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 in 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

Forecasting

On of the key parts of science is prediction. Or so we’re told. So it is fun to watch various people rip Steve Goddard’s predictions of sea ice to shreds. WUWT is the one boosting Goddard’s worthless noise.

* RMG seems to be the most complete, prompted I think by:
* Tamino and
* Neven.

There’s a video, too, if you’re in the habit of watching moving pictures.

Update

An update, but worth its own header. While we’re on forecasting, I am reminded of something altogether more real: the Keenlyside fiasco. RC has a recent post pointing out how wrong K et al. were (but in a caring, consensual sort of way, because RC are obliged to be nice. I’m glad I’m not like that). Even more damaging to their credibility, K et al. are now in full stealth mode and refusing to discuss the “forecast”.

Refs

* Sea ice: and the winner is… no-one!
* Latif / Keenlyside / Cooling, revisited
* The climate bet is decided – or not – more weaselling by K et al.
* Losing time, not buying time – RC post relevant to the digression the comments ended up making

Sea ice: and the winner is… no-one!

Hurrah. That saves lots of effort paying :-). Not long ago it was looking bad for the good guys (i.e., me) with a “douple dip” recession of sea ice. But a strong perforcance from the boys up north in the mushy white stuff stakes saw a sharp rebound at the end of the month, leading to a monthly average for september of 4.90 (thanks for C for vigilance). As a reminder, recent years have been:

2000  9      Goddard      N   6.32   4.31
2001  9      Goddard      N   6.75   4.55
2002  9      Goddard      N   5.96   3.98
2003  9      Goddard      N   6.15   4.01
2004  9      Goddard      N   6.05   4.35
2005  9      Goddard      N   5.57   4.03
2006  9      Goddard      N   5.92   3.97
2007  9      Goddard      N   4.30   2.78
2008  9       PRELIM      N   4.68   2.93
2009  9      NRTSI-G      N   5.36   3.42
2010  9      NRTSI-G      N   4.90   3.02

Or so says ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Sep/N_09_area.txt. Other datasets will give you slightly different answers, of course. Note taht 2010 gets the coveted number 3 spot in terms of both September average and absolute minimum.

AMSRE_Sea_Ice_Extent-2010-10-02

The bet for this year was (from Three views of sea ice).

That the september mean ice *extent* be below 4.835; but with a “buffer” where we call it a draw: between 4.735 and 4.935, no one wins. I’m taking the “high” side of this; anyone interested in the “low” side let me know. For my part, 4.835 is arrived at as the 1979-2009 trend extrapolated, minus 0.5 which is the SD. It seems to have become tradiational for people to bet small amounts, which is fair enough if we’re just playing. But this was intended to flush out the “the sea ice is in catastrophic decline” people. OTOH, if there are any “the sea ice will certainly recover this year” people then you can get odds on trend-plus-SD, i.e. ice being above 5.835 if you like (note that those are all spuriously precise but never mind)]

So, if we’d played for just-the-number (without the buffer) I’d have won; but I agree, it is better to include the buffer. Assuming I (or ws it C?) did the calcs right, the trend line was for 5.335, and we’re clearly below that, but by less than the SD, so it doesn’t matter.

Refs

* Three views of sea ice – defn of this years contest.
* 2009
* 2008
* Lab Lemming’s pool (I think I’m the very broad green line)
* Tamino got lucky

Update: pressed by C in the comments, I’ve now calculated the trend for myself, and so I’ve added this pic:

seaice-plus-trends

which shows the extents, the trend-to-2010 calculated using all previous years, the trend-to-year using all previous years, and the trend-to-2010 only using 10 previous years. I make the baseline prediction for next year 5.235, which agrees with NB, so all is well.

Sea ice: throwing in the towel?

No, not me, DC, who says I’m thinking of paying up – 2010 looks more and more like 2006, not 2007. And indeed the latest Jaxa stuff looks like good news for the good guys (that is me, in case you hadn’t realised):

2010-07-17-AMSRE_Sea_Ice_Extent

And TS said:

Monckton is a blatant fraud who even lies about his own parliamentary status (or lack of status). Who cares what he has to say on some denialist blog? I would be interested to hear what you think is happening to the Arctic melt season. There was a lot of ghoulish pessimism a month ago, predictions of a huge melt this season and another record set for low had extent. What’s the real story on what’s happening, in your opinion?

Good question! Lets start off by getting rid of some disinformation, if I can, because really that is almost my only advantage. Look at the pic, and possibly at the hires version, and realise that there is almost no predictability of the September ice minimum from the early season activity. In particular, 2007 was totally unremarkable up until the beginning of July. Conversely, trying to predict from trends before July is very nearly worthless. Even now all I’d say is that there is no reason, from that pic, to expect anything very exciting from this year. C is looking for bids at intrade, where (2010 > 2009) is going for 45%. I’d still say it is 50-50 so that isn’t a very interesting offer. I’d take (2010 > 2007) like a shot, mind you.

That, of course, says very little about the various sat pix of actual ice concentration, and maybe the various ideas that the ice was looking a bit iffy. I don’t credit that much, either. Let me try to explain why. It depends on some modelling I did a while ago.

Impact of instantaneous sea ice removal in a coupled general circulation model (GRL, VOL. 34, L14502, 5 PP., 2007 doi:10.1029/2007GL030253 ) is a paper we did a few years ago, indeed one of the last things before I left science. David did most of it. We wanted to see how sensitive an ocean-atmosphere GCM was to initial conditions, specifically those to do with sea ice. So to begin with we did the simplest thing, which was to remove all the Arctic sea ice. We had planned to go on to do more sophisticated things, like take out 10 or 20% of the ice, but as it turned out even total removal of the ice made remarkably little difference, so we never did the more subtle tests. What happens is that the ice just grows back. It was at this point that I lost my belief in the “ah, but once the old ice goes away the new ice will crumble” stuff. Of course, this is a model not reality. And (slightly more subtlely) there is a wrinkle: of course when we remove the ice we’d left the sea “preconditioned” to grow more ice, because we didn’t touch the mixed layer state. So we tried again, this time warming the mixed layer to prevent sea ice reforming. And when we did that… well, still the ice grew back, but more slowly. So, absent evidence to the contrary, I don’t believe the “tipping point” stuff people talk about the Arctic ice.

Note that this says nothing about the long-term trend, which is of course downwards, as the world warms. But it does mean that my “prediction” for the year ahead is the long-term trendline plus a bound for noise (not forgetting to include “anomalous” years like 2007 and 2008 in the trend, because they are of course part of the natural variation, a mistake I made last year).