JoNova (Australia)
There was a time back in 1933 when
the CSIRO was called CSIR and meteorologists figured that with 74 years
of weather data on Australia, they really ought to publish a serious
document collating all the monthly averages at hundreds of weather
stations around Australia. Little did they know that years later,
despite their best efforts, much of the same data would be forgotten and
unused or would be adjusted, decades after the fact, and sometimes by
as much as one or two degrees. Twenty years later The Commonwealth
Bureau of Census and Statistics would publish an Official Year Book of
Australia which included the mean temperature readings from 1911 to 1940
at 44 locations.
Chris Gillham has spent months
poring over both these historic datasets, as well as the BoM’s Climate
Data Online (CDO) which has the recent temperatures at these old
stations. He also compares these old records to the new versions in the
BOM’s all new, all marvelous, best quality ACORN dataset. He has
published all the results and tables comparing CDO, CSIR and Year Book versions. He analyzes them in many ways –
sometimes by looking at small subsets or large groups of the 226 CSIR
stations. But it doesn’t much matter which way the data is grouped, the
results always show that the historic records had warmer average
temperatures before they were adjusted and put into the modern ACORN
dataset. The adjustments cool historic averages by around 0.4 degrees,
which sounds small, but the entire extent of a century of warming is
only 0.9 degrees C. So the adjustments themselves are the source of almost half of the warming trend."
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