Thursday, July 22, 2010

Send in the clouds

ABC Environment online posted a brief article by reporter Graham Readfearn titled "Climate change and the role of clouds" on July 12. The article opens with the rather pithy statement "Clouds and water vapour play an important part in climate change, but the exact details of their role remains cloudy." Based on what follows perhaps ABC should have left it there.
In the ABC article Prof. Steven Sherwood, a professor of atmospheric physics at the University of New South Wales Climate Research Centre is quoted as saying: "We have quite a good understanding of water vapour. All our models say water vapour will increase by about seven per cent for every one degree of warming and we have observations to show that's happening."
We wondered which observations Prof. Sherwood was referring to, so we sent him an email. However Prof. Sherwood has not (yet) replied and given the ABC failed to do their job and ask which observations Prof Sherwood was referring to, we are left to speculate on their source. 
It's probably not the observations reported in a paper titled "Trends in middle - and upper-level tropospheric humidity from NCEP reanalysis data" by Garth Paltridge, Albert Arking and Michale Pook. This paper, published in the peer reviewed journal Theoretical and Applied Climatologyfinds that: 
First, the observations of relative humidity RH do not support the proposition that emerges from the behavior of general circulation climate models that the value of RH at any given height in the troposphere remains fairly constant under the influence of global warming (e.g., Soden and Held 2006; Pierrehumbert et al. 2007). 
Second, while the specific humidity q has increased at the lowest levels of the troposphere over the last three or four decades in concert with the surface and 1,000 hPa temperatures, it has decreased in the middle and upper levels. This is particularly obvious in the tropics, where the crossover to negative trends occurs somewhere about 850 hPa—roughly near the top of the convective boundary layer... These negative trends are not supported either by the predictions of climate models or by the few indications from satellite observations (e.g., Bates and Jackson 2001; Soden et al. 2005; Minschwaner and Dessler 2004) that the long-term trend of q in the upper troposphere is positive.
It seems these observations of water vapour don't support Prof. Sherwood, I guess he must be referring to something else.
Once again ABC's reliance on too few experts leaves it in the lurch. Perhaps the ABC could have asked Dr Roy Spencer for a comment? Or perhaps Prof Richard Lindzen?

ABC Reply 20/8/2010
Thank you for your email regarding the ABC Environment feature article 'Climate change and the role of clouds', published on 12 July. I understand you believe this article lacks balance.

I should explain that the article is categorised as topical and factual content for the purposes of the ABC's editorial standards. This content category is not subject to any requirement to achieve balance within individual programs or stories. However, it is subject to the impartiality requirement outlined in section 7.4.1 of the ABC's Editorial Policies (, as follows:

"The ABC is committed to impartiality: where topical and factual content deals with a matter of contention or public debate, a diversity of principal relevant perspectives should be demonstrated across a network or platform in an appropriate timeframe."

I understand the article was intended to canvas some of the current knowledge on the role of clouds and water vapour in climate change. ABC Innovation has advised that due to the incredible volume of scientific literature on climate science it was neither possible nor desirable to comprehensively cover all published articles and researchers in the field. However, the article cited four sources: Professor Steve Sherwood, Dr Rob Colman, research published in the journal Science, and research published in the Journal of Geophysical Research. It also made reference to two current research projects: the VAMOS Ocean-Cloud-Atmosphere-Land Study and the Silver Lining Project.

I note your comment that the article did not include the perspectives of Dr Roy Spencer or Professor Richard Lindzen. ABC Innovation has advised that they were not interviewed because, in contrast to Professor Sherwood and Dr Colman, they are not cloud and water vapour specialists based in Australia.

Audience & Consumer Affairs has reviewed the article, considered the perspectives it presented, and considered the range of other content on climate change and cloud science published on ABC Online. On review, we are satisfied that a diversity of perspectives has been demonstrated across the platform over time, in accordance with the requirements of section 7.4.1 of the Editorial Policies.

I note your comments about Professor Sherwood's reference to observations showing that water vapour is increasing by about 7% for every degree of warming. ABC Innovation has drawn attention to the paper 'Identification of human-induced changes in atmospheric moisture content' by Santer et. al., published in the journal PNAS in 2007, which corroborates Professor Sherwood's claim. However, I should point out that the claim was clearly attributed to Professor Sherwood and did not constitute factual content for the purposes of section 7.4.2(a) of the Editorial Policies.

Please be assured that your comments, including your suggestion for a follow-up article featuring the views of Dr Spencer and Professor Lindzen, have been noted and conveyed to relevant staff in ABC Innovation. Thank you for taking the time to write.

Yours sincerely
ABC Audience & Consumer Affairs


  1. Professor Sherwood's own research says "key uncertainties remain connected to atmospheric dynamics and the hydrological consequences
    of a moister atmosphere".
    See: "Sherwood, S. C., et al 2010), Tropospheric water vapor, convection,
    and climate, Rev. Geophys., 48, RG2001, doi:10.1029/2009RG000301"

    So it is just guesswork, like all climate science. And like all publicly funded climate researchers, he says: "More work is called for to understand how circulations on all scales are governed and what role water vapor plays. Suggestions are given for future research."

    This can be translated as "give us more tax-payers' money so we can continue with our hobby".

  2. Well spotted. More baseless bluster. Sherwood finds temperature increases with windgauges...

    He uses graphs where zero degrees of warming is colored red.


Please keep to the topic. Abusive comments and bad language are simply not tolerated. Note that your comment may take a little while to appear.

Note: Only a member of this blog may post a comment.