The BOM claim their adjustments are random and neutral. Yet when Ken looked at the raw data from Australia’s 100 high quality rural sites, the adjustments increased the trend in the raw data by 40% — from a 0.6°C rise over 100 years, to 0.85°C over 100 years.
In an email to Ken, Dr David Jones, Head of Climate Monitoring and Prediction, National Climate Centre, Bureau of Meteorology, made a clear claim that the adjustments had no real effect:
“On the issue of adjustments you find that these have a near zero impact on the all Australian temperature because these tend to be equally positive and negative across the network (as would be expected given they are adjustments for random station changes).”
Perhaps there are good reasons for all these corrections. But if Ken’s analysis is right, the adjustments themselves account for a third of the reported warming trend in Australia.