Saturday, 17 March 2012

Mid March Miscellanea.

This is a filler post with a couple of items mainly because I'm too whacked to write much due to work pressures.



Firstly the UK Parliament has had some sessions recently that I think are a must-see for Arctic climate change nuts. I've not learned much new from the sessions, but it's good to see the sort of points being made here and on other blogs being aired before a select committee, as part of the series of sessions entitled "Protecting the Arctic".

Session on 21/9/12. Prof Peter Wadhams and Prof Tim Lenton, scientists working on the Arctic, join John Nissen of the Arctic Methane Emergency Group in providing evidence before the enquiry.

Session on 14/3/12. Prof Julia Slingo OBE, Chief Scientist at the UK Met Office, gives evidence during the first 20 minutes. I must admit I got bored by the evidence from Shell and Cairn Energy so didn't watch it.

There are other sessions, but these seemed to be the most noteworthy. For more search for "Protecting the Arctic" from January to the present date from the search page here.

In essence the four participents fall equally into two camps: Peter Wadhams and John Nissen being concerned about East Siberian Shelf methane and a rapid transition (within years) to a summer with very little sea-ice. Tim Lenton doesn't express a view as to when we will see an open Arctic Ocean (unless I missed it), however his opinion is in line with Julia Slingo on methane - chronic not catastrophic. I'm particularly impressed by how Julia Slingo's views concur with my own as stated earlier on this blog, we seem to have been reading the same papers. One area where I disagreed with what she said was the implied attribution of the Petoukhov/Semenov mechanism in the Winters of 2009/10 and 2010/11, with regards the former I still think Cohen's explnation fits best. I may end up disagreeing on the imminence of a seaonally sea-ice free Arctic, but I'm now waiting until the Spring PIOMAS results are in to see if I'm going to change my mind on that.

Secondly, and finally, I've read Dr Jennifer Francis and Dr Steve Vavrus's paper entitled "Evidence Linking Arctic Amplification to Extreme Weather in Mid-Latitudes." Abstract. It's well worth reading, clear and succinct. In a nutshell, to quote from the conclusion:

In summary, the observational analysis presented in this study provides evidence supporting two hypothesized mechanisms by which Arctic amplification – enhanced Arctic warming relative to that in mid-latitudes – may cause more persistent weather patterns in mid-latitudes that can lead to extreme weather.

One effect is a reduced poleward gradient in 1000-500 hPa thicknesses, which weakens the zonal upper-level flow. According to Rossby wave theory, a weaker flow slows the eastward wave progression and tends to follow a higher amplitude trajectory, resulting in slower moving circulation systems...

The second effect is a northward elongation of ridge peaks in 500 hPa waves, which amplifies the flow trajectory and further exacerbates the increased probability of slow-moving weather patterns...

Essentially it's the same material covered in the lecture by Dr Fancis that I covered back in January, link, see the last comments that page for requests for pre-print copy. So we're seeing a growing pattern of evidence linking the loss of Arctic sea-ice to changes in mid-lattitude weather. As Dr Francis puts it:

The question is not whether sea-ice loss is affecting large-scale atmospheric circulation, it's 'how can it not?'

16 comments:

arcticio said...

Nice links, started to enjoy your miscellanea.

Unknown said...

Arcticio, Thanks, I'm continuing to enjoy your site. :)

arcticio said...

Julia Slingo was not that precise on volume and also did not stress the fact it might be worth to investigate to avoid surprises. But I like her point of view on geo-engineering.

Unknown said...

I think volume is a key metric to look for what the I suspect public understands as tipping points - massive shifts. The scientific understanding is not just a massive shift - but one that is harder to reverse than to initiate, i.e. hysteresis is involved.

One (or two?) of the papers I've read in the last year on Arctic tipping points find volume drops. The volume drop is associated in some models with a 'bifurcation' in the transition from seasonally sea-ice free state to year round ice free. A bifurcation being a tipping point with hysteresis.

I agree watching volume changes is crucial for spotting tipping points, with or without hysteresis. A precipitous volume loss may be the precursor to a precipitous extent/area loss.

I'm waiting for this Spring's PIOMAS because I suspect it may be telling us that we've hit a tipping point. As with area/extent - I see 2007 as being a weather driven event that occurred due to the previous thinning of the ice. However the extent of perenial sea ice has already undergone a 'tipping point' (rapid transition) as shown by Nghiem.

I liked Tim Lenton's view on geoengineering - we need to deal with the cause, and it's better to go for low hanging fruit like black carbon. At least I think I remember Lenton saying that - maybe it was Slingo. :(

My view on geo-engineering - I knew an old lady who swallowed a fly...
http://home1.gte.net/adgray/SONGBOOK/iknewa.htm

Geoff Beacon said...

I watched videos of the Environmental Audit Committee session when they took evidence from Tim Lenton, Peter Wadhams and John Nissen and the Julia Slingo session. I also attended a similar meeting of the All Party Climate Change Committee chaired by Lord Hunt, reported on the BBC website today: http://www.bbc.co.uk/news/science-environment-17400804

Neither the Environmental Audit sessions or the APPCCG meeting taught me any climate science I did not know already - your post on 6 February and following discussions were more informed. What these events did give me was an insight into is the state of play in UK climate science. Points that I understood:


1.Julia Slingo did not believe that the volume of sea ice is reducing at the rate that PIOMAS indicates.



2.Julia Slingo thought Arctic sea ice would not disappear in summer before 2025 to 2030. The better models were predicting 2040 to 2060.



3.Tim Lenton said "My best guess is sometime in the 2030s, maybe 2040s roughly, there will be an ice-free summer." (See transcript at http://www.publications.parliament.uk/pa/cm201012/cmselect/cmenvaud/c1739-ii/c173901.htm)



4.Peter Wadhams said "If you extrapolate the existing rate of retreat it might take 20 to 30 years for the ice to disappear in summer, but if you add in the effect of the thinning it is very much quicker, perhaps needing only 4 years."



5.John Nissen's estimate was even sooner: 2014 or 2015 or even this year.


What worries me is the criticism I have heard that modellers (Julia Slingo and Tim Lenton?) prefer to believe the models rather than the real world. Are their models of sea ice thickness underestimating the reality? Peter Wadhams goes to the Arctic to measure it.

On feedbacks in the models Tim Lenton said:

I personally would put quite a lot of clear blue ice-free water between my own position and John [Nissen]’s about how strong the feedback from the methane release is. It is not fair to say it is never really addressed. My colleagues down the road in the Hadley Centre in Exeter have permafrost in the latest state-of-the-art model being run at the moment for the next round of IPCC projections.

Last year John Mitchell told me:


We have started putting in our GCM the processes which would allow further feedbacks between methane and climate (we already represent some methane climate feedbacks through atmospheric chemistry)

The latest work includes some wetland processes and is currently being validated- this is still work in progress. We are also looking at permafrost but don't yet include processes that link with methane. As yet we don't include the shallow ocean methane processes.

That doesn't have quite the same sense as Tim Lenton's comment.

Geoff Beacon said...

I watched videos of the Environmental Audit Committee session when they took evidence from Tim Lenton, Peter Wadhams and John Nissen and the Julia Slingo session. I also attended a similar meeting of the All Party Climate Change Committee chaired by Lord Hunt, reported on the BBC website today: http://www.bbc.co.uk/news/science-environment-17400804

Neither the Environmental Audit sessions or the APPCCG meeting taught me any climate science I did not know already - your post on 6 February and following discussions were more informed. What these events did give me was an insight into is the state of play in UK climate science. Points that I understood:


1.Julia Slingo did not believe that the volume of sea ice is reducing at the rate that PIOMAS indicates.



2.Julia Slingo thought Arctic sea ice would not disappear in summer before 2025 to 2030. The better models were predicting 2040 to 2060.



3.Tim Lenton said "My best guess is sometime in the 2030s, maybe 2040s roughly, there will be an ice-free summer." (See transcript at http://www.publications.parliament.uk/pa/cm201012/cmselect/cmenvaud/c1739-ii/c173901.htm)



4.Peter Wadhams said "If you extrapolate the existing rate of retreat it might take 20 to 30 years for the ice to disappear in summer, but if you add in the effect of the thinning it is very much quicker, perhaps needing only 4 years."



5.John Nissen's estimate was even sooner: 2014 or 2015 or even this year.


What worries me is the criticism I have heard that modellers (Julia Slingo and Tim Lenton?) prefer to believe the models rather than the real world. Are their models of sea ice thickness underestimating the reality? Peter Wadhams goes to the Arctic to measure it.

On feedbacks in the models Tim Lenton said:

“I personally would put quite a lot of clear blue ice-free water between my own position and John [Nissen]’s about how strong the feedback from the methane release is. It is not fair to say it is never really addressed. My colleagues down the road in the Hadley Centre in Exeter have permafrost in the latest state-of-the-art model being run at the moment for the next round of IPCC projections.”

Last year John Mitchell told me:


“We have started putting in our GCM the processes which would allow further feedbacks between methane and climate (we already represent some methane climate feedbacks through atmospheric chemistry)”

“The latest work includes some wetland processes and is currently being validated- this is still work in progress. We are also looking at permafrost but don't yet include processes that link with methane. As yet we don't include the shallow ocean methane processes.”

That doesn't have quite the same sense as Tim Lenton's comment.

Unknown said...

Thanks Geoff,

Sorry about the problems you had posting - your comment ended up in spam for some reason.

For what it's worth I disagree with the 2030-2040 timeframe, I expect to see our first virtually sea-ice free (VSIF) minima next decade. Although as I say above I may be about to revise my estimate earlier.

I'm not sure the modellers prefer models to reality. The problem is we're all trying to work without enough on the ground (or ice) data. The models do show events like 2007 that don't lead to a rapid transition to a VSIF state. I disagree with Prof Slingo regards PIOMAS because the problem I can't get around is this - PIOMAS is well validated against the available observations of sea-ice thickness, so if its current massive volume loss is an artefact of the model then I can't figure out why (it was working before why not now), and as the drops of Spring 2010/11 are so large, why haven't the PIOMAS team put out some form of statement saying they doubt these results, they've had nearly a year since the last drop, nearly two since 2010.

I've been cautious of Wadhams after the Bryden THC results when IIRC Wadhams seemed to be convinced a THC shutdown was happening. However that doesn't mean Wadhams isn't correct now. Your point 4 puts Wadhams into the early VSIF state camp. Perhaps he's correct. The problem is I haven't found too much from Wadhams about sea ice thickness since 2007. There's a paper here from which you can see (fig 4) change from 2004 to 2007. Thats a drop in modal thickness from around 2.75 to 1.65 in the area studied. i.e. the sort of crash PIOMAS and ICESat imply. I'm preferring modal figure there because the change in the thickness distribution peak suggests the role of Nghiem's finding of massive loss of MY ice which is thicker. But this still leaves the question - what is happening now, since 2007?

With regards the models, I can't recall any papers examining thickness/volume changes in the projections of Arctic sea-ice. Most (all?) concentrate on extent.

Geoff Beacon said...

Thanks Chris

I spoke to one of the HOC Environmental Audit Committee on Monday who was leaning towards the view of Peter Wadhams (and PIOMAS ...) on the sea ice thickness.

Let's hope the Committee ask for the wider community of modellers to state their judgements clearly on ice thickness.

We need judgement now and "scientific certainty" when it's possible.

Unknown said...

Geoff,

I've been meaning to do a post on what models show based on a few papers I've previously read. Your comments above have provided the needed impetus. Now I just have to re-read those papers and read some more. Watch this space.

Geoff Beacon said...

Chris

This time I didn't get an answer to my recent letter to John Mitchell. In general I've found him helpful. Here's the letter. (I hope you can answer some of the questions.):


3rd March 2012

Dear John

Thank you very much for answering my questions in March 2011.

You may remember I was asking about the state of modelling with respect to climate feedbacks.
I mentioned a list of feedbacks from the NERC website.

1. reduced sea ice cover reflecting less of the sun's heat back out to space,
2. changing ocean circulation patterns
3. less carbon dioxide absorption by the oceans
4. increased soil respiration
5. more forest fires
6. melting permafrost
7. increased decomposition of wetlands

You kindly answered concerning the then state of the models with regard to methane emissions possibly because previously I had particularly discussed the role of methane with you. You said

We have started putting in our GCM the processes which would allow further feedbacks between methane and climate ( we already represent some methane climate feedbacks through atmospheric chemistry)

The latest work includes some wetland processes and is currently being validated- this is still work in progress. We are also looking at permafrost but don't yet include processes that link with methane. As yet we don't include the shallow ocean methane processes.

In the case of the melting permafrost (6) , I wasn't sure whether you meant that the CO2 emissions were in the models but methane emissions had not yet incorporated. Now I would like to ask what is the current state of GCMs with respect to all the feedbacks. Has there been progress and what is the “feedbacks position” with the GCMs to be used for AR5?

Which of the feedbacks mentioned above are now adequately covered? Perhaps item 6 should be disaggregated into

6a. CO2 from melting permafrost
6b. CH4 from melting permafrost

I am very grateful for your previous replies. I hope you find time for at least a short reply to these questions.

Unknown said...

Hi Geoff,

Sorry, but I really don't know enough to answer your questions properly as modelling implementation of the carbon cycle isn't something I've read much on. I have pondered trying to write something but it's a complex area and I don't want to cloud the issue with what would be little more than poorly informed speculation.

Geoff Beacon said...

Hi Chris

Thanks anyway but you may not need to know much to spot some of the problems with the current state of modelling - see below.

I hope you're OK with the mention of DOSBAT in my "Climate officials and climate provisionals"
http://www.brusselsblog.co.uk/climate-officials-and-climate-provisionals/

More importantly this is significant part of a letter my MP got from the Met Office on my behalf:

"Carbon dioxide and methane release from permafrost is an area of active research at the Met Office Hadley Centre. A simple framework has been developed for estimating the amount of carbon dioxide and methane release from permafrost. and to estimate the impact of this release on the global mean temperature. We expect this work to be published within the next 2 months. This is a step towards full representation or the permafrost climate feedback within the more complex Hadley Centre climate models – the outputs of which are used by the IPCC - which we plan to achieve within the next 2 years.

Currently, no work has been undertaken to incorporate methane release from ocean hydrates lnto Hadley Centre climate models.

I hope this helps."

Unknown said...

Hello again Geoff,

I'm on the verge of posting another long post - this one, as promised, about models and Arctic sea-ice.

I read your blog post, and saw your mention. Interesting post and I have no objection to your mentioning me.

I'll apply myself to your questions over the weekend when I'm somewhat more refreshed and have got this post published.

Geoff Beacon said...

Hi Chris,


John Mitchell of the Met Office's Hadley Centre has kindly replied to me. I had asked him about the treatment of various feedbacks in climate models. (I have added brackets to the numbering of my questions in lieu of the colour coding in his reply) He says


Hi Geoff

I apologise for not answering earlier - I now work part time.

Based on help from my colleagues

(1). reduced sea ice cover reflecting less of the sun's heat back out to space,

(2). changing ocean circulation patterns


1,2 are in most models and have been for years



(3). less carbon dioxide absorption by the oceans

(4). increased soil respiration


3,4 are in most carbon cycle models and fairly well established. There are a good number of such models in the current IPCC assessment


(5). more forest fires


5 we don't do yet, but could be important for changing ecosystems response to climate.



(6). melting permafrost

6a/b we don't have in the GCM, but have some simple modelling of. Too early to show any results yet, but we plan to publish later this year. Bottom line is that both CH4 and CO2 will be released as permafrost thaws. The magnitude is uncertain, but likely to be significant.



(7). increased decomposition of wetlands


7, we have in HadGEM2 but didn't enable as a fully coupled feedback, but we can diagnose changes in wetland extent and CH4 emissions


I would add that although these things may be important, they are not always easy to quantify, model, initialize and validate, especially 5-7. That is why is taking time ot implement them.

John

Unknown said...

Geoff Beacon,

I think I should at the outset state what my position is regards the models.

I treat model results with some caution. Whilst I am convinced that climate sensitivity (CS) is around 3degC, that's mainly because so many different approaches keep coming up with probability density functions peaking at around that temperature. I wouldn't waste my time arguing over whether it's 2.5 deg C or 4degC, but I am equally sceptical of claims of over 5degC or under 2degC.

This means I don't lose sleep over what temperature some model study says it will be in 2050, there are so many uncertainties that getting lost in the details is IMO futile. The qualitative picture is sufficient and robust - things will get hotter as we emit more CO2. However it does concern me that some activists who argue for a high CS don't seem to get a crucial fact - we don't need a high CS to get higher temperatures than the IPCC project. The IPCC are very conservative and in 2007 didn't really include carbon cycle feedbacks in projections (aside from warming of the oceans reducing CO2 solubility). So even with a CS of 3degC for a doubling of CO2 we could hit a doubling before some emissions scenario projects by virtue of carbon cycle feedbacks. In this respect I am far far more concerned about land permafrost than marine methane hydrates. I think there is a strong argument for land and marine hydrate emissions being chronic rather than catastrophic, and that the emissions from the East Siberian Shelf seem to be a longstanding issue - not a response to recent warming.

In all of your numbered points I'd really have to defer to John Mitchell (and colleagues) expertise. I started off blogging on the Arctic and that remains my speciality - even as an amateur one has to specialise. However I do have comments on two points.

Contd...

Unknown said...

contd...

Point 5. This could get very complicated and uncertain. There is the uncertainty over whether the Arctic region warms wet or dry, this is tied in with Francis's research into stuck patterns of the jetstream, what if we develop persistent highs over tundra in the summer - less cloud means more insolation and less rain, possibly ideal conditions for fires. Another issue surrounding whether the Arctic warms wet or dry is that wet warming will probably cause more methane from tundra, dry warming more CO2 (McGuire et al 2009). We're only beginning to see the start of the atmospheric impacts and there are already many surprises, who'd have thought that Siberian snow cover could cause the 2009/10 winter, or that low sea-ice in the Barents Sea could cause the recent January/February cold outbreak? What role are the atmopsheric changes playing in the advancement of sea-ice reduction beyond the model projections (see my most recent post).

Point 6, I've already made my views on that quite clear, however it seems to me that a lot more observational studies need to be done before this can be parameterised into models. To start we'd need to see more studies to answer the question of whether the methane emissions from the ESAS are due to current warming, or longstanding as a result of the early holocene inundation. Semiletov & Shakhova and colleagues are at the cutting edge of their area, it realy is early days for their research and it's important to take a measured view to avoid falling into the trap of misinterpretation as I mentioned earlier w.r.t. Bryden and the THC.

Add on top of all this the uncertainties inherent in emissions scenarios and the obvious problems regards models and the Arctic sea-ice and all I can see as being taken from the whole mess is a qualitative message - things are worse than the IPCC projections imply. I'm sorry to disappoint you but from my perspective we're running blind to a troubling extent. I don't mean to disparage the modellers here - there are a lot of seriously intelligent people working in that field, indeed being very smart is a pre-requisite in their profession. However I see a pace of change that is so fast it's hard for them to keep up, or perhaps it would be more accurate to say that it's hard for the groundwork, from which they parameterise, to keep up.

I suspect from our discussion that you want answers to the question of whether we're wandering into a catastrophe from a carbon cycle backlash. I can understand that you'd like to be able to answer the question either way, but I don't think there is an answer out there yet. People can chose to beleive John Nissen and the AMEG or to believe Dr David Archer and other scientists. I back Archer (chronic not catastrophic), although I've already outlined how bad chronic could be, but I could be wrong and AMEG right. In the end we just have to wait and see what happens - we'll know the answer when either the science falls strongly to one side or another or a catastrophe happens. Of course if people like Dr Archer (and by negligible implication myself) are correct and you're awaiting a catastrophe - you'll have a very long wait indeed. ;)

It's a crap answer but there it is.