entrapped in the ice near Novaya Zemlya where the crew stayed almost a year. Willem Barentsz died on 20 June 1597 on the return voyage. 12 of the original 16-men crew reached Amsterdam in November that year.
You tell me. The NE I can believe if I look at directions but I thought they all froze to death on NZembla. Have to check that. It does not change my narrative. Willem was convinced that a passage existed to the other side of earth which he must have surmised from nordic myths or stories being passed on from generation to generation. Javier knows all about the 1000 year Eddy cycle.
Well, since scientists have been consistently wrong on the Arctic, we will just extrapolate that and assume they are still wrong.
Volume never mattered when extent was decreasing, and volume is the output of a computer model. It is to be trusted as much as CMIP5 models that are unable to reproduce temperature.
Javier October 6, 2017 at 10:54 am
“Well, since scientists have been consistently wrong on the Arctic, we will just extrapolate that and assume they are still wrong.”
The same goes for Griff.
Bet on it Griff or go shut up.
“saw summer volumes among the lowest ever recorded.”
Again with the abject ignorance of anything to do with Arctic sea ice.
You are talking about an insignificantly short period of RECOVERY from the highest extents in 10,000 years
The current levels are FAR above what they were for 90-95% of the last 10,000 years.
So stop you monotonous chicken-little sea-ice bed-wetting, and face facts for a change.
Eight of Griff was trying to tell us it was going to be 3rd lowest 2 weeks before.
Griff,
Arctic sea ice has been growing since 2012. No amount of gibberish can change that fact.
Antarctic sea ice is still growing here in mid-October. Yesterday it took out its September high.
Javier – can you comment on the trend of advancing date of ice maximum and minimum over the last few years? Did it continue this September? This (unsustainable) trend is presumably leading to some kind of regime/state change.
Hi Ptolemy2
Yes, the melt season ended on the 13th of September, with only one year, 2016, ending earlier for the past 11 years.
In my opinion the trend is a reflection of cooler summers in the Arctic. According to NSIDC:
“Looking back at this past summer (June through August), air temperatures at the 925 hPa level averaged for June through August were near or below the 1981 to 2010 average over much of the Arctic Ocean, notably along the Siberian side centered over the Laptev Sea (1 degree Celsius or 1.8 degrees Fahrenheit below the 1981 to 2010 average).
Like 2016, the summer of 2017 was characterized by persistently stormy patterns over the central Arctic Ocean, reflected in the summer average sea level pressure field (Figure 2b) as an area of low pressure centered just south of the North Pole in the Siberian sector of the Arctic. As has been shown in past studies, low pressure systems found over the central Arctic Ocean in summer are typically “cold cored.” This helps to explain the cool summer temperatures noted above.”
http://nsidc.org/arcticseaicenews/files/2017/10/PressAnomSL_JJA2017-350×321.png
Cooler summers and warmer winters. The alarmists just can’t seem to get it through their heads that the heat to melt that ice has to come in the summers and not the winters. Right now about the whole of the warming anomalies are at the poles.
Antarctic sea ice is still growing. Maybe it will take out the Sept high after all. In 2015, its high came in Oct rather than Sept.
Sea Ice Extent Sinks to Record Lows at Both Poles
Arctic sea ice appears to have reached on March 7 a record low wintertime maximum extent, according to scientists at NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. And on the opposite side of the planet, on March 3 sea ice around Antarctica hit its lowest extent ever recorded by satellites at the end of summer in the Southern Hemisphere, a surprising turn of events after decades of moderate sea ice expansion.
https://www.nasa.gov/feature/goddard/2017/sea-ice-extent-sinks-to-record-lows-at-both-poles
It’s fine. Like I told griff.
You still don’t get it Jack. The decline of the last TEN years is about ZERO!
http://www.natice.noaa.gov/ims/images/sea_ice_only_small.jpg
You need to see the cyclic behavior to realize they go up and down over the decades.
Jack,
You are mistaken. Arctic sea ice did make a very slightly new low in March, due to a weather event. But Antarctic sea ice did not set a new low. At least 1986 was lower. And, as I noted, it is still growing and liable to take out the September high today or tomorrow. Fairly unusual for it still to be growing this late in Oct.
The reason Antarctic sea ice was low this year was because of a combo of freak weather events late last year, in the austral spring.
Sorry, but sea ice globally is on the rebound. Antarctic grew from 1979 to 2014, then backed off due to the Super El Nino, followed by the aforementioned late 2016 events. Arctic sea ice has been growing since 2012 and has been flat for a decade. The past five years averaged higher than the previous such interval, despite the effects of the El Nino.
Reality shows you wrong.
Yup. It grew enough yesterday to take out the September high.
We have some extreme cold here in South Africa.
Even snow at some places…
It has lately been chilly in Chile, too.
Chilly in Chile? Sounds funny. You r from Chile?
Henry,
No, but I know people who live there and send me messages in the bizarre Spanish dialect spoken there.
Javier: “Around 1998 Arctic sea ice changed its dynamics and entered a period of higher volatility. One possibility is that below a certain size the Arctic sea ice sheet becomes more unstable and sensitive to weather phenomena.”
WR: Oceans might have played the main role in the change of the dynamics in the second half of the nineties. Huge subsurface (!) warm water pulses were entering the Arctic in the mid-nineties and 2000’s, enough to melt all the Arctic ice several times.
For more information about warm water pulses and their effects:
Arctic Ocean Warming Contributes to Reduced Polar Ice Cap
http://journals.ametsoc.org/doi/abs/10.1175/2010JPO4339.1
Abstract
Analysis of modern and historical observations demonstrates that the temperature of the intermediate-depth (150–900 m) Atlantic water (AW) of the Arctic Ocean has increased in recent decades. The AW warming has been uneven in time; a local ∼1°C maximum was observed in the mid-1990s, followed by an intervening minimum and an additional warming that culminated in 2007 with temperatures higher than in the 1990s by 0.24°C.
Fate of Early 2000s Arctic Warm Water Pulse
http://journals.ametsoc.org/doi/pdf/10.1175/2010BAMS2921.1
The water mass structure of the Arctic Ocean is remarkable, for its intermediate (depth range ~150–900 m) layer is filled with warm (temperature >0°C) and salty water of Atlantic origin (usually called the Atlantic Water, AW). This water is carried into and through the Arctic Ocean by the pan-Arctic boundary current, which moves cyclonically along the basins’ margins (Fig. 1). This system provides the largest input of water, heat, and salt into the Arctic Ocean; the total quantity of heat is substantial, enough to melt the Arctic sea ice cover several times over.
http://science.sciencemag.org/content/356/6335/285
Greater role for Atlantic inflows on sea-ice loss in the Eurasian Basin of the Arctic Ocean
Abstract: Arctic sea-ice loss is a leading indicator of climate change and can be attributed, in large part, to atmospheric forcing. Here, we show that recent ice reductions, weakening of the halocline, and shoaling of the intermediate-depth Atlantic Water layer in the eastern Eurasian Basin have increased winter ventilation in the ocean interior, making this region structurally similar to that of the western Eurasian Basin. The associated enhanced release of oceanic heat has reduced winter sea-ice formation at a rate now comparable to losses from atmospheric thermodynamic forcing, thus explaining the recent reduction in sea-ice cover in the eastern Eurasian Basin. This encroaching “atlantification” of the Eurasian Basin represents an essential step toward a new Arctic climate state, with a substantially greater role for Atlantic inflows.
Antarctic sea ice still growing. It’s tracking 2002 closely, so should turn down shortly.
A few more days, at most.
I think it is cooler than usual here (sh)