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Posts Tagged ‘Metereology’

Behind Climate, Weather Is Still King

2009/02/22 5 comments

Twenty-third century historians debating who would be so anti-scientific as to associate an episode of extreme weather to climate, and especially to global warming, will have to look no further than two recent blogs on the recent Australian disaster:

A few things need to be firmly kept in mind:

With that in the background, let’s have a look at Brook’s work first. And it is not a pleasant one:

So, in Adelaide we have two freakishly rare extreme events happening with a 10 month period. How likely is that? Well, if the events are totally independent, we’d expect the joint likelihood of two such heatwaves (of 0.25% probability per year [the 2009 event] and 0.033% per year [2008 event], respectively), occurring within the same 12 month period, to happen about once every 1,200,000 years. Is that unlikely enough for you? But if there is ‘autocorrelation’ (dependencies between the two events due to a linked cause — such as climate change), this calculated probability is not valid.

If that isn’t a true example of why statistics have such a bad reputation (“lies, damned lies, and…”), then I do not know what is. And if that doesn’t show that Brook cannot properly talk about climate, as he doesn’t look like having even the faintest clue of what makes some days warmer than others, then I do not know what does.

And what does make some days warmer than others? Weather. By definition.

The 2009 Australian summer around Adelaide and Melbourne has seen some particularly hot days because of a peculiar weather pattern, with winds bringing hot, dry desert air towards the inhabited coast (there might have been also an intervening Foehn (warming) effect, but let’s keep that aside for the moment).

The underlying weather pattern has been described by the National Climate Centre at the Australian Government’s Bureau of Metereology:

The presence of a slow-moving high pressure system in the Tasman Sea, combined with an intense tropical low off the northwest coast of Western Australia and an active monsoon trough, provided the ideal conditions for hot tropical air to be directed over the southern parts of the continent

NASA’s Land Surface Temperature Anomaly picture reinforces this point: one can clearly see how warm air has been pushed towards Victoria, just as cool air towards Queensland. And an intervening band in the middle has then experienced whatever temperatures it usually experiences.

It’s just the same air movement. If you push “oceanic air” over Queensland, the existing “Queensland air” will move towards Victoria, and so on and so forth closing the high-pressure system circle somewhere to the East of Australia. You can get a similar result with a low-pressure system somewhere to the West too. If the two combine, so much more evident the Queensland cooling and Victoria warming. Does one need to be a veteran metereologist to understand such an easy point?

Even the briefest introduction to metereology and climatology should  make very clear to everybody how incredibly naïve and totally anti-scientific is the belief that “global warming” means hotter days in this or that part of the planet. In fact, the question Brook should have asked is: do that “slow-moving high-pressure system” and “intense tropical low” in those particular places, and that “monsoon trough”, have anything to do with (anthropogenic) climate change?

But of course Brook just about cannot get anywhere in that direction

the heatwave that struck Europe is 2003 provides a good way to illustrate my final point, thanks to a neat analysis published in Nature in 2004

Who knows, one day he may wake up to a 2007 paper, three years later that is, by Chase et al. published in the Geophysical Research Letters, asking “Was the 2003 European summer heat wave unusual in a global context?” and responding

Regression analyses do not provide strong support for the idea that regional heat or cold waves are significantly increasing or decreasing with time during the period considered here (1979–2003)

I am all for free speech, and Brook and the likes can keep on blaming perversity for the worst kind of climate change denial but there must be a point where they have to recognize how silly it is to appeal to science without understanding a iota of it.

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Karoly’s contribution is of a different quality, with no absolute-weather-beginner mistaken mention of reality-divorced probabilities (Karoly even talks, briefly, about weather patterns…).

His point appears to be a rather old one though. Why would heatwaves be attributable to anthropogenic global warming? Because Karoly himself, with Braganza, managed some time ago to simulate observations using climate models that include “increasing atmospheric greenhouse gases and aerosols” (see his 2004 paper referred to in the blog).

Actually, to be more precise, what happened is that Karoly and Braganza were unable to simulate observations using “natural climate variations alone“. Perish the thought that the problem might have been an inappropriate definition of those “natural climate variations”…

In any case, given the apparent strength of Karoly’s convictions dating from 2004, one might start wondering why the Chair for the “Detection and Attribution: State of Play in 2009” (Parallel Session 9) in Copenhagen would be Ann Henderson-Sellers of all people. Who she? The one claiming in the session’s very description that

the detection and attribution story was incomplete [at the time of the IPCC AR4 in 2007] due to ‘Key Uncertainties’ listed by IPCC

and listing in a September 2008 article, among the seven “Serious inadequacies in climate change prediction that are of real concern

  • The rush to emphasize regional climate does not have a scientifically sound basis […]
  • Until and unless major oscillations in the Earth System (El Nino-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) etc.) can be predicted to the extent that they are predictable, regional climate is not a well defined problem. […]

Notice how Henderson-Sellers goes on to say that “WGII is easily the weakest of the three reports. The reasons seem to be two-fold: (i) poor downscaling and (ii) the lack of a coherent methodology for impact study“.

I am sorry for Prof. Karoly but either Prof. Henderson-Sellers is very wrong on more than one point (and then what would she be doing as Chair of one session in Copenhagen?); or Karoly’s own 2004 work, and his present stance are just an example of what Henderson-Sellers describes as the rushed, scientifically unsound regional climate emphasis around a non-well-defined problem, plagued by poor downscaling and dealing with a climatic impact without a well-recognized methodology.

Does Karoly understand this problem? I think he does. Cue his large caveat about his large claim

Although formal attribution studies quantifying the influence of climate change on the increased likelihood of extreme fire danger in south-east Australia have not yet been undertaken, it is very likely that there has been such an influence

Karoly’s own language gymnastics is remarkable, with just about the right mix of “clear” and “likely” to pass most logic tests, in case things don’t turn up as expected. He’s not the first athlete to enter such a competition though.

Finally, it certainly doesn’t look too good when Karoly provides three papers linking “observed and expected increases in forest fire activity […] to climate change” but no mention of the lack of any comprehensive analysis (think of the absence of trends in fires around the Mediterranean region for example).

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It is rather sad to see what started as the science of climate turning pretty much into a parody, with reports and explanations forever running after the latest disaster. Very simply, this cannot be right.

More on RealClimate’s Unfalsifiable Models

2008/04/24 13 comments

This being the age of the Internet, not everybody reads after the second or third paragraph. So here’s a quick summary explaining why I write that “RealClimate Raises the Bar AGAINST Climate Models“:

(1) In the “RealClimate World”, models cannot be falsified by a single observation (i.e. atmospheric phenomenon). That  phenomenon is called ”weather”, and “weather” for RealClimate isnoise”)

(2) In the “RealClimate World”, models cannot be falsified by a set of short-term observations. That set is just part of a “specific trajectory” towards the expected climate change / global warming. And RealClimate is “not too concerned” about a “specific trajectory“.

Example for point (1): If models indicate the world will get warmer by the year 2100, but world temperatures dip in January and February 2008, RealClimate can still “honestly” claim the models are right, and whatever happened is just a momentary event, during which the “signal” of anthropogenic global warming has been “obscured” by this or that natural (or man-made) cause.

Example for point (2): If models indicate the world will get warmer by the action of CO2 and other greenhouse gases, but world temperatures don’t climb after 1998, RealClimate can still “honestly” claim the models are right, and whatever happened is just the way things are going at the moment, with a random pause in temperature increases that is just one of the hundreds of possible “trajectories” that will take us to a warmer world.

The only way to verify if the climate models are right is by waiting a sufficient number of years in order to statistically check the world has actually got warmer. How many years? More than 10, evidently (see 1998), perhaps more than 30, following the classical definition of “weather”. And by how much, the temperature increase? Pretty much any positive amount would suffice to state, once again, that the “models are right”.

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This looks like some kind of “suffocating love”, with the modellers so worried about their models, they have shielded them from almost all possibilities of falsification (in the process, pretty much abandoning “science” as usually understood).

And this is not the only contradiction: if the only way to see the models at work is by waiting a number of years, how could anybody advocate to “act now to save the Planet” because “the science is settled”?

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The issue of model falsifiability has already been a topic on the NYT’s “Tierney Lab”, daring to ask this past January questions such as “Are there any indicators in the next 1, 5 or 10 years that would be inconsistent with the consensus view on climate change?” and “Are there any sorts of weather trends or events that would be inconsistent [with global warming}?“.

And what did Gavin Schmidt reply on RealClimate? No, and no:

this subject appears to have been raised from the expectation that some short term weather event over the next few years will definitively prove that either anthropogenic global warming is a problem or it isn’t. As the above discussion should have made clear this is not the right question to ask. Instead, the question should be, are there analyses that will be made over the next few years that will improve the evaluation of climate models?

No “short-term weather event over the next few years” could ever disprove that “anthropogenic global warming“. And observations (events) and their analyses, in the RealClimate world, are only interesting to “improve the models“.

It’s hard to fail to spot in Schmidt’s reply that they did go back to “Hansen’s 1988” and other old projections, but whilst the bits that agree with the models are signs that those projections are “good“, those that disagree are so “for reasons that are as yet unclear“.

Instead of scientists trying to interpret the world, in RealClimate we have people subordinating the world to their models.

RealClimate Raises the Bar AGAINST Climate Models

2008/04/24 13 comments

With the death of Ed Lorenz and a world apparently taking a hiatus on the way to unstoppable anthropogenic global warming, It has taken a group effort at RealClimate to try to deal with the issue of chaotic weather vs. climate modelling: “Butterflies, tornadoes and climate modelling“.

Rather unfortunately for the authors, the conclusions contain a remarkable amount of unintended irony.

[…] But how can climate be predictable if weather is chaotic? The trick lies in the statistics. In those same models that demonstrate the extreme sensitivity to initial conditions, it turns out that the long term means and other moments are stable. […] Climate change then is equivalent seeing how the structure changes, while not being too concerned about the specific trajectory you are on

In other words, “climate change” is an entity that can only become observable in the long, long term. And since there is little concern for the “specific trajectory”, there literally exists NO possible short-term sets of observations that can falsify the climate models.

Another way of saying it is that for the climate problem, the weather (or the individual trajectory) is the noise. If you are trying to find the common signal that is a signature of a particular forcing then averaging over a number of simulations with different weather works rather well […]

In other words, since each and every atmospheric event can be obviously described as “weather”, there is no single observation that can falsify the climate models.

Their work doesn’t have to deal with any single observation, no short-term sets of observations…do they realize what they are saying???

Real climate is in their own words almost perfectly insulated from the real world. Nothing that can ever happen will be able to disprove the work of the climate modellers, apart from multi-decadal averages that are so poorly defined, they can easily be used to demonstrate anything.

Is this “science”? Looks more like long-term guaranteed employment to me… No wonder Anthropogenic Climate Change has important detractors in the metereological community.

In further irony, the above pairs up perfectly well with RC’s “comments policy” that can be summarized more or less into “we will censor everything we do not like“.

RealClimate: the insulated web site, where insulated researchers post insulated content. Now I understand why poor Gavin Schmidt had such a hard time dealing with an open debate

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