Arctic life spiral

The decline of the Arctic sea ice is a perennial favourite among our millennarian friends, with "Death Spiral" being  favoured buzzwords used to keep the subject in the front of people's minds. Here's an example from shouty* (official) skeptic Phil Plait.

However, new light is thrown on the subject by a paper in Geophysical Research Letters (H/T Hockey Schtick) which finds strong covariability between sea ice levels and the Atlantic Multidecadal Oscillation. In other words a significant chunk of the variability seems to be entirely natural.

It's life, Jim, and just as we know it.

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*Is it just me, or is everyone involved in the Skeptics Society incapable of speaking without shouting?

Comments

[Martin A]

Er, what's the "Skeptics Society"?

Something to do with SkS perhaps?

[Billy Liar]

Who'd have thought that warm water melts ice?

[Chris Hope]

The paper itself gives you the answer: 'the AMO may be an important factor in the faster-than- projected decreases in sea ice, in qualitative agreement with a recent modeling–satellite-data analysis [Day et al., 2012] that attributes up to 5–30% to the satellite era (1979–2010) summer sea-ice decrease to the concurrent AMO warm phase.' (from section 5)

So it seems that 70 - 95% of the summer Arctic ice decline is not explained by this mechanism.

@cwhope

[Ed Hawkins]

Could you clarify what would see as a 'significant' chunk of the recent trend being due to variability?
cheers,
Ed.

[Phillip Bratby]

Warning, warning. "modeling" mentioned by a colleague of the infamous Peter Wadhams of ice-free-Arctic-by-yesterday predictions.

[Chris Hope]

Phillip: Just quoting what the paper says in case Andrew's readers didn't have time to look at it themselves. Sorry if you don't find that helpful.

@cwhope

[Green Sand]

For months the northern oceans have been anomalously warm.

Unisys

Earth Wind Map

This year's Arctic ice summer minimum should be interesting ?

[Foxgoose]

The paper itself gives you the answer: 'the AMO may be an important factor in the faster-than- projected decreases in sea ice, in qualitative agreement with a recent modeling–satellite-data analysis [Day et al., 2012] that attributes up to 5–30% to the satellite era (1979–2010) summer sea-ice decrease to the concurrent AMO warm phase.' (from section 5)

So it seems that 70 - 95% of the summer Arctic ice decline is not explained by this mechanism.

@cwhope

Aug 11, 2014 at 9:33 AM | Unregistered CommenterChris Hope

"The paper itself gives you the answer ……….. in qualitative agreement with recent modelling….that attributes up to 5-30%"

I'm sorry, Chris, but in any job I ever had where important decisions had to be made on the basis of technical data, an "answer" like this would have produced an immediate response of "can you get back to us when you have a clue".

I see that the Day et al (2012) paper covered data up to 2010. I don't have access to this paper - can you tell us what the data cut off was?. Presumably the unexpected 2013 rebound will have made a significant difference. How would it affect the comparison with the Day paper?

[Bishop Hill]

The problem with Day et al is that it is a modelling study, so the figure is only correct to the extent that the models are correct. Does anyone know if the model predictions are still running behind reality in the Arctic? Given the recovery in the last couple of years I wonder if the models have "caught up". (Also worth noting that the model understatement of sea ice decline was presumably partially due to the 2007 change in currents and the 2012 storm).

[Cheshirered]

Natural variation, you say? Impossible. That's plainly denier-speak. Accordingly you are booked in for a programme of re-education.

[Green Sand]

Bish, not sure if this helps:-

RSS - "Climate"

".......Over the past decade, we have been collaborating with Ben Santer at LLNL (along with numerous other investigators) to compare our tropospheric results with the predictions of climate models. Our results can be summarized as follows:

• Over the past 35 years, the troposphere has warmed significantly. The global average temperature has risen at an average rate of about 0.13 degrees Kelvin per decade (0.23 degrees F per decade).

• Climate models cannot explain this warming if human-caused increases in greenhouse gases are not included as input to the model simulation.

• The spatial pattern of warming is consistent with human-induced warming. See Santer et al 2008, 2009, 2011, and 2012 for more about the detection and attribution of human induced changes in atmospheric temperature using MSU/AMSU data.

But....

• The troposphere has not warmed as fast as almost all climate models predict.

To illustrate this last problem, we show several plots below. Each of these plots has a time series of TLT temperature anomalies using a reference period of 1979-2008. In each plot, the thick black line is the measured data from RSS V3.3 MSU/AMSU Temperatures. The yellow band shows the 5% to 95% envelope for the results of 33 CMIP-5 model simulations (19 different models, many with multiple realizations) that are intended to simulate Earth's Climate over the 20th Century. For the time period before 2005, the models were forced with historical values of greenhouse gases, volcanic aerosols, and solar output. After 2005, estimated projections of these forcings were used. If the models, as a whole, were doing an acceptable job of simulating the past, then the observations would mostly lie within the yellow band. For the first two plots (Fig. 1 and Fig 2), showing global averages and tropical averages, this is not the case. Only for the far northern latitudes, as shown in Fig. 3, are the observations within the range of model predictions........."

My bold

Scroll down to Fig 3

[Phillip Bratby]

to the extent that the models are correct

You have your answer right there. The unvalidated models are as correct as 2+2=5.

[Green Sand]

Sorry, somehow chopped this off the end:-

".......The reasons for the discrepancy between the predicted and observed warming rate are currently under investigation by a number of research groups. Possible reasons include increased oceanic circulation leading to increased subduction of heat into the ocean, higher than normal levels of stratospheric aerosols due to volcanoes during the past decade, incorrect ozone levels used as input to the models, lower than expected solar output during the last few years, or poorly modeled cloud feedback effects. It is possible (or even likely) that a combination of these candidate causes is responsible. ....."

[H2O: the miracle molecule]

Could you clarify what would see as a 'significant' chunk of the recent trend being due to variability?
cheers,
Ed.

No-one knows Ed because climate science decided to prosecute CO2 rather than learning about natural variability

[Ian W]

Does academia no longer validate their output and react to that validation? Surely that is the essential step in the scientific process, does the forecast from the hypothesis match observation. Instead of mealy mouthed searches for explanations for why there was a "discrepancy between the predicted and observed warming rate" the report from the project should be 'the hypothesis was falsified by observations.".

This same approach should be taken everywhere. On homogenization of reporting stations, the validation would be remove a reporting station with a full record from the set, run the homogenization and see if the 'invented' observations match the actual, Do this for every reporting station in the set. Gross errors fail the homogenization process, all errors are used to create error bars for the process that show its (lack of) accuracy.

Validation testing is simple - why are climate 'scientists' given a pass on this standard step in real science?

[JamesG]

The reason why the Arctic is shrinking more than models predicted is simply because the models have never managed to predict anything correctly anywhere at any time, either individually or combined. A true scientist would worry more about why the Antarctic is doing the exact opposite of the predictions rather than guess how much of the Arctic warming might have been natural. It is the cooling that is they key to climate: Greenhouse gases cannot produce cooling so find the cooling mechanism and you may have isolated mother natures contribution.

[tetris]

Bish,

A friend of mine is the master of one Canada's major icebreakers, on his way to the Arctic as I write.

We chatted about the ice in the Arctic Basin of the past years over coffee before he left yesterday, and he confirms two things:

1] take away the outlier 2012 minimum -due to a massive Arctic hurricane which blew a lot of ice out of the Basin- and the picture is clear: the turning point was 2007, with more ice at the summer minimum than the year before every year since;

2] the clear increase in multi year ice. How do these good folks know that apart from the stunning colours displayed by multi year ice? The sound and shock it produces when the ice breaker hits it.

Yet another example of facts having the better of models any time. Strange, that...

[dougieh]

@CH

"So it seems that 70 - 95% of the summer Arctic ice decline is not explained by this mechanism."

Do you really think this explains anything of use (or seems to) ? does it not show you are still feeling your way to an understanding of what is going on ? (as foxgoose implies above)

ps - 5-30% means it could be 30%. which in my book is "a 'significant' chunk of the recent trend being due to variability"

[Will Nitschke]

"In other words a significant chunk of the variability seems to be entirely natural."

This has been well established in the literature for a very long time. I seem to recall (a long time ago) RC discussing this. Their argument was that while sea ice is highly variable on multi-decadal time scales, the recent melt patterns are 'unprecedented' and this is due to an AGW component. I couldn't admittedly work out how they had researched such a conclusion, beyond their speculations...

I've also found it curious that so many have gone on record predicting that the north pole would be ice free in summer any year now. It takes a temperature rise of 30C (difference between winter and summer) to melt about two thirds of the cap. I always found it hard to imagine how they expect a 'recent' global temperature rise (1980-1999) of 0.3C to melt the remaining third, even allowing for polar amplification.

[Mark T]

I change the channel when Dr. Shouty is on any of the Discovery Channel (or related) programs. I was already pointing out his flawed understanding of the physical world back when he was just an astronomer with a blog about bad science (badastronomy.com, before merging with universetoday.com). He was actually likeable, albeit a little arrogant, and rarely ventured beyond his comfort zone. He may be (have been?) a good astronomer, but his "expertise" has certainly never extended beyond that from what I have seen. Once his book got a nod from Discover Magazine, and BA merged with UT, the forum became a haven for leftist political groupthink which necessarily included AGW worship. Needless to say, his comfort zone then extended into nearly every nook and cranny imaginable.. He was famous ya know. Ya, but I stayed at a Holiday Inn.

Mark