February 28, 2007
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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 10, NUMBER 6, JUNE 1997
IMPACTS ON HYDROLOGY
"Summer Drought in Northern Midlatitudes in a Time-Dependent CO2
Climate Experiment," J.M. Gregory (Hadley Ctr., Meteor. Off., London Rd.,
Bracknell, Berkshire RG12 2SY, UK.; e-mail: firstname.lastname@example.org), J.F.B.
Mitchell, A.J. Brady, J. Clim., 10(4), 662-686, Apr. 1997.
This experiment with a coupled ocean-atmosphere GCM looked at changes in the
occurrence of drought in summer in southern Europe and central North America,
regions where current conditions are fairly dry. Although the results should not
be taken as firm predictions, they point to the possibility of large increases
in the severity of drought as a consequence of climate change.
"Water Allocation in a Changing Climate: Institutions and
Adaptation." (See PROF. PUBS./GEN. INTEREST & COMMENTARY, this
Global Climate Change Digest issue--June 1997.)
"Water Resources: Agriculture, the Environment, and Society-An
Assessment of the Status of Water Resources," D. Pimentel (College of
Agriculture & Life Sci., Cornell Univ., Ithaca NY 14853), J. Houser et al.,
BioScience, 47(2), 97-106, Feb. 1997. (See PROF. PUBS./GLOBAL
ENVIRONMENT, Global Climate Change Digest, Mar. 1997.)
"Century-Long Variations in United States Drought Severity,"
R.C. Balling Jr. (Dept. Geog., Arizona State Univ., Tempe AZ 85287), Agric. &
Forest Meteor., 82(1), 293-299, Dec. 1996.
For the central U.S., models are suggesting that drought frequency,
magnitude and duration will increase. This paper updates analyses of drought
severity trends, finding little support for any increase across the U.S. during
the past 100 years, a time when there has been substantial buildup of greenhouse
"Greater Drought Intensity and Frequency before AD 1200 in the
Northern Great Plains, USA," K.R. Laird (Paleoecological Environ. Assess. &
Res. Lab.-PEARL, Dept. Biol., Queen's Univ., Kingston ON K7L 3N6, Can.; e-mail:
email@example.com), S.C. Fritz et al., Nature, 384(6609),
552-554, Dec. 12, 1996.
Presents a climate reconstruction over the past 2,300 years based on lake
salinity fluctuations inferred from fossil diatom assemblages. Droughts of
greater intensity than the one that caused the 1930s Dust Bowl were more
frequent before AD 1200; at that time the atmospheric circulation anomalies that
produce drought today were more frequent and persistent. A return to this
earlier mode of climate variability in this region (a possibility raised by
model simulations of increased CO2) would be devastating.
"Droughts over Southern Africa in a Doubled-CO2 Climate," A.M.
Joubert (Clim. Res. Group, Univ. Witwatersrand, PO Wits, Johannesburg, S.
Africa; e-mail: firstname.lastname@example.org), S.J. Mason, J.S. Galpin, Intl. J.
Climatol., 16(10), 1149-1156, Oct. 1996.
Output from the CSIRO nine-level GCM showed that changes in annual mean
rainfall are not expected to be significant. However, an increase was found in
the probability of dry years in the tropics, the southwest of the subcontinent,
and over western and eastern parts of South Africa and southern Mozambique,
where large percentage increases in the most intense dry spells are indicated.
The model also indicates a shift in the frequency distribution of daily rainfall
events. Such a small change may influence the frequency of mid-summer droughts
during the peak summer rainfall period of December to February.
Comment and reply on a paper by J.G. Lockwood ("Will Rising Levels
of Atmospheric CO2 and Temperature Lead to Enhanced or Suppressed Rates of
Evapotranspiration?"), Weather, 51(8), 285-288, Aug. 1996.
"Future Availability of Water in Egypt: The Interaction of Global,
Regional and Basin Scale Driving Forces in the Nile Basin," D. Conway
(Clim. Res. Unit, Univ. E. Anglia, Norwich NR4 7TJ, UK), M. Krol et al., Ambio,
25(5), 336-342, Aug. 1996.
The global (climate change) and regional (land-use change) driving forces
are taken from the IMAGE 2.0 model and from climate model simulations. Regional
hydrologic models are used to calculate impacts at the river-basin level as
influenced by water resource management. The combined effects of these driving
forces range from a large water surplus to a large water deficit by the year
2050. This wide range of results arises from uncertainties in the integrated
modeling approach, and from the ways Egypt may approach population growth,
agricultural policy and human aspirations for future water use.
"El Ni?o-Like Climate Change in a Model with Increased
Atmospheric CO2 Concentrations," G.A. Meehl (NCAR, POB 3000, Boulder CO
80307), W.M. Washington, Nature, 382(6586)56-60, July 4, 1996.
(See PROF. PUBS./GEN. INTEREST & COMMENTARY, Global Climate Change
Digest, Aug. 1996.)
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