Thursday, November 28, 2019

What "you can't believe the modelling" looks like

Tamino at Open Mind has done an updated bit of graphing, and while it looks a lot like what Gavin Schmidt does from time to time, it's worth publicising anyway:
I took the data for global average temperature from climate model simulations in the CMIP5 archive; those are computer models used in the latest IPCC report. I used only those models with the “RCP4.5” emissions scenario (a middle-of-the-road choice). I then aligned them all so their average value was zero during the 1961-1990 “baseline” period. Finally, I calculated yearly averages for each of the 108 models included.

That enables me to compute the “multi-model mean,” the average of all the models at each moment of time. Also at each moment of time, I computed the standard deviation of the model values and recorded the highest and lowest model values (which can be different models at different times).

Now I can graph the multi-model mean over time as a thick red line, together with a yellow outermost envelope showing the range from highest to lowest, a tan-colored middle range the limits of the 2-sigma range (about 95% of the models) and a pink band the 1-sigma range (about 2/3 of the models).

And I can also plot actual observed global temperature from NASA (yearly averages using the same 1961-1990 baseline) as a black line:
 Someone in comments notes that Ross McKitrick has done a similar thing, but it's not as good as it ignoring coverage bias with HadCRUT.  Yet, when you look at his graphing, it still indicates a relentless climb, just lower in the "pink" band.   Which makes his scepticism look kinda pointless...

10 comments:

Not Trampis said...

Hey I wrote about this today!!

Steve said...

Sorry, I don't check your blog to see if you got there first..:)

Not Trampis said...

Mine is the expurgated view

Anonymous said...

Hey, I can create nice art like that.

Steve said...

A real science-y contribution there, JC (I presume).

You could just change it to "all climate scientists are poopy heads" and it would be just as useful, and as indicative of your mindset.

Not Trampis said...

JC could not do anything like that.
He is innumerate.

mind you he could make it up

GMB said...

"I took the data for global average temperature from climate model simulations in the CMIP5 "

Stop right there. Thats not data. So its useless. From the first sentence onward we see that nothing he is going to say is of any scientific merit. In fact he doesn't even know what data is.

GMB said...

The model doesn't even backtest. These people are clowns. You look at the staff they aren't even fake scientists. They are instead fake journalists.

GMB said...

Its incredible how this works. First they rig the data. Then they produce models based largely on the rigged data. So the model doesn't backtest. Then they project this wrong data and flawed models forward. Then they put in their thumb and pull out a plumb and say what a good boy am I. The science is settled. They are so fucking useless they ought to consider castration so as to not pass on the stupid gene.

Anonymous said...

Paxton, stop being a complete moron.