One hundred years of drought and flooding rains

It is ridiculous to say that reduced soil moisture “is very likely”. We have really very little idea, since we don’t know what the rainfall will be, the trend in evaporative demand has recently been downward in Australia ... and in New Zealand [references cited], and we don’t know what the demand will be in the future, and stomatal conductance is reduced at higher [CO2] (Comment 11-549).

To which the Australian co-ordinating lead author of the chapter, Kevin Hennessy of CSIRO, responded:

Change in PET [potential evapotranspiration] has also been quantified for Australia and NZ. Will consult David Jones (BoM).

There were equally dismissive responses to some of Graham Farquhar’s other comments. Hennessy’s reply to the comment that “We think that on average rainfall will increase (averaged globally), but we have little power to predict regionally what will happen in detail” (Comment 11-207) was “Disagree. The climate models that indicate an increase in global average rainfall and evaporation also provide regional information.”

Here Kevin Hennessy was not only disagreeing with Graham Farquhar but also with Dr John Zillman, who said in his World Meteorological Day Address in 2003 that he believed that the question of how global warming could “be manifest at the national, regional and local level” was presently “completely unanswerable”.

At the time that he gave this address, Zillman had been Chief Delegate for Australia to the IPCC for eight years, President of the World Meteorological Organization for the same period and Australia’s Director of Meteorology for 25 years. He has been a prolific contributor to the work of the IPCC and is the author of 130 scientific papers.

The Bureau of Meteorology now claims to have answers to the questions that its then-Director held to be “completely unanswerable” only five years ago. The Bureau’s logo, as well as that of CSIRO, appears on the Drought Exceptional Circumstances Report in which it is stated that “the frequency and areal extent of ... exceptionally low moisture years are likely to increase in the future”, not just in Australia as a whole but in all of the seven regions distinguished in the report (pps. 23-29).

I discussed the CSIRO/Bureau of Meteorology report and David Stockwell’s critique in my previous article for On Line Opinion. It is still my hope that the authors of the report will defend their work, as good scientists should.