Date: 01/19/2005

Name: Hans
Subject: Re: Someone's state of ignorance

Message: Hi Dano,
Have a look at this graph:

Up to 2030 it doesn't matter much which scenario we follow, they ALL get hotter. After 2030 the big increase is from developing countries like China and India, who just decided in Buenos Aires that they don't intend to limit their output.

So let's wait 30 years to see what really materialises from the above scenario, like the Club of Rome forecasts.



 

Date: 01/19/2005

Name: Đano
Subject: Re: Re: Someone's state of ignorance

Message: .

Thanks for the linky Hans.

As you know, the WG1 conclusions are from 2001. Are there any newer results for model suites since then?


Best,

ĐanŘ



 

Date: 01/20/2005

Name: Hans
Subject: The model appraisal

Message: LOL talking of ploppedness, dumping a 197 page document could you indicate which pages you consider the most relevant?



Cloud cover is still very badly modeled in both polar regions (fig 4.11, page 50),
indicating that moisture transport to the poles is poorly understood
. Same for sea level pressure.
Remember: the poles are the canary in the coalmine.


Quotes from the Appraisal Summary:


All of the coupled models exhibit a “split” intertropical convergence zone (ITCZ) in the Pacific Ocean.
This typically occurs in conjunction with a westward extension of the equatorial cold tongue and too-strong
easterlies that extend into the western Pacific. Comparison with AMIP integrations indicates that the “split”
ITCZ is also apparent, even when observed SST was prescribed as the surface boundary condition.
This suggests that air-sea interaction may not be the root cause of the “split” ITCZ, but rather has exacerbated
a pre-existing shortcoming in the atmospheric models. Systematic error in the coupled model is also present
in the Atlantic basin, with the Southern Hemisphere anticyclone being too weak.



difficulties remain in the simulation of ENSO (e.g., amplitude, seasonality, and periodicity),



Tropical wave spectra further confirm the difficulty the models have in representing tropical interactions.
The models have difficulty in generating the observed level of variability as a function of space and time scale.
This is particularly apparent for synoptic timescales (2-6 days) and higher-order wave numbers (5-15).



The North Atlantic Oscillation is well represented by the appraisal models. The spatial
pattern of the large-scale surface air temperature response to the sea-level pressure
perturbation over the Atlantic is akin to that observed, with
the spatial error indicating the model response was not as strong as observed.
This shortcoming was systematic across the models analyzed,



The discrepancy among models and the Levitus climatolgies are most prevalent in the Arctic Basin.



Now this document gives a nice summary of the state of the models, lets see what's improved in five years time.

Don't worry the world will still be there....



 

Date: 01/21/2005

Name: Hans
Subject: Model appraisal 2

Message: Firstly looking at the 1% CO2 increase response graph on page 29:
Up to a factor of 1.3 (500 ppm) after 30 years, there is still a lot of noise in the models, the temperature increase is then between 0 and 1.3 degrees Celsius.

At the CO2 doubling time (after 70 years from start), I quote from page 28:


The main difference from the CMIP2 results is the addition of one or two new models that obtain global mean warming at the high end: ~3 K after 80 years of CO2 increase. Still, the general results shown here are consistent with both the CMIP2 overview and many other studies over the years (e.g., Fig. 9.3 in Cubasch et al. 2001). Global mean warming at the time of CO2 doubling is in the range 1–3 K


I.e. Model Climate sensitivity is 1 to 3 K for CO2 doubling.

In other words we still have plenty time (at least 30 years if CO2 were to rise by 1%, but really - as the CO2 rise is not that fast - until the atmospheric CO2 level reaches 500 ppm to validate which model climate sensitivity is corresponding to real world climate sensitivity.



My messages edited for typos, see TechCentralStation for the original messages