Richard C. Courtney's comment

[Sunsettommy]

From HERE

Quote:Richard S Courtney says:
August 21, 2011 at 4:13 am

Girma:

You understate your case when at August 21, 2011 at 3:27 am you say;

“However, the IPCC says there is further warming of 0.2 deg C per decade in the next two decades.
Is that rational?
How could something that has not happened in the last 160 years going to happen in the next twenty years?”

The only prediction (i.e. not “projection”) of the IPCC is much more wong than you say.

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...s10-7.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.

A RISE OF 0.2°C OVER THE LAST 10 YEARS WOULD HAVE BEEN OBVIOUS FROM THE DATA.

So, for the IPCC prediction to be true then the global temperature must rise by a staggering 0.4°C now and stay at that 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 over the next 10 years is at least an incredible 0.24°C.

And to meet the IPCC prediction at a linear rate then the required rise over the next ten years is 0.8°C (or 0.48°C at very minimum).

Richard