The Bureau of Meteorology [BOM] has released its report for Australian climate during 2013. According to the BOM 2013 was the hottest year on record, in Australia. However both satellite temperatures, RSS and UAH, and a global surface temperature, GHCN, all found other Australian years to be warmer:
Naturally the pro-AGW people have been all over the BOM report claiming it as evidence for AGW, while ignoring the results from the other equally valid sources for temperature. But even if the BOM report is correct it is problematic whether AGW is the cause of the temperature. It is doubtful because during 2013 and for at least a decade the Diurnal Temperature Range [DTR] has not been decreasing but increasing.
The DTR is the difference between the maximum and minimum temperatures. AGW theory predicts that the minimum temperatures should increase more than maximum temperatures and the DTR should decrease. This is explained by the IPCC at Figure 3.2 of their 4th report, AR4. AR4 gives a variety of reasons why the DTR should decrease but the main one is that back-radiation, which is the radiation the extra CO2 in the air throws back towards the Earth, will have a more pronounced effect at night.
Given this a simple test of whether the hottest year in Australia was due to AGW would be to measure the DTR. Ken Stewart has done this:
Since 1979 it is plain the gap between the maximum and minimum temperature has increased. So, in fact the DTR in Australia has increased not decreased.
Still, there is no doubt 2013 was a relatively warm year for Australia. It was certainly warmer than the year in the Antarctic. Professor Chris Turney and team of fellow scientists and media, and as it turns out family members, hired a ship apparently at taxpayers' expense and sailed to the Antarctic to retrace Mawson's steps from 100 years ago.
There is a certain irony in an expert climate scientist being trapped in sea ice. Despite this Professor Turney and his supporters such as the well-known Professor Lewandowsky have maintained the sea ice which trapped Professor Turney's boat, the Akademik Shokalskiy, was due to AGW.
The 120km long ice berg B09B that is grounded in Commonwealth Bay broke away from the continent three years ago, very likely as a result of climate change.
B09B collided with the Mertz Glacier, smashing a large ice tongue that released the ice into that area.
It was a mix of this ice that was blown across the path of the Shokalskiy, which led to it being trapped and explains why much of the ice surrounding the ship is old ice.
All of this incorrect. As the Australian Antarctic Division notes:
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