2 February 2005
of Climateprediction.net claim (as published in their January 2005 Letter
to Nature) that their modelling indicates 11 degrees C global temperature
rise is plausible after carbon dioxide doubling.
I have been
intrigued at the media claims of "...up to 11 degrees..." temperature increase
from this http://www.climateprediction.net
Oxford Uni group which utilises tens of thousands of idle PC's worldwide
to run their climate model.
Apart from the fact that it is very difficult seeing exactly where
they get their 11 degrees from, I can only see a max increase of ~8 degrees
in Fig 1 of their Jan 05 Letter to Nature which is easily downloadable off
their website. As is their 26 January 2005 Press Release.
Their Fig 2
a, a histogram shows that only a tiny proportion of runs produce a
result ~11 degrees. The vast majority of models predict only a ~3.5
degree rise after the 15 year run post instant CO2 doubling.
It must be a worry for their future work out to 2100 that most of that
3.5 degree rise is in the first 5 years, then T shows little change out
to the 15 years.
walk through some of their web pages.
Starting at the http://www.climateprediction.net
Follow their Climate Science link at left, look down for link to page
setting out their "Experiment strategy - the basics"; We see this
Table setting out their grand strategy. As far as I can find they are yet
to tell anything of Experiments 2 and 3.
results are seen on their Graphs as 1810 to 1825, the Pre-industrial
CO2 run (sometimes termed Control)
is from 1825 to 1844, the Double CO2
run is from 2051 to 2065. Note that for this run CO2
is doubled instantly to 550 ppm. Why not input annual incremrents as in
the real world ?? Now scroll below the table for some early results.
Strategy Table from
Explore model sensitivity to parameters
[tell me more]
Identify suitable ranges of parameters.
Each simulation includes 3 phases:
- Calibration (15yrs)
- Pre-industrial CO2 run (15yrs)
- Double CO2 run (15yrs)
Simulation of 1950-2000
[tell me more]
Assess model skill by making a probability based forecast
of the past climate.
Run the model with a range of initial conditions and parameters for the period 1950-2000.
Compare model outputs with observations to assess how well the model
Simulation of 2000-2100
[tell me more]
Make a probability based forecast of future climate.
Run the model with a range of initial conditions, forcings and parameters for the period 2000-2100.
We look at some results from their first
5000 runs at http://www.climateprediction.net/science/firstresults.php
A stable, "normal" run. Most of the runs we are
getting back at the moment look fairly similar to this 74958 Click
on graph for large screen copy. The blue line is the 1810 to 1825 phase.
The green line 1825 to 1840 is the control phase. The red line
is the 2050 to 2065 doubled CO2 phase.
A warm, wet outlier. 91249 is an example of a stable experiment
that went warmer and wetter than most in the doubled carbon dioxide phase.
Coolwire wants to point out here the Climateprediction.net use
of approving words such as "stable" and "normal" for the result that
indicated a temperature rise of circa 3 degrees C. Note not 11
Note the use of the word "outlier" for the result that indicated a temperature
rise of circa 8.5 degrees C. Note still not 11 degrees C
At http://climateapps2.oucs.ox.ac.uk/cpdnboinc/projstat.html Climateprediction.net
post the latest 10 runs coming into their server. You can click through
these (and you will strain to find any 11 degress increases). To help readers
quickly review many recent Climateprediction.net model runs Coolwire is
collecting the results whenever time allows and you can see a web
page full of thumbnail graphs, which if clicked on show you the full size
Climateprediction.net model run result.
Now consider the Climateprediction.net Press Release of 26 January 2005
headlined "Bleak first results....." which says, "...average
temperatures could eventually rise by up to 11°C..." and makes
no mention of any other temperature. Why did not Climateprediction.net
tell the press, "We are only telling you here about a minor percentage
of results which between ourselves we term outliers. We are
not mentioning in this Press Release that the vast majority of our results
(which we term stable and "normal") indicated a temperature rise
of 3°C, not nearly as sexy as 11°C.
As we all know (and Climateprediction.net knows), the press are more
likely to run a Global Warming story claiming an 11°C
increase than one claiming a pifling 3°C rise.
It is also interesting that after the Hollywood climate change disaster
epic "The day after tomorrow" came out last year, this was of sufficient
scientific interest to Climateprediction.net that they immediately
threw aside their published Strategy (see above Table)which sets out the
order of their Experiments. They rushed into a Phase 4 experiment which assumed
the thermohaline circulation slowed in 2064, results in yellow on graph at
left are from. Follow their project News links for their news archive.
AND, note that this graph in fact shows only a tiny handful of runs
plus 8°C.(you can count them ), showing how tenuous any claim
is promoting an ~11°C rise.
Finally, Coolwire notes that Climateprediction.net have published NO
results replicating the 1950-2000 period.
They say at http://www.climateprediction.net/science/strategy.php
Experiment 2 (Simulation of 1950-2000)
"By using each model to produce a 'forecast' for 1950-2000, and then
comparing the spread of forecasts with what actually happened, we will get
an idea of how good our range of models is - do most of them do a good job
of replicating what actually happened? This will also let us 'rank' models
according to how well they do."
[Note: To be launched in 2005.] Coolwire says, "sounds fine, lets
see some results."
Under Experiment 3 (Simulation of 2000-2100) they say, "When
this experiment finishes, we will have a range of forecasts for 21st century
climate. The final stage is to 'weight' the forecast of each model according
to its ranking in experiment 2 - so, for example, if a model that did really
well in experiment 2 predicts a warming of 2 degrees, and one that did badly
in experiment 2 predicts a warming of 10 degrees, we will believe the first
one more than the second."
Once again Coolwire has to say, "this sounds fine but the propositions
are at odds with the tenor of their Letter to Nature and their sensationalist
26 Jan '05 Press release.
All in all, Coolwire thinks that illustrious Oxford scholars would
be turning in their graves.
Back to http://www.warwickhughes.com/climate/
Back to http://www.warwickhughes.com/