Saturday, November 24, 2012

Back to the Future Once More

Every now and then some little obnoxious bunny goes nah nah global temperatures haven't risen in whatever years, everything is not known, natural variability is natural.  Eli knows the patter and all the Rabett has to do is wander over to Kloor's to find the music should he forget

  1. Tom Fuller Says:
    Steve Fitzpatrick, I don’t believe science claims to have a good grip on all of the factors you describe. More pertinent to the discussion, back in the late 80s and 90s nobody was talking about those factors when temperatures were rising swiftly, alongside emissions. In fact they said that the response was both quick and expected–even expectable.

    So to me it sounds like you are bringing in partially understood factors to explain away the sudden decorrelation of temperatures and emissions–I’m sorry if I’m misinterpreting you.

    In any event, one quarter of all human emissions in the past 14 years with no discernible effect. That takes a lot of explaining.
So every once and a while the pall of Alzheimer's lifts and Eli does remember back 24 or so years ago when he read a certain paper by someones called Hansen, Fung, Lacis, Rind, Lebedeff, Ruedy, Russell, and Stone, 1988: Global climate changes as forecast by Goddard Institute for Space Studies three-dimensional model. J. Geophys. Res., 93, 9341-9364, doi:10.1029/JD093iD08p09341.

No, not the usual ABC blather from the seemers and deniers, but something that pops out at anybunny who actuall reads the thing.

 They ran a century control run with greenhouse gas concentrations fixed at about the 19858 values with heat exchange across the maximum mixed layer depth in their ocean model so that it would respond quickly to changes in natural variability, and they compared the variability to that observed between 1951 and 1980
there is substantial unforced variability on all time scales that can be examined, that is up to decadal times scales.  Note that an unforced change in global temperature of about 0.4 C (o.3C, if the curve is smoothed with a 5-year running mean) occurred in one 20 year period (years 50-70).  This unforced variability of global temperature in the model is only slightly smaller than the observed variability of global surface air temperature in the past century, as discussed in section 5.  The conclusion that unforced (and unpredictable) climate variability may account for a large protion of climate change has been stressed by many researchers;  for example, Lorenz (1968), Hasselmann (1976) and Robock (1978)
They also looked at the spatial variation and variation with  latitude and altitude

The standard deviation ranges from about 0.25 C at low latitudes to more than 1 C at high latitudes in both models and observations.  The model's variability tends to be larger than observed over continents;  this arises mainly from unrealistically large model variability (by about a factor of 2) over the continents in summer as shown by the seasonal graphs of Hansen and Lebedeff (1987).
 and indeed, the discussion of the paper's results for global temperature trends (the famous Figure 3) IS centered on the relationship of the predicted trends to natural variability and the variability in the model.  It was the ability of the model to match natural variability, at least on a global and latitudinal scale that gave confidence in its performance when forced by increases in greenhouse gases and volcanic eruptions.

 Interpretation of Figure 3 requires quantification of the magnitude of natural variability in both the model and observations and the uncertainty in the measurements.  As mentioned in the description of Figure 1, the standard deviation of the model's global mean temperature is 0.11 C for the 100 year control run, which does not include the thermocline.  The model simulations for scenarios A, B and C include the thermocline heat capacity, which slightly reduced the model's short term variability; however judging from the results from scenario A which has a smooth variation of climate forcing, the model's standard deviation remains about 0.1 C.
There is more, but Ms. Rabett calls.


dhogaza said...

Ironic coincidence that the spambot has posted as "kk" ...

dhogaza said...

Ugh, I read that thread.

Which leads to the endless and unaswerable question:

Who is more despicable?

Tom Fuller or his co-auther Mosher?

David B. Benson said...

Is this thread going to go somewhere?

Aaron said...

I would call the loss of ice and permafrost in the Arctic, "a large discernible affect"

It was good to remember that the 1988 estimate of standard deviation of global temperature was 0.11C. That means current warming is ~6 sigma off of a 1988 baseline.

i was trained that 6-sigma events "do not just happen" If one finds a 6-sigma event, then somebody has made a bad mistake.

Lars Karlsson said...

A correction: the control run in Fig 1 was with 1958 values, not 1988 values.

EliRabett said...

Tip o the ears. Many thanks

Marion Delgado said...

There are about a half dozen things that indict Kloor as a faux journalist, but the worst by far is his embrace of Tom Fuller. By the way, the real issue with Kloor is not that he's entirely dreadful, but why he merits anyone's attention, ever; it's precisely what needs to be asked about the myriad pundits-for-being-pundits and everyone who writes for the Atlantic. The short answer is: nothing. The Kloors, David Brooks, etc. of the world add nothing but self-praising retwisting of whatever the Republican Party's current backers want the public to believe is common sense or at least conventional wisdom.

Anonymous said...

In any event, innumerable warnings from scientists in recent years about the uncertainty of short term trends with no discernible effect on Kloor. That takes a lot of lying.