Mathematics, BoM-style

2+2Jen Marohasy helps Environment Minister Bob Baldwin settle into his new post with some sound advice on the Bureau of Meteorology, its peculiar habit of tickling temperature records and the remarkable result: every year, without fail, is allegedly warmer than all the scorchers that went before:

1. Use the same locations when calculating the average mean temperature for different years.  Adding hot stations later, generates its own artificial warming bias.

2. Start the official record from 1880, not 1910, thus including the hot years of the Federation drought (1895-1903).   To suggest this is impossible because there were no Stevenson screens before 1910 is inconsistent with the historical record, which shows there were even Stevenson screens installed a locations in Western Australia from 1880.

3.  Don’t homogenize individual temperature series, changing actual recorded temperatures, unless there was a documented equipment change or site move.  It is nonsense to change the magnitude and direction of temperature trends based on statistical discontinuities with locations in different climatic zones.   Indeed, this was the original justification for changing an overall cooling trend of 0.35 degree per century, to a warming trend of 1.73 degree per Century, at the Rutherglen Research Station in north east Victoria.

Marohasy’s letter can be read in full via the link below.

 

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