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Posts Tagged ‘Real Climate’

Climate Models Are Irrelevant, and Latest IPCC Models a Regression

(many thanks to LM for pointing this out)

  • “[GCM] model outputs at annual and climatic (30‐year) scales are irrelevant with reality
  • model predictions are much poorer that an elementary prediction based on the time average
  • The GCM outputs of AR4, as compared to those of TAR, are a regression in terms of the elements of falsifiability they provide, because most of the AR4 scenarios refer only to the future, whereas TAR scenarios also included historical periods

Those are not the insane ramblings of yours truly, but the conclusions of D. Koutsoyiannis et al’s “Assessment of the reliability of climate predictions based on comparisons with historical time series“, a poster presentation at the European Geosciences Union General Assembly 2008 in Vienna, Austria, 13‐18 April 2008.

Of course, it’s only a poster presentation…and of course, there was really no space at all to talk about it in the news, eg on the BBC.

Well, there is one good thing that has come out of this though: some explicit references in RealClimate about the need to have “a very civilized and friendly chat, “to be respectful, sincere, and show courtesy in our criticism, even when we argue why we think that a paper has flaws“, and that “we some day may be mistaken, so it’s important to be humble and check our drafts amongst ourselves“.

This will mean no more verbal attacks about “negationism”, and few if any displays of condescension. Sure it will… 

Climate Models: How Much Difference is Too Much Difference?

2008/05/02 5 comments

Does anyboy know the answer?

I re-post here a comment I just left at RealClimate (one never knows what gets published over there, and what doesn’t…)

Re: #101 As a matter of fact if you search on PubMed http://www.ncbi.nlm.nih.gov/pubmed/ there are four articles with my name. In two of them I appear as first author. And no, they are not first-rated earth-shattering Science or Nature articles about climate science.

But as we all agree now, that’s beside the point.

Let’s me start again from a simple question. Hansen et al did compare model results to observations.

“Climate simulations for 1880–2003 with GISS modelE”, Clim Dyn (2007) 29:661–696 – DOI 10.1007/s00382-007-0255-8

For example, consider fig. 9 (the PDF of the article is on the internet, apologies but I do not have time to search for it right now):

“Fig. 9 Global maps of temperature change in observations (top row) and in the model runs of Fig. 8, for 1880–2003 and several subperiods. […]”

Observations there are shown in periods respectively of 124 years (1880-2003), 54 years, 61 years, 40 years and finally 25 years (1979-2003).

Presumably, this provides a first approximation of what time spans are needed to talk about climate (around 25 years). The actual shortest period may be 40 years or longer, as 1979-2003 has been chosen primarily as “the era of extensive satellite observations”. Please correct me if am wrong.

Let’s take now a clear-cut example. The authors write “All forcings together yield a global mean warming ~0.1C less than observed for the full period 1880–2003.”. And that’s a remarkable result.

But…may I ask this rather elementary question: say, if the global mean warming yielded by all forcings together had been much less, or much more than observed, what would have been the (absolute) threshold above which the climate simulations would have been declared a failure?

Or has this question no meaning either? If not, why not?

Once again, I am consciously simplifying things here but this is a blog…more a brainstorming session than a week-long workshop.

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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