8 Comments

1. Chris de Freitas: usual suspect.

   Best,

   D

2. New Zealand seems to have more than its fair share of climate-change sceptics. It must be the equable climate.

3. John

   For a more balanced overall assessment I suggest to consult this paper: Thomas G. Huntington, Evidence for intensification of the global water cycle: Review and synthesis. Journal of Hydrology. Volume 319, Issues 1-4 , 15 March 2006, Pages 83-95 http://tinyurl.com/p9qtp

   One of the more important questions in hydrology is: if the climate warms in the future, will there be an intensification of the water cycle and, if so, the nature of that intensification? There is considerable interest in this question because an intensification of the water cycle may lead to changes in water-resource availability, an increase in the frequency and intensity of tropical storms, floods, and droughts, and an amplification of warming through the water vapor feedback. Empirical evidence for ongoing intensification of the water cycle would provide additional support for the theoretical framework that links intensification with warming. This paper briefly reviews the current state of science regarding historical trends in hydrologic variables, including precipitation, runoff, tropospheric water vapor, soil moisture, glacier mass balance, evaporation, evapotranspiration, and growing season length. Data are often incomplete in spatial and temporal domains and regional analyses are variable and sometimes contradictory; however, the weight of evidence indicates an ongoing intensification of the water cycle. In contrast to these trends, the empirical evidence to date does not consistently support an increase in the frequency or intensity of tropical storms and floods.

4. Benny –

   Thanks. That is a most useful paper. It seems entirely consistent with Dai’s findings, especially on drought, which is the issue of most interest to me. It also seems to put the lie to de Freitas’ contention that the notion of increasing droughts is “not based on science.”

   As an aside, your treatment of the Huntington study in the March 17 CCNet seems an interesting example of selective emphasis in your presentation of climate change research. In your headline, you chose to emphasize one of a number of Huntington’s findings: the lack of evidence for increased frequency of tropical storms. That is certainly accurate, as is another of his findings that you chose not to highlight – consistent evidence in the majority of studies evaluated for increasing drought.

5. John

   If you look carefully at the 17 March CCNet issue, you will note that my headline based on Huntington’s own press release. The emphasis was essentailly his own:
   http://www.eurekalert.org/pub_releases/2006-03/usgs-cod031506.php

   Also, I think you misrepresent Chris de Freitas’ point. He does not rule out the possibility of local droughts or floods as a result of moderate warming, but criticised “the fear-mongering about more droughts and more floods” which is indeed unjustified given that many societies around the world (except the poorest of the poor) have learned quite well to cope with the occasional drought or flood.

6. John

   Here is just one more thought and some reading suggestions to back up my key argument about droughts:

   Perhaps the risk of local droughts has really increased slightly since the 1970s. However, much more important is this salient trend: the number of people killed globally as a result of drought and starvation has fallen dramatically during the same period of time. http://en.wikipedia.org/wiki/Drought. Evidently, in nearly all countries (except a few of the poorest African states), the iniquitous correlation between droughts and starvation does no longer exists.

   People who want to learn more about the social and economic rather than geophysical aspects of drought and starvation may wish to consult the book by Nobel Laureate Amartya Sen’s “Poverty and Famines: An Essay on Entitlement and Deprivation.” http://www.amazon.com/gp/product/0198284632/103-4039393-8119026?v=glance&n=283155 – (see also http://finance.sauder.ubc.ca/~bhatta/BookReview/arrow_on_sen's_poverty_and_famine.html ).

   Another extremely illuminating discussion on modern droughts and their diminishing impact on food production can be found in Julian Simon’s “The Ultimate Resource” http://www.juliansimon.com/writings/Ultimate_Resource/TCHAR07.txt

   In short, given the agrotechnological advances together with the increasing cooperation of the international community during the last 50 years (including the Green Revolution and the recent invention of drought-resistant GM crops), there is absolutely no rationale for alarm or fear-mongering.

7. Ah, yes, Cornucopian philosophy based on ignorance of geometry. Excellent.

   And Benny acts as if

   Empirical evidence for ongoing intensification of the water cycle would provide additional support for the theoretical framework that links intensification with warming.

   doesn’t yet exist.

   Huh. Sounds like fear-mongering that there’s no evidence. Or maybe there’s fear that there is and there is fear the evidence will wash out the FUD.

   Huh, Ben?

   Best,

   D

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