February 28, 2007
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FROM VOLUME 9, NUMBER 9, SEPTEMBER 1996
TREND ANALYSIS: ATMOSPHERIC PROPERTIES
Increases in Low-Frequency Variability of Precipitation over the Past Century,"
A.A. Tsonis (Dept. Geosci., Univ. Wisconsin, Milwaukee WI 53201), Nature,
382(6593), 700-702, Aug. 22, 1996.
Examines the nature of time fluctuations in several global data sets of
precipitation. Finds that the global mean precipitation has not changed, in
agreement with other analyses, but fluctuations about the mean have increased
significantly on decadal to multi-decadal time scales. Over the past centuryduring
which climate warming has occurredfluctuations on those time scales have
made extremes more probable. This result is consistent with predictions from
model simulations of global climate-warming scenarios.
in the Frequency of Intense Atlantic Hurricanes During the Past Five Decades,"
C.W. Landsea (Clim. & Global Change, NOAA AOML/Hurricane Res. Div., 4301
Rickenbacker Causeway, Miami FL 33149; e-mail: email@example.com), N.
Nicholls et al., Geophys. Res. Lett.,
23(13), 1697-1700, June 15, 1996.
Contrary to the expectation of many that tropical cyclones may be developing
more frequently due to greenhouse gases, the Atlantic basin has in recent
decades seen a significant trend of fewer intense hurricanes and weaker cyclones
overall. In addition, the maximum intensity reached in each year has shown no
appreciable change. However, 1995 has at least temporarily heralded the return
of Atlantic basin hurricanes. Several years must pass before we will know if
this marks the beginning of a new regime of active hurricanes.
Conference on Global Change and the Polar Climate, 7-10 November 1995, Tsukuba,
Japan," J.E. Walsh (Dept. Atmos. Sci., Univ. Illinois, 102 Atmos. Sci.
Bldg., 105 S. Gregory Ave., Urbana IL 61801), H.L. Tanaka, G. Weller, Bull.
Amer. Meteor. Soc., 77(6), 1268-1273, June 1996.
A recurring theme of the conference was the possibility of an abrupt and
surprising climate change involving the high latitudes. Recent results of
climate models suggest that the enhanced greenhouse effect should be detectable
in the polar regions and elsewhere in the next decade or two. This conference
highlighted possible early indications of anthropogenic changes and called
attention to the need to monitor the polar climate system carefully for rapid,
complex, and perhaps surprising changes in the near future.
"Recent Trends in
Rain Gauge Precipitation Measurements from the Tropical Pacific: Evidence for an
Enhanced Hydrologic Cycle," M.L. Morrissey (Oklahoma Clim. Survey, 1210
Sarkeys Energy Ctr., Norman OK 73019; e-mail: firstname.lastname@example.org), N.E. Graham,
Analysis of recently compiled rain gauge measurements shows a trend towards
increasing precipitation in the central tropical Pacific during the period
1971-1990. The data corroborate previous results based on satellite
measurements, shipboard observations, and numerical models. The result is also
consistent with suggestions that an enhancement of the tropical hydrologic cycle
has been responsible for the increase in globally averaged tropospheric
temperature during the past two decades.
in Arctic Summer Ice Cover and Linkages to Atmospheric Circulation Anomalies,"
J.A. Maslanik (Ctr. for Astrodynamics Res., CB431, Univ. Colorado, Boulder CO
80309; e-mail: jimm@northwind. colorado.edu), M.C. Serreze, R.G. Barry Geophys.
Res. Lett., 23(13), 1677-1680, June 15, 1996.
The net trend in Arctic Ocean sea ice, assumed to be a sensitive indicator
of climatic conditions, was -0.6% per year from November 1978 through December
1995. Linkages are proposed between this trend and a sharp increase since 1989
in the frequency of low pressure systems over the central Arctic. The
sensitivity of ice cover to regional atmosphere-ice interactions points to the
need for sophisticated treatment of sea ice in climate models.
Two items in J.
Clim., 9(6), June 1996:
"Evaluation of Long-Term Changes in Radiation, Cloudiness and Surface
Temperature on the Territory of the Former Soviet Union," G.M. Abakumova, .
.V. Russak (Inst. Astrophys., Estonian Acad. Sci., EE2444 Toravere, Estonia;
e-mail: email@example.com) et al., 1319-1327. A statistically significantly decrease
has been found in 60% of the time series of global radiation annual totals
obtained from 160 actinometric stations. Increased cloudiness and atmospheric
turbidity are evaluated as the main causes of the trend. Comparison of stations
in rural and urban settings illustrates the influence of urban air pollution on
radiation transfer in the atmosphere, as well as on cloudiness and air
"Intrannual Variability in Reconstructed Canadian Snow Cover,
1915-1992," R.D. Brown (Atmos. Environ. Serv., 2121 Trans Canada Hwy.,
Dorval PQ H9P 1J3, Can.), B.E. Goodison, 1299-1318. Seasonal snow cover
information for southern Canada was reconstructed from daily snowfall and
maximum temperature data using a simple mass balance approach. There was no
evidence of statistically significantly long-term trends in snow cover in any of
the regions, but the data suggested that winter (Dec.-Feb.) snow cover had
increased and spring snow cover had decreased over much of the area. The
influence of teleconnection patterns was investigated.
Photographs Show No Climate-Induced Changes in Woody Vegetation in the Sudan,
1943-1994," W.E. Schlesinger (Dept. Botany, Duke Univ., Durham NC 27708;
e-mail: firstname.lastname@example.org), N. Gramenopoulos, Global Change Biology,
2(2), 137-141, Apr. 1996.
Woody plants are often better indicators than grasses of long-term climate
shifts in arid regions because they are buffered against short-term fluctuations
by their deep root systems. This study examines data held in classified
intelligence archives to determine trends in the distribution of woody plants in
western Sudan. Despite several decades of recent drought, there is no
significant evidence of a trend.
"Trends in the
Intensity and Frequency of Heavy Rainfall in Tropical Australia and Links with
the Southern Oscillation," R. Suppiah (Div. Atmos. Res., CSIRO, PMB 1,
Aspendale, Vic. 3195, Australia), K.J. Hennessy, Aust. Meteor. Mag.,
45(1), 1-17, Mar. 1996.
Daily rainfall data between September and April from 53 stations were
examined for the period 1910 to 1989. Increasing trends in the 90th and 95th
percentile rainfall intensity and frequency occur at most stations, but few are
statistically significant. Relationships between the Southern Oscillation Index
and these heavy rainfall parameters were stronger during 1950-1989 relative to
1910-1949, suggesting a change in large-scale atmospheric circulation patterns.
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