After reviewing more than 100 peer-reviewed studies, Thomas Huntington from the United States Geological Survey, has concluded that there is more water circulating as a consequence of global warming. This includes more rainfall and more evaporation, but there has not been more tropical storms or more floods over the last 100 years.
Huntington’s findings were published earlier this week in the Journal of Hydrology (Volume 319, No 1-4, pages 83-95) in a paper titled ‘Evidence for intensification of the global water cycle: Review and synthesis’.
Eureka Alert includes the following comment about the study:
“Although data are not complete, and sometimes contradictory, the weight of evidence from past studies shows on a global scale that precipitation, runoff, atmospheric water vapor, soil moisture, evapotranspiration, growing season length, and wintertime mountain glacier mass are all increasing. The key point with the glaciers is that there is more snowfall resulting in more wintertime mass accumulation – another indication of intensification.
“This intensification has been proposed and would logically seem to result in more flooding and more intense tropical storm seasons. But over the observational period, those effects are just not borne out by the data in a consistent way,” said Huntington.
Huntington notes that the long term and global scale of this study could accommodate significant variability, for example, the last two Atlantic hurricane seasons.
“We are talking about two possible overall responses to global climate warming: first an intensification of the water cycle being manifested by more moisture in the air, more precipitation, more runoff, more evapotranspiration, which we do see in this study; and second, the potential effects of the intensification that would include more flooding and more tropical storms which we don’t see in this study,” said Huntington.“
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Thanks to Benny Peiser for alerting me to this study.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Weeeeeellll. The global warming theory suggests more intense storms but not more frequent. As has been recently reported:
Journal reference: Nature (DOI:10.1038/nature03906
Increasing destructiveness of tropical cyclones over the past 30 years
Kerry Emanuel says:
Theory and modelling predict that hurricane intensity should increase with increasing global mean temperatures, but work on the detection of trends in hurricane activity has focused mostly on their frequency and shows no trend. Here I define an index of the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone, and show that this index has increased markedly since the mid-1970s. This trend is due to both longer storm lifetimes and greater storm intensities. I find that the record of net hurricane power dissipation is highly correlated with tropical sea surface temperature, reflecting well-documented climate signals, including multi-decadal oscillations in the North Atlantic and North Pacific, and global warming. My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and—taking into account an increasing coastal population—a substantial increase in hurricane-related losses in the twenty-first century.
Emanuel’s paper also says that the power index is up in all ocean basins around the world.
Of course the global meeting on hurricanes in South Africa reminds us that the field is controversial with experts divided – what else is new on this front?
Anecdotally I have previously also remarked how strong tropocal cyclones have been in our region in recent years – the last being Ingrid (Top End to Kimberley). Vance (WA), Nancy and Zoe (Pacific) have also all been very intense high velocity systems.
CSIRO has undertaken quite a bit of work of late on extreme events and return frequencies with high interest from the Gold Coast City Council.
http://www.csiro.au/files/mediaRelease/mr2003/Prextreme.htm
“Floods already cause more damage in Australia than any other natural disaster in terms of cost to the community,” says Dr Abbs. “In southern Queensland and northern NSW, our results suggest damage costs associated with flooding would increase by half if sea level rose by 20cm, and more than double if sea level were to rise by 40cm.”
A very interesting sideline on the water cycle in the journal, Nature, suggests that in all continents that the increase in atmospheric CO2 over the last century is causing plants to transpire less water less with signficant increases in runoff. Gedney et al. investigated four plausible contributors to observed increases in runoff: climate change leading to changes in temperature and precipitation; land-use change and consequent changes in vegetation cover; so called ‘solar dimming’, resulting from an increasingly hazy atmosphere; and the direct
effect of CO2 on plant transpiration. The
effects of each of these on surface runoff were
simulated using a sophisticated land-surface
and vegetation model, and the results of the
model were compared with historical observations
of continental runoff. The authors’ analysis
shows that model-simulated runoff trends
are consistent with the observed trend only
when the direct effect of CO2 on transpiration
is included in the simulation. So they attribute
increases in continental runoff over the past
century to the physiological effect of elevated
atmospheric CO2.
The model successfully captures the climate driven inter-annual runoff variability, but twentieth-century climate alone is insufficient to explain the runoff trends. Instead we find that the trends are consistent with a suppression of plant transpiration due to CO2-induced stomatal closure. The work was done over North and South America, Africa, Asia and Europe but not Australia.
Vol 439|16 February 2006|doi:10.1038/nature04504
Detection of a direct carbon dioxide effect
continental river runoff records
N. Gedney1, P. M. Cox2, R. A. Betts3, O. Boucher3, C. Huntingford4 & P. A. Stott5
1Met Office, Hadley Centre for Climate Prediction and Research (JCHMR), Maclean Building, Wallingford OX10 8BB, UK. 2Centre for Ecology and Hydrology Dorset, Winfrith
Technology Centre, Winfrith Newburgh, Dorchester DT2 8ZD, UK. 3Met Office, Hadley Centre for Climate Prediction and Research, Fitzroy Road, Exeter EX1 3PB, UK. 4Centre
for Ecology and Hydrology Wallingford, Maclean Building, Wallingford OX10 8BB, UK. 5Met Office, Hadley Centre for Climate Prediction and Research (Reading Unit),
Meteorology Building, University of Reading, Earley Gate, Reading RG6 6BB, UK.
And http://www.eurekalert.org/pubnews.php also lead me to
Radar altimetry confirms global warming is affecting polar glaciers
http://www.esa.int/esaEO/SEMTQUNVGJE_planet_0.html
17 March 2006
Scientists have confirmed that climate warming is changing how much water remains locked in the Antarctic and Greenland ice sheets, according to an article published in the Journal of Glaciology.
Using radar altimeter data from ESA’s ERS-1 and ERS-2, Jay Zwally, a scientist at NASA’s Goddard Space Flight Center, and his colleagues mapped the height of the ice sheets and found there was a net loss of ice from the combined sheets between 1992 and 2002 and a corresponding rise in sea level.
And Benny Peiser is famous too – he’s been reviewed at the new site that is eclipsing realclimate -http://illconsidered.blogspot.com/2006/03/what-about-peiser.html
http://illconsidered.blogspot.com/ is run by Coby Beck, Contrarian Slayer, of UseNet fame. i.e. sci.environment and alt.global-warming
Some of your non believers Phil; the ones looking for excuses NOT to do anything yet may get a bit of a wind up overnight.
My own analysis of daily rainfall records for the past century at Mullumbimby indicate that while the last 25 years has had lower total rainfall, the actual growing seasons have improved on both the sixties and seventies, and the comparatively drier earlier quarter centuries.
Put simply, a cyclone may be good for filling totally redundant Dams for urban water supply but they aren’t much good for keeping young possums alive in November.
It is also possible that the increase in the world’s area of irrigated land is responsible for the increase in total water in circulation. Water is captured in dams and prevented from flowing into the sea. It is then either evaporated from the dam or transpired by a crop. And in both cases it amounts to a newly created source of evapostanspiration.
So we now have dams that improve water cycling, reduce sedimentation, protect cities from flooding, prevent destruction of coral by either fresh water or silt and maintain biodiversity.