Andrew Bolt of the Herald Sun digs up another issue with non peer reviewed World Wildlife Fund reports in the IPCC AR4. It turns out a new paper in GRL handily disputes the cause of the drought.
Melbourne University alarmist David Karoly once claimed a rise in the Murray Darling Basin’s temperatures was “likely due to the increase in greenhouse gases in the atmosphere from human acitivity” and:
This is the first drought in Australia where the impact of human-induced global warming can be clearly observed.
Prime Minister Kevin Rudd grabbed the scare and exploited it:
BRENDAN Nelson was yesterday accused of being “blissfully immune” to the effects of climate change after he said the crisis in the Murray-Darling Basin was not linked to global warming…
In parliament yesterday, Kevin Rudd attacked Dr Nelson, accusing him of ignoring scientific facts.
“You need to get with the science on this,” the Prime Minister said. “Look at the technical report put together by the CSIRO and the Bureau of Meteorology.”
But the latest evidence shows that Rudd and Karoly were wrong. In fact, there’s no evidence in the Murray Darling drought of man-made warming, says a new study in Geophysical Research Letters, this new study:
Previous studies of the recent drought in the Murray-Darling Basin (MDB) have noted that low rainfall totals have been accompanied by anomalously high air temperatures. Subsequent studies have interpreted an identified trend in the residual timeseries of non-rainfall related temperature variability as a signal of anthropogenic change, further speculating that increased air temperature has exacerbated the drought through increasing evapotranspiration rates. In this study, we explore an alternative explanation of the recent increases in air temperature. This study demonstrates that significant misunderstanding of known processes of land surface – atmosphere interactions has led to the incorrect attribution of the causes of the anomalous temperatures, as well as significant misunderstanding of their impact on evaporation within the Murray-Darling Basin…
However, to accept the correlation [between temperature and rainfall] as the sole basis for the attribution of cause to human emissions is to implicitly assume that the correlation represents an entirely correct model of the sole driver of maximum air temperature. This is clearly not the case.
What’s causing the evaporation and temperatures is not (man-made) warming. It’s kind of the other way around: more sunshine, through lack of cloud cover, and lack of rain and therefore evaporation is causing higher temperatures.
Reader Baa Humbug:
Karoly was cited very extensively in the AR4 WG1 paper.e.g. Chapter 9 220.127.116.11 Studies Based on Indices of Temperature Change and Temperature-Precipitation Relationships.”Studies based on indices of temperature change support the robust detection of human influence on continental-scale land areas. Observed trends in indices of North American continental scale temperature change, (including the regional mean, the mean land-ocean temperature contrast and the annual cycle) were found by Karoly et al. (2003) to be generally consistent with simulated trends under historical forcing from greenhouse gases and sulphate aerosols during the second half of the 20th century. In contrast, they find only a small likelihood of agreement with trends driven by natural forcing only during this period .