WCRP OSC Day 4 and 5

Day 4 seemed to be pretty much IPCC day and suddenly there was a little bit more climate science. The plenaries (with Thomas Stocker chairing) kicked off with Susan Solomon talking about the near-irreversibility of climate change, based largely on the long lifetime of CO2 even if emissions drop to zero. While it's quite an intuitive and appealing analysis - the tail of the subsequent transient temperature rise to equilibrium is largely cancelled by the slow decline of CO2 - I can't help but think that the presumed barrier at zero emissions is somewhat artificial, as even reaching zero will probably require some carbon capture technology anyway (since some people will still use fossil fuels). Konrad Steffen then talked about ice sheet loss and sea level, and it seems likely that the IPCC will significantly upgrade its predictions for sea level from its "let's ignore ice sheets" position next time around. Then Peter Stott gave a nice overview of the successes and challenges of attributing weather events to anthropogenic forcing. After the previous night's excitement I didn't have much energy for the posters. The afternoon was all about understanding climate change, and had several interesting talks. Jonathan Gregory explored the approximations underpinning the standard linear forcing/feedback analysis and showed some useful applications and limitations. The last speaker in the session, Eugenia Kalnay, mostly famous for her data assimilation and NWP work, gave a really fascinating and passionate talk about her "hobby" interest of integrating ecological-economics into earth system modelling. For me, that was one of the highlights of the week.

Friday morning had a few interesting plenary talks about policy relevance, talking about things such as meningitis in Africa (apparently there's a big climatic link, which I didn't know before) and the importance of ensuring that climate-related information is actually both useful and usable. Then there were supposed to be presentations about the upcoming IPCC report, but unfortunately the speaker on WG1 (Qin) decided to waffle about Chinese glaciers instead - which might have been interesting as a scientific presentation but was woefully off-topic at that time. The ideas behind the WG2/3 structure were better presented by Chris Field. Some questions about how they were going to avoid making mistakes this time around were basically batted back with "you're our reviewers". Then there were a succession of summaries from the plenary sessions, followed by a question and answer session which got pretty boring pretty quickly so jules and I eventually gave up and went for an early lunch, as we had another meeting to attend in the afternoon.

Finally, at 4:30pm, 12 hours before we have to get up for our flight home, we finally managed the long-overdue jog along the Cherry Creek Trail...

WCRP OSC Day 3

Today was the busy day, with the schedule including two posters for me, a talk for jules, a business lunch and the conference gay-la (USAian pronunciation of Gala) party. Again, we didn't have the stomach for breakfast, especially after only having about 4h sleep.

Unfortunately, the plenaries were more posturing than science. Christian Jakob made the rather risible claim that physical climate modellers were an endangered species. I don't dispute that a significant emphasis has passed to the sexier chemistry/ecosystem/aerosol components of the climate system, and I don't have hard numbers to refute him with, but I find it very hard to believe that there are not still far more people now engaged in physical model development (he included numerics in this) than there were, say 30 years ago. Certainly our lab, which did not exist 15 years ago, boasts several groups of them, working on diverse aspects of climate modelling. He also promoted Tim Palmer's idea of a worldwide "Manhattan Project" to build one model to rule them all, and my only criticism of Gavin's rather unenthusiastic comment was that he was (predictably) rather too polite...

Adam Scaife of the Hadley Centre then did his best to cherry-pick some marginal successes out of the wreckage of their "decadal" prediction program, with such gems as the "likely to be globally hottest ever" forecast for 2010 (which wasn't actually hottest, by their preferred HadCRUT measure) and the "45% chance of cold" UK 2010 winter (ie 55% chance of warm or near-normal temperatures) which of course turned out to be remarkably cold. Interestingly, he didn't find time to mention the "most years past 2009 will be warmer than 1998" prediction of the Smith et al Science paper, which has failed to pan out for 2010, 2011 and most likely (based on ENSO forecasts) 2012 so far. Of course I must not be churlish about the improvements in the 3-10 day horizon and indeed ENSO forecasting which are notable in themselves, but perhaps they should stop pretending they can do much apart from that.

It was rather a relief when Sandrine Bony gave a nice review of what had (not) been learnt about climate sensitivity since the Charney Report, and why the model results had not converged since then (she didn't cover the probabilistic estimation approaches with the "long tail"). She made the point was that increased process understanding is a key component of reducing uncertainties in climate change predictions.

After coffee (and a remarkably heavy ham and cheese croissant), I had two posters to defend in different rooms, so focussed my attention on one of them. Having just received some encouraging reviews on a related manuscript, this will be the subject of another blog post in the near future. The one I abandoned was mostly a re-hash of the JClim paper which was finally published not long ago. A fair few people came by, though not necessarily the ones who really needed to read it...(but they might have seen it during the rest of the day).

The afternoon session was on reliability of climate models, which was supposed to be looking at CMIP5, but these results are only coming in around now so many people (including us) are still looking at CMIP3. Karl Taylor kicked things off with an unfortunate mis-statement regarding the interpretation of the multi-model ensemble (the stuff we have tried to correct in recent papers), but fortunately it wasn't a major part of the session, or even his talk. I found another virtually identical talk of his on the web here, the problem is on p32, I can rant in more detail if anyone cares...

Grant Branstator showed that the inherent predictability of the models on the decadal time scale varied substantially, which may help to explain the problems they are having. Sandy Harrison energetically and enthusiastically showcased what paleoclimate simulations (now part of CMIP5, for the first time) can offer in terms of model testing and validation, and Reto Knutti gave a nice overview of what (little) we know how to do in terms of evaluating and weighting climate models to improve their predictions. Both of these talks provided a fine background to jules' [brilliant -ed] talk on assessing model reliability and skill with paleoclimate simulations. She rattled though some of our recent work, and also some stuff that is yet to be written. So far our ideas have been developed and applied to the old CMIP3 models, so we look forward to seeing how the new crop of models measures up.

Conveniently, the aforementioned gala followed straight after, which was held in the local Denver art museum. To be honest, I was rather underwhelmed by the art, but that's probably just me.

WCRP OSC Day 2

Woke up in plenty of time this morning, but after several days here I have forgotten what it feels like to be hungry (or even slightly peckish) so we didn't even bother with breakfast.

The plenaries contained summaries of various observational data sets, specifically those relating to atmosphere, ocean and hydrology. Susan Wijffels seemed a little concerned that consensus had not yet been reached between several ocean data analysis efforts, but Peter Thorne made the counter-comment (with which I agree) that a diversity of approaches was a good thing to ensure robustness.

The poster session was before lunch, and I was defending the work I've been doing on last millennial temperature reconstructions - still unfinished, but after some interesting discussions I'm feeling sufficiently motivated to get it done soon. After lunch, there were updates on various reanalysis efforts, most of which seem to be (in contrast to the previous day's decadal prediction efforts) making great strides in both methods and data recovery. Peter Thorne tried his BEST to falsify my earlier prediction with a subtle reference to Muller :-) but nobody seemed to take the bait. The remainder of the session seemed a little technical and irrelevant so after a tea-time game of battleships with Gavin I gave up and went to the gym instead.

WCRP OSC Day 1

(You'll have to google your own links, due to computing/time/wifi limitations.)

Despite our best intentions ("Let's go for a dawn run along the Cherry Creek Trail!"), jetlag got the better of us and we only woke at 9am. Due to a prior appointment with a breakfast burrito, we missed most of the opening blurbs, but there was still plenty of acronym soup to go round. And I'm still not really much wiser about the actual purpose of it all...there's just enough politics mixed in with the science to be a little disconcerting, to me at least.

The plenaries have been mostly rather general, though there was an interesting (to me) talk on poorly-quantified aerosol effects. The parallel sessions were more detailed. Organisationally it has been a bit of a mixed bag - the setting seems very grand but there have been several presentation problems, and quite a few speakers are absent - including, to my amusement, someone who told one of their underlings on Friday that they were not attending, leaving said underling not only having to present, but even write, their 30 minute invited presentation over the next couple of days while at the conference.

I spent most of the day in the seasonal to decadal prediction session, which still remains rather a challenge. A few years ago, some meeting of the great and good decided that they were all going to do 30y forecasts, and unfortunately our institute took this suggestion rather more seriously than it deserved (in our opinion). Of course, skill beyond a couple of years (if that) has proved hard to find. The models do suggest a bit more potential predictability, but issues of model error and initialisation make this rather a challenge. Still, it's a good excuse for more funding.

Tim Palmer presented some good results from his stochastic parameterisation, but this work only extends to the seasonal time scale. Having started his talk with a complaint that all climate models were too similar, it was perhaps a little incongruous that he ended with an appeal for us all to club together to build a single climate model with stochastic parameterisations. I suppose you can't criticise one model for being too similar to itself :-) But it seems obvious to me that one model - even a stochastic one - cannot reasonably represent our uncertainties regarding the behaviour of the climate system over long time scales (and indeed if it did, then Jim Hansen would have got there 30 years ago.) There was a surprising amount of discussion throughout the session about the good performance of the multi-model mean, and I was relieved that another commenter saved me from having to suggest that an ensemble of (different) stochastically-parameterised models would outperform a single one.

Posters were enhanced by a reasonable quantity of free beer (that despite prior threats, was indeed "free as in beer"). But they weren't particularly on-topic for me, and I was flagging by then anyway.