Remember how the New Zealand Climate Science Coalition made the warming trend in New Zealand go away by treating measurements from different sites as if they came from the same site? Well, Willis Eschenbach has followed in their foot steps by using the same scam on Australian data. He claims that for Darwin “the trend has been artificially increased to give a false warming where the raw data shows cooling”. Here’s his graph:
That blue line for raw temperature in his graph combines different records without any adjustment, even though Eschenbach could see that there was a step change between record 0 and record 1.
The adjustment procedure used is described here, with the the authors noting:
A great deal of effort went into the homogeneity adjustments. Yet the
effects of the homogeneity adjustments on global average temperature
trends are minor (Easterling and Peterson 1995b). However, on scales
of half a continent or smaller, the homogeneity adjustments can have
an impact. On an individual time series, the effects of the
adjustments can be enormous. These adjustments are the best we could
do given the paucity of historical station history metadata on a
global scale. But using an approach based on a reference series
created from surrounding stations means that the adjusted station’s
data is more indicative of regional climate change and less
representative of local microclimatic change than an individual
station not needing adjustments.
Eschenbach, however, simply declares the NOAA’s adjustments “blatantly bogus” that created a “false warming”. This isn’t a strong argument, but maybe there is a way to check the NOAA’s work?
Oh look, here’s the Australian Bureau of Meteorology’s high quality climate data for Darwin aiport
Their notes state:
A change in the type of thermometer shelter used at many Australian observation sites in the early 20th century resulted in a sudden drop in recorded temperatures which is entirely spurious. It is for this reason that these early data are currently not used for monitoring climate change. Other common changes at Australian sites over time include location moves, construction of buildings or growth of vegetation around the observation site and, more recently, the introduction of Automatic Weather Stations.
The impacts of these changes on the data are often comparable in size to real climate variations, so they need to be removed before long-term trends are investigated. Procedures to identify and adjust for non-climatic changes in historical climate data generally involve a combination of:
- investigating historical information (metadata) about the observation site,
- using statistical tests to compare records from nearby locations, and
- using comparison data recorded simultaneously at old and new locations, or with old and new instrument types.
And full details of the procedure are described in this paper.
I suppose the next argument is that the NOAA and the BOM are conspiring together to falsify the temperature record.
Eschenbach, by the way, has cooked temperature records before.