Wednesday, October 26, 2016

[jules' pics] BlueSkies, GreenTrees, YellowGrass

The BlueSkiesResearch is going awfully well.
NCAR - blue skies, green trees and yellow grass

Posted By Blogger to jules' pics at 10/26/2016 06:05:00 PM

Tuesday, October 18, 2016

Where in Google Map?

Think I've done this before a few times. The pic is perhaps a bit less obvious than it might have been, but still there are no prizes for guessing where we are (again), preparing to do a bit of Blue Skies Research:

The more important question, for which a prize is definitely appropriate is...where is our luggage? At Leeds Airport the sheep powering the treadmill had gone on strike so all computers were down and our baggage tags were written down by hand. That added to the delay on the flight down to Heathrow topped off with terminal change there left us not too surprised when nothing came off the carousel at Denver. Of course this had to be the one trip where we didn't get round to putting a bit of emergency clothing in our carry-on bags...but luckily our friend Rob managed to score some free Googlewear for us. One bag containing most of a bicycle has appeared so far (via a disgruntled courier hammering on our door at 4:30 am) but no signs of the other two bags with another bicycle and all our clothes...

Friday, September 30, 2016

[jules' pics] via Dent

Ever since we moved to Settle 2 years ago we have been meaning to cycle to somewhere, via Dent. Last time we visited Dent by bicycle was probably the mid 1990s, and all I really remember is a heron flying alongside us down the narrow valley in the cloud and rain. These days we like to think we don't have to do the ride in the rain, which is probably why it has taken to long to get around to it. Here's the trace on Strava.

First Ribblesdale to Ribblehead viaduct.
Ribblehead Viaduct

Then up and down to Dent viaduct.
Dent Viaduct

All the tea shops shut in Dent so brushed the dust off our feet and carried on to Kirkby Lonsdale via Barbondale

After a delicious luncheon, back to Settle via nowhere in particular.

Posted By Blogger to jules' pics at 9/30/2016 03:06:00 PM

[jules' pics] Via Berkshire

Uncle In Law expects to see pictures of our recent visit down south. Problem is I was really in transit from the Holiday Inn Express at Munich Airport where I'd attended an exciting and somewhat sleepless (aeroplanes are noisy!) meeting so wasn't really concentrating on picture taking.

The inside of one of the many churches in Wallingford was atmospheric.
Wallingford church

But apart from that all I really have are some portraits of the locals

Berkshire Show Llama

Berkshire Show cow

Posted By Blogger to jules' pics at 9/30/2016 02:53:00 PM

Monday, September 26, 2016


Could be painful... This has been updated!

Maybe not important enough for a skin graft ... yet ... but one can't help but look forward with some trepidation as to how pre-150ka may change!

ice-age tattoo

Lisiecki, L. E., and M. E. Raymo (2005), A Pliocene-Pleistocene stack of 57 globally distributed benthic d18O records, Paleoceanography, 20, PA1003, doi:10.1029/2004PA001071.
 Lisiecki, L. E., and J. V. Stern (2016), Regional and global benthic δ18O stacks for the last glacial cycle, Paleoceanography, 31, doi:10.1002/2016PA003002. 

Sunday, September 25, 2016

[jules' pics] Three Peaks Cyclocross

The Three Peaks Cyclocross - the bizarre sport of riding an unsuitable bicycle in an unsuitable place in unsuitable conditions - was this morning. James and I (and two other members of the Settle Wheelers) were marshalling at "Little Ingleborough", an important junction in the paths, at 630m. It wasn't cold. At least not until one had been stood in the howling wind on "Little Ingleborough" for an hour. We must have had it easier than some of the other marshals however, as Ingleborough is the first peak of the three so the field would be much more spread out later on. There were about 550 competitors with finish times ranging from 2h 58m to 6h 24m. 31 retired, mostly because their unsuitable bicycles were not suitable for the unsuitable conditions. At our relatively early stage in the race, we saw just one with what looked like a broken collar bone although a quite a few others that were still riding were bleeding from their shins.

The first two through finished the other way round. Not sure what happened as Rob Jebb was more than 2 minutes in the lead at this stage.
Rob Jebb

Paul Oldham



239 - that's a Settle Harrier (i.e. member of the Settle fell running club), Paul Lambert. Finished 122nd in 3h 56m.







606 - Joanne Jebb finished 502nd in 5h31mins

Posted By Blogger to jules' pics at 9/25/2016 06:09:00 PM

Wednesday, September 14, 2016 Fame at last

This is…..big:

And impeccably sourced🙂

It’s not beyond criticism, actually – the timeline doesn’t resolve possible rapid changes in temperature, so the comparison of smoothed paleo reconstruction with modern observations could be considered a bit misleading (see tweets here for example). But this is a relatively minor quibble on what is really a very nice graphical representation.
earth_temperature_timeline Assessing Paleoclimate Uncertainty

This was the title of a recent workshop held by the Past Earth Network (PEN) in Cambridge. PEN is one of 4 EPSRC-funded networks aiming to bring together mathematicians/statisticians and environmental scientists to help address problems in environmental change. While I wasn’t part of the PEN bid, I am acting as one of the co-leaders of one of the working groups (primarily interested in translating paleoclimate research to forecasting climate change).

The workshop was organised by another two of the working groups but they were kind enough to invite me as one of the speakers. But before it kicked off on Wednesday morning, I had the chance to go for a row on Tuesday night as a sub in William’s boat, which was fun. Haven’t done a whole lot of rowing in the past 20 years but it’s apparently not something you forget too easily, at least not after doing it in my sleep at 7am for several years…


The sessions were arranged with two speakers (nominally one climate scientist and one statistician) talking around a specific theme, such as parameter estimation/model tuning, spatio-temporal modelling, and time series analysis/tipping points. Some of these worked particularly well when both speakers were able to approach the same topic from different angles. There was quite a lot of overlap in scope between sessions with similar issues coming up in discussion throughout the meeting. For example, almost everyone was doing some sort of model-data comparison or synthesis, and it’s not always easy to decide how to do this. The first session on parameter estimation and uncertainty quantification was particularly good – it highlighted some practical and theoretical considerations that weren’t immediately obvious and which could materially affect research outputs.

The session I was talking in was about data assimilation, which is of course very much focussed on methods for model-data synthesis. Perhaps a limitation from the statistics point of view is that it tends to take a very model-centric view of the world, in that we are fundamentally trying to construct a model-like state that resembles reality (born out of its basis in model initialisation and weather forecasting), rather than just using models as one tool in reconstructing reality. Some state of the art particle filtering ideas discussed by the other speaker are likely to be useful to me, so I found that a particularly interesting part.

Cambridge was in the middle of a heatwave so it wasn’t ideal weather for sitting in a lecture room but as well as the rowing we had an afternoon of punting so it wasn’t all work and no play.

Corpus Christi, where we didn’t stay, looking resplendent in the sunshine.

Monday, September 05, 2016 International Conference on Paleoceanography, ICP12, Utrecht

One of the rules of BlueSkiesResearch is that we do not go to conferences unless our expenses are paid. Rules are made to be broken of course, but it is quite a good test for whether the organisers of a meeting really want us, which in turn indicates how valuable to us the meeting might be. So, when I got invited to speak at something called ICP12 in Utrecht, and they didn’t seem that keen to fund me, I thought I would not attend. Then I asked some paleoclimate friends whether it was likely to be worth going to, they replied that ItIsTheBestPaleooceanographicConference And ItIsVeryPrestigiousOnceInALifetimeOpportunityToBeAskedToTalk!!!! How curious. I wondered whether there were any other Paleoceaographic Conferences, and how being invited to the one and only could possibly be prestigious. Then ICP kindly offered to waive the enormous conference fee, and when I looked up flights I was surprised to discover that Bradford to Amsterdam costs tuppence, and takes 5 minutes. So I decided to go.
An Utrechtion icon

I flew in on Sunday lunchtime and sat in on an DeepMIP meeting about putting together the ocean data for the Eocene. The meeting was held un University buildings near the famous tower pictured above. I’m interested in DeepMIP indirectly, as a potential user of the results in terms of data-model comparison and Past to Future studies, and I’m also editing their paper in GMD. So that was quite fun, even though sitting staring at a screen covered in wiggles in a hot room on a sunny Sunday afternoon is not at all consistent with the relaxed attitude to work of this dedicated no-career scientist.

693 cups of coffee?

The ICP conference ran Monday to Friday with 5 half-hour talks in the morning, plus a poster session and a ‘perspective’ talk in the afternoon, with Wednesday afternoon free. My talk was first thing on Tuesday. I’d thought that I would be able to study the style of the talks on Monday and possibly tweak my talk a little if required, however I soon abandoned this idea and realised I would just have to go with what I had. People seemed to be presenting overview talks of an area peppered with a little of their own work, where as I had prepared something about my own research. It was all very interesting and well presented (talks in the first morning ranging from little bugs in sediment cores, to mantle dynamics and ice sheet modelling), and you never know when things may turn out to be important, but of course there was nothing directly relevant to my present research interests. The style of the questions was more like that I’ve seen in social science conferences than in climate, ‘obligatory opening, “Great Talk.” followed by…Extended wibble about how great I am… then…Half a question…’ I was glad to see that the women didn’t take any part in this tomfoolery.

On the topic of women, there was a weird demographic, with very few women my age or older and possibly a majority of women in the younger generations. It had the effect of making me feel a bit old! I look forward to the community being normalised with a 50/50 ratio at all ages over the next couple of decades.

In the afternoon I entered the poster hall and was amazed by the number of posters, some of which were quite good. For example, there was a much higher density of interesting things than at your average AGU session. I noticed that two had my name on them somewhere, and one even had a picture from one of our papers. This was quite encouraging, as it indicated that our research wasn’t quite so far removed from some of the attendees interests as the morning session had indicated. What I didn’t realise until 2 hours later when I was mentally exhausted from going round the whole lot, was that the posters would be up all week with just a few each day being defended by the authors. I’d wondered why the authors didn’t all seem to be in attendance. Oh well!


Beer with Britons

That evening I went out and drank beer with some Britons and then corrected some typos and omissions on my talk – with help from James over Skype. After another sleepless night at the noisiest hotel in Christendom (tinkling church bells every 15 minutes, all night partying, midnight brass band, and the ocassional silencer-less car or motorbike racing past), and a nice buffet breakfast, it was time for my talk on trying to make use of paleoclimate information to learn about future climate. Most of the speakers were staying at the hotel so we were able to chat over breakfast and it was surprising how nervous they all seemed, even days before their talks. And when I got to the conference hall, my co-speakers of the morning were quivering. Apparently there were about 650 in the audience, but I can’t see how that’s any more difficult than the 300 you can get in a large room at the EGU. I tried to fit in by working up some nerves, but didn’t really manage – I was just looking forward to it. The talk went mostly OK, and then I was delighted to receive some properly aggressive questions. No “great talk” platitudes for me, but straight in with, “I jolly well hope you haven’t done xyz, because that would be super WRONG!” Hurrah for climate modellers! Critical thinking is not dead!!

The rest of the morning, and indeed Wednesday morning carried on with similar diversity to the first morning, although the authors spoke much more about their own work, so I’m glad I didn’t redesign my talk at the last minute. Topics covered modelling, bugs and isotopes over a range of paleotime, but with quite a big emphasis around the Pliocene. The really nice thing about giving the talk was that from then onwards, instead of being ignored by 600 people, they all smiled at me when they saw me. Over the next couple of days quite a few people came up and asked me about my talk. Those questions and comments were the most directly useful part of the meeting for me.


Tuesday Touristing

Having done the posters on Monday, I took the poster session off on Tuesday and attempted to tour tiny Utrecht. But I kept getting lost. The conference dinner was on Tuesday evening and was good fun. The break on Wednesday afternoon provided the unfortunate opportunity to leave, which I took advantage of, as I’d have had to pay my own way for the rest of the week. Just as well really as I was exhausted from the noisy hotel and had pretty much done the breakfast buffet. But I was sad to miss the talks on Thursday and Friday so I hope they will be put online.

So, it was indeed a very good conference, and I am sure all the background information I saw will help inform my research, but I am still not sure why it is quite such a big deal. It would be nice to go again, but you only get invited once and I doubt the next location, which is Sydney Australia, will cost tuppence and take 5 minutes to get to.

Monday, August 22, 2016 On the meaning of independence in climate science

At long last jules and I have managed to submit the written version of a talk that I have given (bits of) no fewer than four times over the last few years (at NCAR, UKMO/HC, Schloss Ringberg and EGU). It had to get re-written several times and sit at the back of my mind on long bike rides and runs before it became acceptably coherent (to us, at least). I’m curious as to what people will think of it – it seemed to go down ok at the talks but sometimes it’s hard to tell…

The topic is "independence" as it pertains to both the understanding of ensembles such as CMIPn, and also to constraints on climate sensitivity. Our main point overall is that if you want to talk about independence in any context, you really need to present a mathematical/statistical formalisation that relates directly to the standard probabilistic definition: events A and B are independent iff P(A,B) = P(A)P(B). That is, the probability of both A and B is the probability of A multiplied by the probability of B. This generalises to conditional independence: events A and B are conditionally independent given S iff P(A,B|S) = P(A|S)P(B|S). A more practically useful (but mathematically equivalent) formulation is that events A and B are conditionally independent given S iff P(A|S) = P(A|B,S) – that is, if the conditional probability of A given both S and B is the same as the conditional probability of A given S. What this means in practice to an individual researcher is that, starting from their (probabilistic) prediction of A given knowledge of S, conditional independence of A and B rests on whether knowledge of B, in addition to knowing S, does or does not change their prediction of A. While this is no more than elementary probability theory, it seems to be an intuitively attractive way of addressing the question, eg in the case where A and B are observational constraints on the equilibrium climate sensitivity S. A point we also make in the paper is that these P()s are fundamentally subjective things just as much as a Bayesian prior is – there is no way of validating what observations should be seen in the case where S takes a value different from the real world, this counterfactual can only really exist in our heads and not in reality. In practice we often use models for this, which are themselves subjective creations, and in the paper we present an example to show how independence and non-independence of constraints can be investigated in the context of a toy model.

As for the question of model independence, the notation may be easier to interpret if we change the symbols and write something like P(M1|T) = P(M1|M2,T). This equation asserts that the models M1 and M2 are conditionally independent given the truth T. This is essentially the foundation of the truth-centred approach, and it would be great if true, but clearly many analyses of the models in CMIP ensembles have shown that it is not reasonable. An alternative conditional independence formulation, which we think is more relevant and interesting, is whether models are independent, conditional on the distribution of models. We illustrate how this does seem to encapsulate much of the discussion of model similarity, in that models from different research centres seem independent whereas pairs of models from the same research centres do not, according to a fairly straightforward analysis of model similarity.

It is quite possible – likely – that some others will be able to improve on how we’ve tried to define independence, but our point was really to argue that in principle we must use a mathematical foundation in order to make any meaningful progress – and also observe that mathematical definitions do exist which seem to match at least some real-world usage reasonably well.