“The weather forecast looks sunny and particularly hot from Sunday to Friday, with afternoon temperatures above 30°C every day, and likely exceeding 35°C by the middle of the week. One consequence is that the poster sessions (Tuesday and Thursday) have been moved to the morning as they will be held outside under a marquee.”
I have never received a notification like this before a conference. And it was then followed up by a warning from the Guardian: ‘Hell is coming’: week-long heatwave begins across Europe.
The heatwave took place and was an appropriate frame for the International meeting on statistical climatology (IMSC), which took place in Toulouse, France (June 24-28). France set a new record-high temperature 45.9°C on June 28th, beating the previous record 44.1°C from 2003 by a wide margin (1.8°C).
One of the topics of this meeting was indeed heatwaves and one buzzword was “event attribution”. It is still difficult to say whether a single event is more likely as a result of climate change because of model inaccuracies when it comes to local and regional details.
Weather and climate events tend to be limited geographically and involve very local processes. Climate models, however, tend to be designed to reproduce more large-scale features, and their output is not exactly the same as observed quantity. Hence, there is often a need for downscaling global climate model results in order to explain such events.
A popular strategy for studying attribution of events is to run two sets of simulations: ‘factual’ (with greenhouse gas forcing) and ‘counterfactual’ (without greenhouse gas forcings) runs for the past, and then compare the results. Another question is how to “frame” the event, as different definitions of an event can give different indicators.
Individual heatwaves are still difficult to attribute to global warming because soil moisture may be affected by irrigation wheras land surface changes and pollution (aerosols) can shift the temperature. These factors are tricky when it comes to modeling and thus have an effect on the precision of the analysis.
Nevertheless, there is little doubt that the emerging pattern of more extremes that we see is a result of the ongoing global warming. Indeed, the results presented at the IMSC provide further support for the link between climate change and extremes (see previous post absence of evidence).
I braved the heat inside the marquee to have a look at the IMSC posters. Several of them presented work on seasonal and decadal forecasting, so both seasonal and decadal prediction still seem to be hot topics within the research community.
A major hurdle facing decadal predictions is to design climate models and give them good enough information so that they are able to predict how temperature and circulation evolve (see past post on decadal predictions). It is hard enough to predict the global mean temperature (link), but regional scales are even more challenging. One question addressed by the posters was whether advanced statistical methods improve the skill when applied to model output.
A wide range of topics was discussed during the IMSC. For instance, how the rate of new record-breaking events (link) can reveal trends in extreme statistics. There was one talk about ocean wave heights and how wave heights are likely to increase as sea-ice retreats. I also learned how severe thunderstorms in the US may be affected by ENSO and climate change.
Another interesting observation was that so-called “emergent constraints” (and the Cox et al, (2018) paper) are still debated, in addition to methods for separating internal variability from forced climate change. And there is ongoing work on the reconstruction of temperature over the whole globe, making use of all available information and the best statistical methods.
It is probably not so surprising that the data sample from the ARGO floats shows an ongoing warming trend, however, by filling in the spaces with temperature estimates between the floats, the picture becomes less noisy. It seems that a better geographical representation removes a bias that gives an underestimated warming trend.
While most talks were based on statistics, there was one that was mostly physics-based on the transition between weather regimes. Other topics included bias-adjustment (multi-variate), studies of compound events (straining the emergency service), the connection between drought and crop yields, how extreme weather affects health, snow avalanches, precipitation from tropical cyclones, uncertainties, downscaling based on texture analysis, and weather generators. To cover all of these would take more space than I think is appropriate for a blog like this.
One important issue was about data sharing which merits wider attention. The lack of open and free data is still a problem, especially if we want to tackle the World Climate Research Programme’s grand challenges. European and US data are freely available and the Israeli experience indicate that open access is beneficial.
103 nigelj sez: (quoting yours truly) “In any case, a careful, critical study of worldwide temperature distributions during the period in question would be necessary”
nj: We already have the global graph we are discussing, which is based on country by county data!
V: Really? Can you provide a reference?
nj: Come back to basics. It doesn’t matter too much about the exact degree of warming mid century. Temperatures in the northern hemisphere fell very noticeably, and this is where most of the industrial aerosols are concentrated and tend to linger so no surprise there they pushed temperatures down.
Temperatures in the southern hemisphere clearly follow a different trend, they warmed slightly overall, but fell slightly in some places like Africa over land, but the point is they did not fall as much as the northern hemisphere. This is clear in the graphs people have posted.This pattern is ALL consistent with less industry being in the southern hemisphere, and some drift of aerosols from the north so temperatures were pushed down, but NOT AS MUCH.
V: Yes yes yes. The cooling effect of industrial aerosols, like that of volcanic aerosols, is well known. So it’s not surprising to see cooler temperatures in more highly industrialized regions. So what? That’s beside the point. I’m not arguing that aerosols don’t have a cooling effect. I’m looking for the underlying WARMING trend, supposedly produced by rapidly rising CO2 emissions during the period in question — warming supposedly masked by the cooling effect of aerosols in highly industrialized regions. If that were the case, then we’d expect to see warming trends in regions where industrial aerosols are not a significant factor. Which is why I feel a systematic region by region study of atmospheric temperatures in relation to aerosol density is necessary before any conclusion can be drawn. Not sure why this is so hard to understand.
V 108: I’m not arguing that aerosols don’t have a cooling effect. I’m looking for the underlying WARMING trend, supposedly produced by rapidly rising CO2 emissions during the period in question
BPL: Then you need to statistically remove the aerosol effect from the regression and see what remains. Do you know how to do this?
Killian @100, you should repost that on the proper forestry thread. I realise it was a simple mistake clicking on the wrong thread everyone does it.
Victor @108
“nj: We already have the global graph we are discussing, which is based on country by county data!”
“V: Really? Can you provide a reference?”
How do you think the global data for the two hemisphere is derived? Its based on taking temperature data for the oceans and countries, and adding it together and deriving an average. You can get a feel for where the data comes from in this map below. Please note each dot represents more than one weather station and there are many thousands of weather stations, and ships also measure the warming of the oceans.
https://databasin.org/datasets/15a31dec689b4c958ee491ff30fcce75
“V: Yes yes yes. The cooling effect of industrial aerosols, like that of volcanic aerosols, is well known. So it’s not surprising to see cooler temperatures in more highly industrialized regions. So what? That’s beside the point. I’m not arguing that aerosols don’t have a cooling effect. ”
Oh really? You have written numerous posts on this website disputing that aerosols have a cooling affect. Nice to see you have finally woken up. Like Bob Dylan says its a slow train coming.
“I’m looking for the underlying WARMING trend, supposedly produced by rapidly rising CO2 emissions during the period in question — warming supposedly masked by the cooling effect of aerosols in highly industrialized regions. If that were the case, then we’d expect to see warming trends in regions where industrial aerosols are not a significant factor. Which is why I feel a systematic region by region study of atmospheric temperatures in relation to aerosol density is necessary before any conclusion can be drawn. Not sure why this is so hard to understand.”
There are few areas where aerosols are not a significant factor. Some drift virtually everywhere. But in your comments at 97 you did produce a graph for the solomon islands showing a warming trend, and they are a place in the south pacific as isolated form aerosols as any, so you have largely answered your own question.
Remember the warming effect of CO2 immediately after WW2 was quite weak anyway so any warming trend without aerosols would be weak or possibly due to regional factors.
Move on. Apply your Sherlock Holmes abilities (and you do have some) to some other aspect of things and stop being a repetitive bore.
MA Rodger (@104): Your inclusion of Victor’s last name and city of residence is uncomfortably close to doxing and irrelevant. I usually defend the moderators’ right to manage the comments as they see fit, but in this case I urge them to curtail this.
Weaktor, It is just a pleasure to watch your mind churn on this problem, but then I’ve always had a cruel streak.
Sorry, may have missed it amongst all the blather:
Does someone have a falsifiable prediction (about something important, say decadal global surface temps) that’s clearly at odds with mainstream climate science?
If, for example, blather about the mid 20th century led to a prediction that the 2020’s, or 2030’s, or 2040’s would be cooler than 2010-2019, I have a home-mortgage-size bet that I’d like to discuss.
If not, well, at least online blather kills fewer trees.
About victor et al:
It has been said “the debate is over” quite some years ago, but still climate scientists debate with ignorant deniers, it’s a charade, like some bizarre circular canon on the way to hell. The deniers are making fun of you and they are right to do so.
Don’t waste precious time, don’t feed the trolls.
#109 V 108: I’m not arguing that aerosols don’t have a cooling effect. I’m looking for the underlying WARMING trend, supposedly produced by rapidly rising CO2 emissions during the period in question
BPL: Then you need to statistically remove the aerosol effect from the regression and see what remains. Do you know how to do this?
V: I’m not the one making the claim. The burden of proof is with those who insist on the existence of that underlying warming trend. The fact that the cooling trend in question can — hypothetically — be explained by the presence of industrial aerosols is NOT in itself sufficient to support the existence of an underlying warming trend. Anyone wishing to make such a claim needs to back it up with evidence that this hypothetical warming trend actually happened. I’ve already presented examples of relatively unindustrialized regions where no such warming trend can be seen, but I’m not a climate scientist and not in a position to do the research necessary to weigh all the relevant evidence. And I’m wondering whether a study of that sort has already been done. If not, then I see no reason to accept the claim that an underlying warming trend ever existed during this 40 year period.
MartinJB @112,
Our dear friend Victor the Troll has in the past come here using Victor Grauer as a user name so there should be no objections on that score. And do I recall correctly that he has also returned here hiding behind a pseudonym? Or was it elsewhere?
As for his home city, I don’t think he initially offered it, if he ever offered it, but his performance here (and elsewhere) has been so dire that it has led to folk asking who this idiot Victor actually is, with others soon offering a Victor CV.
Our hosts are not the most festidious of moderators. If you look back to the early days, the Bore Hole was seeing daily additions. Today it receives far less yet without the efforts of the likes of our dear friend Victor the Troll, those few who persist with their foolishness long beyond its sell-by date, the Bore Hole would remain almost unused – Victor managed to clock-up over a third of the Bore Hole additions for 2018.
Victor, #116–
So, you’re not claiming that there’s a cooling trend in the SH incompatible (sez you) with AGW during the mid-20th century. Gee, I was almost sure that was what you were saying…
Guess that’s an answer of sorts to my question as to whether V would try to find said study. Can’t be bothered, apparently…
V 116: The burden of proof is with those who insist on the existence of that underlying warming trend.
BPL: And it has been demonstrated, but you refuse to accept standard statistics.
Moderators! Can you not borehole K.I.A. and Victor???? They’re MAGA Morons. They’re inhibiting the discussion and spamming the threads. This has been going on for a really long time.
MAKE IT STOP!
Kevin McKinney: Guess that’s an answer of sorts to my question as to whether V would try to find said study. Can’t be bothered, apparently…
AB: True. Because until somebody does Victor’s precise studies and they are reported on exactly as Victor demands, it’s all goop by definition.
Yo, Vic! There’s more than one way to figure out a fact. Some ways are more robust, accurate, and/or expensive. The way it works is that when a study passes peer review the burden of proof switches to YOU (or whomever thinks the study is bunk).
Keven McKinney @118
Victor works very hard at his denialism. Yup, he misses nothing that might possibly support his egotistical rejection of science. He can dig out the most mundane and inconsequential detail if he can twist it to attack the science. But then when it comes to what the science actually tells us, it is always the same lame excuse that he is not an expert and not capable of doing the research or evaluating it. He always demands others provide him with the evidence and information that is readily accessible if he were to just look for it himself and states that without it he will refuse to accept the science. Very convenient. This as if anyone actually cares what he thinks. Sad, really.
To the scientists monitoring this blog: would one of you please take some time to explain to the peanut gallery the meaning of the scientific principle known as a “control”? Thank you.
Victor
RE. #123
My guess would be that V understands *control* in science just as well as he understood *correlation*
Do you think it possible that human kind could ever, by whatever means, change the climate of the Earth?
MkP 125: Do you think it possible that human kind could ever, by whatever means, change the climate of the Earth?
BPL: Yes. In fact, we’re doing so by adding more CO2 to the atmosphere.
Sea level rise further constrained, new study: Mean SL of 16m, 5.xm on the low end at current temps.
No skyrockets, not even a sparkler, just the facts, ma’am.
Yup.
Told ya.
One choice: Return to pre-industrial to minimize the rise.