More sea ice and more methane

Arctic Methane Emergency Group? refers. Via GP I find this discussion on a “geoengineering” newsgroup (gosh how quaint – people still use newsgroups? Maybe retro is back). AJL finds my article “damming” but Ken C finds it “a little distasteful”. But both are worried, quite rightly, about credibility if the AMEG’s wilder claims (and people) aren’t challenged.

Ken C points to September Arctic sea ice predicted to disappear near 2oC global warming above present (JGR, doi:10.1029/2011JD016709) which is interesting, because that is very non-catastrophic and very non-nearterm: 2 oC puts it at ~2070 or something, depending on your scenario.

A recalibration of an ensemble of global climate models using observations over 28 years provides a scenario independent relationship and yields about 2oC change in annual mean global surface temperature above present as the most likely global temperature threshold for September sea ice to disappear, but with substantial associated uncertainty.

chart

Which brings me on to Now, and Cryosphere Today has a nice interactive chart, which I’ve inlined above (see-also). This year – yellow – seems quite wobbly; from bumping along the bottom it is now well up in the middle of the pack. But that is midwinter; there is still all to play for in the year ahead.

ccgg.BRW.ch4.1.none.discrete.all Switching very briefly to methane (the AMEG people were a bit annoyed their nice discussion had got hijacked by sea ice), the pic here shows… nothing very exciting. And it is Barrow, not global, per special request of Eli. This provides some kind of constraint on the hugeosity of whatever methane release is occurring in the Arctic.

And so, in the end, back to the Dark Side, where Watts had some story about sea ice. I ignored the bit about the Skate – if you’re interested, Eli has the story on that, and the other half too. But the bit about IPCC ’90 using pre-1978 sea ice was more interesting. Its true, they did (though it was a surprise to me). Presumably because back in 1990 the SSMI/R record was rather short, and it wasn’t obviously silly to use other stuff (for the full story, and exactly what other stuff, read RMG who knows). Anyway, I guessed wrong: it wasn’t ESMR (couldn’t have been, as RMG points out, because there would have been gaps). But what is fun, if you’re a detatched spectator, is how the Watties once again jump onto the good old conspiracy theories of how things were pure then but the global conspiracy has subsequently conspired to wipe out any memory of our giant reptilian overlords whatever. This is definitely a case where you don’t need fancy explanations for their errors. There is a constant stream of junk, no time to think or evaluate, and no need anyway – its all denialotainment, nothing real, and like the headline in the Daily Mail will be conveniently forgotten very soon.

Oh, and don’t mention Scafetta.

Refs

* Anthony Watts Misleading His Readers About Surface Temperature Record – it might be convenient to put this where I might find it again
* How reversible is sea ice loss? J. K. Ridley, J. A. Lowe, and H. T. Hewitt

Sea ice pic

I used to like the IJIS sea ice pic for comparing this year’s progress. And them AMSR went down (I hope I’ve got that right, I really wasn’t paying attention) and they stopped updating. But C points me to

which, while not so pretty, is a good substitute. That comes from http://gfspl.rootnode.net/index.php/arcticiceart which has others.

This post was mostly for me to link to the pic for my own convenience. But we could also look at it… too early to tell, but we seem to be bumping along at the bottom of the range at the moment. Time will tell.

Those teabaggers; etc.

Misc stuff. I think I’ll press “publish” now to distract you. Oh look, there’s a badger…

Early Warning with some interesting speculation and pointers re the possible US default. The “only someone batshit crazy would do that; oh f*ck, these teabaggers *are* batshit crazy” is fun. But I like the idea that even a brief default – assuming they came to their senses and caved afterwards – would add some tiny amount to US interest rates forever after. Are they really that crazy? Or will the big money have a quiet word in the right ears?

Timmy again, this time pointing out (well, it was the point of interest to me, you might care for the wider point) just how mind-bogglingly tiny the tradeable economies of some countries are. A graph of this would be nice, I think.

Mr. Gore Finds the Link by mt and (just to provoke) Mencken on crowdsourcing by a man of many names.

Eli has a new idea for betting on sea ice (which I see is looking better just now).

Newspapers follow bias not cause it – not quite true but fairly true. Certainly, an unwelcome idea all too rarely considered. Just as a people gets the politicians they deserve, they also get the press they deserve. Not me, of course, because I get none of them; but you plebs, yes.

Refs

Pic added per comments; see-also here

Sea ice, part 2

Or perhaps part 3. I’ve lost track. Sea ice – and now for something just a tiny bit different refers, as does the earlier This year’s sea ice. Yes, it looks like being part 3.

AMSRE_Sea_Ice_Extent-20110504

The above is the IJIS sea ice. Nothing very exciting at the moment (NSIDC have some nice pix. April 2011 was bang-on trend). As you recall, we’re trying to agree a bet or bets. I want to bet on monthly extent and some of the others want daily. After too much equivocation, I’ve decided to stick to my guns: monthly it is, and if you don’t like that, you’ll need to find someone else to bet with. Or, you can apply a handy adjustment. Rob reckons (based on IJIS) that the difference between monthly and daily is 0.17 (see this comment so you can adjust your expectation based on that, if you like.

Here is the pic I’m basing stuff on:

sea-ice-again

Green line is trend-to-year-using-all-data; so the 2011 point is the first extrapolated, and so on. Blue-dash is the trend, using last-10-years. And purple-dash is the same, but excluding 2007 (on the 2007-was-weird-theory; I’m not actually using that line). Red is the LS/Crandles exponential fit. What I find interesting is that every year since 1997 (except 2001) has been below the long-term trend “prediction” for that year. So I’m coming round to the view that things have changed. That means that for the pocket-money type bets, I don’t mind sticking to my pet theory (green line, so to speak) but for the serious money I’m afraid I’ll shift to the last-10-years theory (blue-dash). Where is the line dividing pocket from serious money? I don’t know, but $100 is P and $10k is S.

So to re-visit some earlier stuff: I said the chance of something beating 2007 and setting a new record low within the next 3 years (including 2011) seems quite good. So I’m not betting on that in response to Neven’s offer. But if I switch to the not-so-safe green line I think that just about fits the error bounds, so I’m now happy to take that on for the proposed E50. I’m basing that on the monthly values, of course. If you want to take up the offer based on daily values, then OK as long as we have a “buffer”: if the daily and monthly disagree about whether there is a record or not, the bet is void. Covering “the next 3 years” ie 2011, 12 and 13.

Another multi-year bet was Peter Ellis who says Allowing myself a reasonably wide fluff margin, like you’re doing, I’m prepared to bet £50 that the September monthly average will go below 2 million some time between now and the end of 2016. Bet voided if there’s one or more Pinatubo-scale eruptions between now and then. That looks OK; accepted.

Crandles offers 3 separate bets on the average of [2012, 2013 and 2014] (to be above/below 4.294, I take the high side), of [2013, 2014 and 2015] (4.119, ditto) and of [2014, 2015 and 2016] (3.94, ditto) for £67 each. That seems reasonable and is accepted.

That leaves me trying to satisfy Rob, which I think will be harder, since he wants to bet Real Money ($10k), so I’m going by the pale-blue-dashed-line. I think we might best off going for a bet on the single year where we disagree most, which (within an interesting timeframe) is probably 2016. So taking the 2016 point and subtracting my cowardly 0.5, I offer above/below 3.1, with me taking the high side. The data I’m using there is NSIDC (I’m fairly sure 🙂 monthly average extent. Having just checked, the IJIS seems to agree closely, as I’d expect (but I can’t find the monthly averages for that pre-made, so I checked 2007/09, which was within 0.1 of NSIDC). I suggest again that we buffer it: if the 2016 value for NSIDC or IJIS differs enough to affect the result, the bet could be void. To sweeten this not-very-good deal, I also offer Rob (but not me) the option to back out once the 2011 minimum data is in.

I think there are other people who have suggested they believe Maslowski’s “near total ice loss by 2016” stuff, and if you believe that, then I’d hope you’ll be happy with 3.1.

Did I forget anyone?

Sea ice – and now for something just a tiny bit different

[Update: see comments. We’re having some dispute about whether to bet on the monthly averages (the scientifically respectable thing to do) or daily min (the wildly exciting popular choice). I need to bother work out the numbers. Until then, you’ll have to be patient (2011/3/31; I’ve adjusted the posting date from 2011-03-22 to push this to the head of the queue)]

But not very different. Neven reminds me, again, that I promised to put up a slightly longer-term bet; see This year’s sea ice and in particular this comment and reply.

Neven offers:

I’d be willing to bet 50 euros on a record low within the next three melting seasons. And with record low I mean absolute daily minimum extent based on data as reported by IJIS.

Well, we need not worry about the amount for the moment, instead I’m trying to set the terms of the bet (for amounts, it will be word-of-honour for anything down at the “trivial” end and something a little more formal if you want to go above £1,000).

I dislike daily values; monthly means are better, and are less likely to be influenced by oddities, and more likely to be consistent between series. I’m happy to use IJIS though.

Otherwhere, Gareth predicts the end of summer sea ice in 5 years, based on extrapolating thickness trends, and I’ve taken the liberty of ripping off his image. This I don’t believe at all, and if anyone is prepared to bet on no (or essentially no) summer ice by 2016, I’ll be very interested.

Anyway, here is the pic I’m basing my judgement on:

seaice-again

(this is a mod of one from a previous post). Black line is just the obs. Green line is trendline using all the data that far (so it is a straight line into the future). The other lines are a bit more complicated, and I keep forgetting what they are: the blue line is the trend, using data only as far as the point on the x-axis, but taking the trend to where it would be in 2010. The red line is the same as the blue, but using only the 10 years before that point. And lastly the one that matters is the purple line, which is the trend to 2013, again using the previous 10 years, though displaced off (so the point at 2013 is drawn from 2001-2010 data; the point at 2012 from 2000-2009, etc).

Using last-10-years is being pessimistic (or from my point of view, erring on the safe side) but based on that, the chance of something beating 2007 and setting a new record low within the next 3 years (including 2011) seems quite good. So I’m not betting on that; after all, remember that what we’re aiming for is a bet that both sides regard as a sure-fire win for them :-). So, based on those lines, and needing the usual error margin of 0.5, which I’ll multiply by sqrt(3) since there are 3 years, I think a “fair” (ish) bet would be on the ice going below 3 (whatever the units are, I forget) any time during the next 3 years. Anyone interested, or care to dispute my numbers?

Days vs Months

[Added in update, 2011/3/24 22:00]

Clearly, people would rather be betting on a record *daily* low, whereas I’d rather think in terms of monthly averages. My justification for that is that it reduces the statistical noise, and so allows for smaller uncertainty margins. Though I admit I haven’t looked at the day/month differences. I suspect that really it shouldn’t matter too much: ice can’t vary much on a daily basis; it isn’t possible to have some vast down-spike on just one day (barring an unlikely compression event). Conversely, if you believe in a record daily low, then you ought to believe in a record monthly low, too.

Refs

* IJIS / JAXA ice extent which DA notes (prematurely, but probably correctly) has just peaked this year.

This year’s sea ice

Time for another look at sea ice. Here is the familiar IARC-JAXA plot:

jaxa-seaice-2011-02-27

And we see: well, it is looking low, and has been consistently all winter. Not record-breakingly, like it was last December, but even so. Interesting.

This year, I’m not planning to run a book, unless anyone offers to make a worthwhile bet. I’ll put up my “prediction”, which is the same as ever: the mean prediction is for the trend amount, i.e. the same as last year minus a little bit (5.235, as I recall), and the “bet range” is that plus or minus interannual variation, which as I recall is around 0.5 units. If you happen to believe that this year’s ice will be stonkingly low (or, indeed, high), then perhaps we have something to bet about.

C points out that Intrade is offering prices on 2011 being greater than 2007:


Price for Minimum Arctic ice extent for 2011 to be greater than 2007 at intrade.com

and hopefully that chart will make sense for a while. I think I should probably be buying at that price (42.5) since I think 2011 will be greater than 2007. And so, I did.

But the other seaice-y thing I was supposed to do was go back and rip to shreds Gareth’s prediction of an ice-free Arctic by 2016 (I know, he didn’t quite say that, but never mind, I’m eggagerating for effect). Tell yer what, I’ll quote him:

if the relationship between ice volume and extent evident in the NSIDC and PIOMAS data over the last 21 years continues in the near future, then the Arctic will be effectively ice-free in late summer sometime between 2015 and 2020

Now there area couple of problems with what Gareth has done. The first is (on taking a second look) rather striking: he hasn’t done the projection properly. He has taken the trend-line over the last, say, decade; but he has anchored that trend on the last value. Which is lower than the trend line. So he hasn’t projected the trend line itself forward, though he has (I assume) used the right slope. For volume, that makes a difference of about 2 units (by eye) which is worth about 5 years (on the 2001-2020 version). Similarly, the thickness will be strongly affected. However, I disagree by more than that.

Fundamentally, I think his projection of volume and thickness trends forwards, and using them to derive extent, is non-physical. Or perhaps, not using the best quantities. I think the extent (or, equivalently, the area) is more fundamental.

This is driven by my view of the sea ice as part of the energy balance of the Arctic. Ice free ocean (in winter) is going to freeze and make metre-thick ice. And if it survives the summer, it will thicken over time, until advected away and melted, or melted in place. And there is a certain “natural” area of winter ice. So unless something unusual and exciting happens during the spring and summer (as it did in 2007) the ice will follow its usual patterns. I’m not explaining myself very well, I can tell. Let me try just a little bit more: in winter, there is “excess cold” available: the ice freezes up, till it is ~1m thick, and then it doesn’t grow much more, because of the insulating effect (waves hands for effect). But in summer, melt is ~linear on the warmth available. So there is a sort of stabilising effect.

Of course, I may be wrong; this isn’t my field any more. And its not as if I’m betting the farm on this. But it is what I’m basing my “predictions” on, and why I still expect there to be summer ice n 2050.

I still need to fold this pic I drew last year:

seaice-plus-trends

into my analysis. That suggests that I am over predicting ice by ~0.4 units.

ps: via the Baron, I see that Curry is still pulling numbers out of her hat instead of doing science. But that is blog science for you: you can just make stuff up and no-one cares. When did Curry change from being a serious scientist into a comic turn?

pps: I’m finding Early Warning interesting reading nowadays. Lots of graphical analysis of oil prices,

Refs

* 2010 result