måndag 30 september 2013
Thomas Stocker's Defense of IPCC Climate Models at Variance with Observations
Global temperature increased according to observations in the periods 1920 - 40 and 1978 - 1996 with about 0.35 C, while the temperature was slightly decreasing in the periods 1880 - 1920, 1940 - 1978, 1997 - 2013.
The main argument used by IPCC co-chairman Thomas Stocker when defending the climate models of IPCC AR5 predicting steady warming, was that the 17 year period 1997 - 2013 with no warming was too short to allow any conclusion that CO2 forcing was too small to be observed, while the 18 year period 1978 - 1996 with warming was long enough be able to attribute with 95% likelihood the warming to CO2 forcing. Stocker clarified the argument by adding that a period of 30 years would be required to be able to detect a trend in global cooling.
PS1 The temperature curves for the periods 1920 - 1950 and 1973 - 2013 are very similar with first warming and then slight cooling, only shifted with a steady rise of about 0.5 C/century after the Little Ice Age. The rise 1920 - 1940 is not attributed to CO2 by IPCC while the rise 1976 - 1996 is. The logic is missing.
PS2 The above graph produced by IPCC appears to present lower than actual temperatures before 1960 thus enhancing the warming thereafter.