PrintFebruary 8, 2010
Droughtgate: Study Finds IPCC had Temperature - Drought Connection Backwards
Add another to the growing list of IPCC outrages.
As I mentioned in last week’s IPCC: International Pack of Climate Crooks, in Chapter 9 of Assessment Report 4’s (AR4) Working Group One (WG1) Report, the IPCC claimed that manmade CO2-driven higher temperatures drive higher evaporation, and thereby cause droughts. As readers are all too aware, droughts are favorite ingredients in most alarmists’ recipes for manmade climate disaster. But a paper published last month in Geophysical Research Letters lays out a compelling argument that the IPCC has it completely backwards – that droughts are actually causing warming, not the other way around.
In Section 9.1.2, the IPCC states that: [emphasis mine throughout]
[P]recipitation and temperature are ordinarily inversely correlated in some regions, with increases in temperature corresponding to drying conditions. Thus, a warming trend in such a region that is not associated with rainfall change may indicate an external influence on the climate of that region (Nicholls et al., 2005; Section 9.4.2.3).
That statement is attributed to the same Neville Nicholls who wrote in his 2004 paper, The Changing Nature of Australian Droughts, that:
The relatively warm temperatures in 2002 were partly the result of a continued warming evident in Australia since the middle of the 20th century. The possibility that the enhanced greenhouse effect is increasing the severity of Australian droughts, by raising temperatures and hence increasing evaporation, even if the rainfall does not decrease, needs to be considered.
Later in the paper, Nicholls concluded that “the warming has meant that the severity and impacts of the most recent drought have been exacerbated by enhanced evaporation and evapotranspiration.”
Not surprisingly, as with many other AR4 irregularities that have recently surfaced, this too has a non-peer-reviewed World Wildlife Fund link to it. Nicholls’ was an extension of the work of fellow Aussie alarmist, David Karoly, whose 2003 WWF report, Global warming contributes to Australia's worst drought [PDF], studied the 2002 drought in Australia’s Murray-Darling Basin and found that:
"This drought has had a more severe impact than any other drought since at least 1950, because the temperatures in 2002 have also been significantly higher than in other drought years (see Table 1 and 2). The higher temperatures caused a marked increase in evaporation rates, which sped up the loss of soil moisture and the drying of vegetation and watercourses. This is the first drought in Australia where the impact of human-induced global warming can be clearly observed."
So then, the basis for the claim that anthropogenic warming causes droughts put forth in the IPCC’s AR4 was a WWF report and its follow-up written the next year.
But that basis, conclude Natalie Lockart, Dmitri Kavetski and Stewart W. Franks, authors of On the recent warming in the Murray-Darling Basin: Land surface interactions misunderstood, is bogus. As stated in its opening, their 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.” And after deconstructing the claims of both Nicholls and Karoly, concludes that:
All presented results demonstrate that potential evaporation under dry conditions is elevated not as a result of the air temperature, but as a result of the lack of actual evaporation. This is accompanied by increased sensible heat fluxes which increases air temperatures. This is an entirely natural consequence of the dynamics of drought. Importantly, it is shown that antecedent temperature increases do not lead to significant increases in actual or potential evapotranspiration.
As coauthor Stewart Franks explained to me in an email, “this is a confusion of the well known physics of evaporation - as higher air temperatures are driven by the lack of evaporation (as occurs during drought).” He explained further in a subsequent correspondence:
Of course, when there is a deficit of rainfall, this tends to be accompanied by less cloud-cover, hence more sunshine, which does increase the energy available for evaporation, but as soil moisture is low, the bulk of the energy goes into heating the near-surface atmosphere and hence higher air temperatures.
But amazingly, the story doesn’t end with how wrong the chapter was.
Professor Franks also pointed out that Neville Nicholls was one of the chapter’s Lead Authors, and David Karoly, whose work was also heavily cited in WG1 Chapter 9, was its Review Editor.
Quipped Franks: “Hence they cite and review their own papers as part of the clearly flawed IPCC process.”
Unbelievable.
