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The Forum > Article Comments > The measure that matters > Comments

The measure that matters : Comments

By John Le Mesurier, published 29/10/2010

Focussing on per capita emissions of CO2 will lead to increasing emissions, not decreasing.

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Bonmot, there is not much point posting links if they have little to do with your argument. The first couple provide a definition of radiative forcing. I don't think that was at issue.

The second two hilariously try to work out the radiative forcing of gases other than CO2 by using models. But the models paramaterise the forcings in the first place, which means they pick a figure they think is probably right and use it to amplify the CO2 (warming which we can calculate because the physics is well understood). Which means they are basically assuming the thing that they try to prove.

Agnostic, it is well accepted that CO2's reaction to heat is logarithmic. If we need a scientific citation before that is accepted, we are going to need citations to prove that the sun rises in the east, that massive objects exert a force on other massive objects inversely proportional to the distance between them (actually there is a paper for that, but I'm not sure that it is peer reviewed) etc. It's not a novel claim that I've made, it's well-accepted scientific fact.

It says something about the misdirection in the whole debate that so few people seem to be awarea of what the real argument is about.
Posted by GrahamY, Friday, 5 November 2010 8:09:40 PM
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Raredog

You claim that there is ... “a marked decline in its (CO2’s) warming effect between 50ppm and around 200ppm – representing about 4°K increase; beyond around 200ppm to well over 800ppm the warming effect declines to about 1°K or less”.

In other words the logarithmic effect of CO2 concentration on temperature is such that the first (50-200ppm) is four times greater than the second (200->800ppm).

Wrong. A logarithmic response means that the warming for increase in CO2 from 50 to 200 (a quadrupling) will be the same as from 200 to 800 (also a quadrupling). It does not mean that the first will be four times the second. I repeat, Logarithms do not behave the way you describe.
Posted by Agnostic of Mittagong, Saturday, 6 November 2010 1:34:51 PM
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No Graham. It is patently obvious that some people don’t understand the relationship between radiative forcing, temperature change and GHG concentrations. And some, Graham, appear to be deliberately obtuse in their comments or 'opinion'. Whether they do this in ignorance or by deliberate/malicious spread of FUD does not really matter, the damage is done.

For example, you said to me;

“You're the only one who thinks that regional forecasts are any good. The IPCC warns against them, and their unreliability is also noted in the latest Royal Society statement on climate change.”

Graham, you are deliberately distorting and misrepresenting what I said – which was;

“The IPCC’s AR5 should make it clearer as to what different regions should expect – increased data and computing technology will enable this,” and

“there is much more data now than in AR4 and the computational power that is being accessed for AR5 is much greater. The resolution will be much starker and regional projections will be achievable. Whether you accept this or not is of no consequence.”

Most people would see the difference. However, I will try and make it clearer for you.

Regional climate projections since AR4 will improve because of more data and more advanced computing power. Here in Australia the CSIRO, BOM and the Departments of Climate Change; Sustainability, Environment, Water, Population and Communities; Agriculture, Fisheries and Forestry, and so on (federal, state, local) including major industry and private stakeholders are encouraged by these recent developments. I should not have to explain why.
Posted by bonmot, Sunday, 7 November 2010 11:57:01 AM
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AoM

I am sure Raredog understands and if I may (he will correct me if I’m wrong, I hope) will re-phrase what he has said (in part).

i.e. To achieve the same temperature “change” at higher CO2 concentrations requires more CO2 than previous.

For example, given IPCC 'climate sensitivity' (lambda) = 3 degrees:

A “3 degrees temperature change” requires a doubling from 280 ppmv to 560 ppmv.

A *same* “3 degrees temperature change” requires also a doubling from 560 ppmv to 1120 ppmv.

In other words, only 280 ppmv is required for the initial 3 degrees “change,” while 560 ppmv is required for the next 3 degrees “change”.

The “change in temperature” is proportional to the “change in radiative forcing” (1st order approximation) and GHG’s are a significant radiative forcing. The fact that Graham thinks this does not contribute to some or other “argument,” or the models are “hilarious,” is simply astounding – expected on an open forum I suppose, but from the site owner?

Anyway, look at the graph top of page 2717 in Myhre et al http://folk.uio.no/gunnarmy/paper/myhre_grl98.pdf

The slope (gradient) of the log function at current atmospheric [CO2] levels is quite steep ... and it is still quite steep at 600 ppmv. Indeed, the concentration of CO2 will have to be very much higher before the slope approaches the horizontal asymptote – extrapolated in the order of 5,000 ppmv. This is extremely high and life as we know it would not exist. But you are right, it will be bad enough at 720 ppmv.
Posted by bonmot, Sunday, 7 November 2010 12:08:55 PM
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"For example, given IPCC 'climate sensitivity' (lambda) = 3 degrees"

should read;

For example, given IPCC 'climate sensitivity' (lambda) = 5.35
Posted by bonmot, Sunday, 7 November 2010 12:16:30 PM
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Please disregard my last 2 comments (now had a strong coffee).

Best see http://en.wikipedia.org/wiki/Radiative_forcing

You can see the values for 'climate sensitivity' and the log function there.
Posted by bonmot, Sunday, 7 November 2010 3:10:18 PM
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