date: Tue Jul 5 10:15:39 2005 from: Phil Jones subject: FW: Your graph regarding global temperature anomaly to: heino.schmid@aon.at Dear Heinrich, There are a multitude of explanations of the course of temperature change during the 20th century. These are discussed in the various IPCC reports. The warming from 1915 to about 1940 is generally believed to be due to a slight increase in solar output and a reduction in volcanism. The recent warming from 1975 is due to the build-up of greenhouse gases, as they begin to dominate over sulphate aerosol releases. The slight cooling from 1940 to 1975 is thought to be due to industrial development (using lots of dirty coal) increasing aerosol emissions. WWII is not thought to have had any impact. On all the above there is natural variability which could have caused some of the changes even without any external forcing (greenhouse gases, aerosols, solar, volcanoes etc) as we have had warm and cold decades in the past when there was little changes in external influences. I hope this short reply helps. The best things to read are the IPCC reports. Regards Phil -----Original Message----- From: Heinrich Schmid [[1]mailto:heino.schmid@aon.at] Sent: Sunday, June 26, 2005 8:35 AM To: cru@uea.ac.uk Subject: Your graph regarding global temperature anomaly Sir, viewing the graph one recognizes a significant change in direction at about the year 1910. Then there is another change at about 1940 and again at about 1975. This period between 1940 and 1975 could be interpreted as being due to the negative forcing of the dust and smoke created during WWII. Your response would be appreciated. This interpretation would have significant implications to our understanding of global warming Sincerely Heinrich Schmid Kellertal 171 A-6410 Pettnau Austria Prof. Phil Jones Climatic Research Unit Telephone +44 (0) 1603 592090 School of Environmental Sciences Fax +44 (0) 1603 507784 University of East Anglia Norwich Email p.jones@uea.ac.uk NR4 7TJ UK ----------------------------------------------------------------------------