Old prediction may fit the present pattern

Bob B:
At June 1, 2011 at 6:15 am you write and ask:
“A little off topic, but I would ask for help here. My sister is in the middle of a fight with a school principle who just had an eco-group do a school-wide presentation on global warming and told all the kids to reduce their carbon footprints and tell their parents to do so. I told my sister to tell the principle the school need to teach the kids critical thinking and some one needs to ask how much the mean global surface temperature will be reduced by their efforts? I told her to tell them it would be ZERO. But I am looking for someone who might have done some basic calcualtions to prove just that.”
The appropriate answer is to point out that the IPCC has admitted that nobody knows what the effect would be but it is probably zero.
Chapter 2 of the report by IPCC Working Group III the IPCC in the IPCC Third Assessment Report (TAR) says;
“Most generally, it is clear that mitigation scenarios and mitigation policies are strongly related to their baseline scenarios, but no systematic analysis has published on the relationship between mitigation and baseline scenarios.”
This statement is in the middle of the Chapter and is not included in the Chapter’s Conclusions. Failure to list this statement as a conclusion is strange because this statement is an admission that the assessed models do not provide useful predictions of effects of mitigation policies. How could the predictions be useful if the relationship between mitigation and baseline is not known?
Also, the only valid baseline scenario is an extrapolation from current trends. The effect of an assumed change from current practice cannot be known if there is no known systematic relationship between mitigation and baseline scenario. But each of the scenarios is a claimed effect of changes from current practice. So, the TAR itself says the scenarios are meaningless gobbledygook.
But then one needs to assess the underlying assumption of the cause of the putative warming which the mitigation scenarios are claimed to address.
The underlying assumption of the IPCC scenarios is that “committed warming” results from energy being stored in the oceans. This energy gets released to the atmosphere in later decades and induces the “committed warming”. So, the total warming increases at a higher than linear rate with time as both “committed warming” and ‘instant’ warming increase.
Therefore, initiation of a mitigation has no discernible effect for some time. The mitigation reduces the relatively small ‘instant’ warming and reduces the energy going into the storage in the oceans but does not alter the “committed warming”.
Then, as decades pass, the ‘instant’ warming continues to be reduced and – importantly – the reduced input to the store of energy in the oceans reduces the “committed warming” and so the mitigation becomes discernible.
However, this “committed warming” seems to have vanished (Trenberth says this is a “travesty”).
Section 10.7.1 titled ‘Climate Change Commitment to Year 2300 Based on AOGCMs’
in the Report from WG1 (i.e. the “science” Working Group) of the most recent IPCC Report (AR4) can be read at
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-7.html
It says:
“The multi-model average warming for all radiative forcing agents held constant at year 2000 (reported earlier for several of the models by Meehl et al., 2005c), is about 0.6°C for the period 2090 to 2099 relative to the 1980 to 1999 reference period. This is roughly the magnitude of warming simulated in the 20th century. Applying the same uncertainty assessment as for the SRES scenarios in Fig. 10.29 (–40 to +60%), the likely uncertainty range is 0.3°C to 0.9°C. Hansen et al. (2005a) calculate the current energy imbalance of the Earth to be 0.85 W m–2, implying that the unrealised global warming is about 0.6°C without any further increase in radiative forcing. The committed warming trend values show a rate of warming averaged over the first two decades of the 21st century of about 0.1°C per decade, due mainly to the slow response of the oceans. About twice as much warming (0.2°C per decade) would be expected if emissions are within the range of the SRES scenarios.”
So, the IPCC says “The committed warming trend values show a rate of warming averaged over the first two decades of the 21st century of about 0.1°C per decade”.
n.b. That is “committed warming” that will occur because of effects in the past.
And the effect of increase to atmospheric CO2 since 2000 is expected to double that rate of warming to “About twice as much warming (0.2°C per decade)”.
But there has NOT been a rise in global temperature of “0.2°C per decade” or of “0.1°C per decade” for the first of half of “the first two decades of the 21st century”. Indeed, there has been no discernible rise and probably a slight fall.
So, for the IPCC prediction to be true then the global temperature must rise by a staggering 0.4°C now and be sustained at that higher level for the next 10 years. This would be more than half the total rise over the previous century, and only a member of the cult of AGW could think this is a reasonable expectation.
Indeed, if one accepts the lower limit of the “uncertainty assessment” of “-40%” then the required immediate rise needed to be sustained for the next 10 years is at least an incredible 0.24°C.
And if the needed rise from now were linear it would need to increase global temperature by 0.8°C over the next 10 years (or at minimum by 0.46°C).
Nobody really thinks such rises are likely.
In summary, the claimed effects of ‘mitigation policies’ , ‘carbon footprints’, etc. are completely meaningless and should be disregarded. It is much better to look at the observed climate cycles and to see what range of climate effects they imply people should prepare for.
Richard

Richard S Courtney, “However, this “committed warming” seems to have vanished (Trenberth says this is a “travesty”).”
Not at all what Trenberth said. Just as with your misunderstand of what the IPCC said about a Tropospheric hotspot, you have this wrong. Your misunderstanding about the IPCC was pointed out numerous times to no avail, so there seems to be no reason to explain about Trenberth except to say you do not understand what he was talking about.