Kudos to RealClimate’s Honesty and Sincerity

And no, I am not being sarcastic.

It’s just that (finally!) there is a RC claim that can be compared to the real world; next to it, a good dose of outright sincerity (surely it must have been there before,  perhaps buried in the polemic…)

From What the IPCC models really say (May 12, 2008):

• Claims that GCMs project monotonic rises in temperature with increasing greenhouse gases are not valid. Natural variability does not disappear because there is a long term trend. The ensemble mean is monotonically increasing in the absence of large volcanoes, but this is the forced component of climate change, not a single realisation or anything that could happen in the real world.
• [...]
• Over a twenty year period, you would be on stronger ground in arguing that a negative trend would be outside the 95% confidence limits of the expected trend (the one model run in the above ensemble suggests that would only happen ~2% of the time).

Note that even the fabled 20-year negative trend may still be interpreted as consistent with at least one model run.

But it’s a good step in the right direction: bringing back climate science from its forcings cage to the actual world…

Climate Change Detection/Attribution? Some Hope!

Curious situation on the website of the PCMDI - the “Program for Climate Model Diagnosis and Intercomparison”, at the Lawrence Livermore National Laboratory, with a stated mission:

to develop improved methods and tools for the diagnosis and intercomparison of general circulation models (GCMs) that simulate the global climate

Here’s what the PCMDI has to say about “devising robust statistical methods for climate-change detection/attribution“:

Coming soon…

That’s it.

Wow.

Sure.

Well, it looks like we will just have to be patient. We will be told how to detect and attribute climate change…one day, perhaps after some considerable amount of time will have ben spent in the frankly rather wasteful efforts of mostly comparing climate models to each other, rather than to the actual world.

p.s.: Applause to the PCMDI for their frankness:

The need for innovative analysis of GCM climate simulations is apparent, as increasingly more complex models are developed, while the disagreements among these simulations and relative to climate observations remain significant and poorly understood. The nature and causes of these disagreements must be accounted for in a systematic fashion in order to confidently use GCMs for simulation of putative global climate change.

Aristotle’s Climate Model

Greek philosopher Aristotle may have written the first treatise on Meteorology, around 350BC. He postulated the existence of five geographical zones: Frigid (one North, one South) by the poles, Torrid (North and South of the Equator) and Temperate (one North, one South) in-between the relative Frigid and Torrid zones.

Remarkably, that subdivision still holds. One of Aristotle’s ideas has not survived the test of time though: contrary to his thoughts, the Torrid Zone is not devoid of life and especially of human life due to excessive warmth.

And so we can say that Aristotle was totally wrong. Or was he?

Let’s perform some quick computations using modern readings and the world as known by ancient Greeks.

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Consider Alexandria and Aswan, in Egypt, the cities used by Eratosthenes of Cyrene to measure the accurately measure the size of the Earth (around a century after Aristotle’s time).

From the BBC Weather website, temperature statistics for both cities can be computed

Alexandria (31 degrees North):
Average monthly Min: 17.3C
Average monthly Max: 24.9C
Average yearly: 21.1C

Aswan (24 deg N):
Average monthly Min: 19.1C
Average monthly Max: 34.25C
Average yearly: 26.7C

Now, since we know there are 7 degrees of latitude between the two cities, we can compute at what rates temperatures increase going south from Alexandria to Aswan:

Temperature increase by degree of Latitude:
Average monthly Min: 0.26C/deg
Average monthly Max: 1.33C/deg
Average yearly: 0.798C/deg

What is the expected temperature at the Equator (Latitude: zero, thus 24 degrees south of Aswan), assuming those rates don’t vary (i.e. temperature trends can be modelled in linearly)?

Equator (zero deg):
Expected Average monthly Min: 25.5C
Expected Average monthly Max: 66.3C
Expected Average yearly: 45.85C

Look at those temperatures…if those were true, truly the Equator would be more or less uninhabitable.

Therefore: Aristotle’s idea of a “Torrid Zone” was not a philosophical fantasy, but a reasonably estimation compatible with what was known during ancient times.

=================

Of course we know the actual values are different. For example:

Kinshasa (4 deg N):
Average monthly Min: 20.7C
Average monthly Max: 30.4C
Average yearly: 25.5C

That makes Aristotle’s Climate Model wrong of an amount between 5C and 36C.

=================

So what are the lessons to take home?

(1) Climate models that appear perfectly reasonable today can be shown to be very, very wrong tomorrow

(2) Extending a trend means just making an estimation that can be way off reality, especially if the trend is presumed linear

(3) Temperature is NOT everything. Actual climate depends on a lot of other things.

At the Equator, like everywhere else on the planet.

Ocean Circulation May or May Not Weaken with Global Warming

Ocean circulation in a warming climate - J. R. Toggweiler & Joellen Russell
Nature 451, 286-288 (17 January 200 | doi:10.1038/nature06590; Published online 16 January 2008
Abstract: Climate models predict that the ocean’s circulation will weaken in response to global warming, but the warming at the end of the last ice age suggests a different outcome.

And so AGW studies start resembling dieting advice. Whatever you like to eat, just wait long enough and some paper will say it’s good for you.

ps a more serious note: how much more exciting would climatology be, were it not poisoned by all the save-the-planet agitation!!