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 8, NUMBER 9, SEPTEMBER 1995
GLOBAL & REGIONAL MODELING
"Evaluation of Total Cloudiness and Its Variability in the
Atmospheric Model Intercomparison Project," B.C. Weare (Atmos. Sci. Dept.,
Hoagland Hall, Univ. California, Davis CA 95616), I.I. Mokhov et al., J.
Clim., 8(9), 2224-2238, Sep. 1995.
Compares the total cloudiness from 29 models with observational estimates
from the ISCCP C2, Nimbus-7 and Meteor. After global means are removed, the
root-mean-square differences between the annual means of the model calculations
and the C2 observations vary from 2-4 times the differences between the C2 and
Meteor observations. Deficiencies with respect to the model simulations of the
mean seasonal cycle are also pronounced. However, the models that have more
sophisticated physical processes tend to better simulate the cloud observations.
"Atmospheric Response to Tropical Denuding of Vegetation," R.C.
Raghava (Ctr. Atmos. Sci., Indian Inst. Technol., New Delhi 110 016 India), K.
Laval et al., Atmos. Environ., 29(16), 1963-2000, Aug. 1995.
Simulated atmospheric circulations during June, July and August 1988 with
LMD Atmospheric GCM using a classified vegetation global cover, with and without
the tropical vegetation. Results show how tropical forest has a pronounced
positive impact on precipitation, and how it modulates the Indian monsoon.
"Long-Term Changes in the Acid and Salt Concentrations of the
Greenland Ice Core Project Ice Core from Electrical Stratigraphy," E.W.
Wolff (Brit. Antarctic Survey, High Cross, Madingley Rd., Cambridge CB3 0ET,
UK), J.C. Moore et al., J. Geophys. Res., 100(D8),
16,249-16,263, Aug. 20, 1995.
Records of electrical conductivity measurement (ECM) and dielectric profile
(DEP) are dominated by the acidity of the ice (strongly acidic in warm periods
and strongly alkaline in cold periods). These results bear on the deduced
concentration of cloud condensation nuclei over the Northern Hemisphere, and may
have implications for climate modeling.
"The Chemical Composition of Ancient Atmospheres: A Model Study
Constrained by Ice Core Data," P. Martinerie (Lab. Glaciol. & Geophys.
l'Environ., BP 96, F-38402 St.-Martin-d'Heres Cedex, France), G.P. Brasseur, C.
Granier, ibid., 100(D7), 14,291-14,304, July 20, 1995.
Adapted a coupled chemistry radiation transport 2-D model of the lower and
middle atmosphere, to study the chemical composition of the atmosphere before
industrialization and at the last glacial maximum. The model was constrained by
trace gas concentrations (CO2, CH4 and N2O) derived from polar ice records.
Infers changes in middle atmosphere temperature, ozone layer and oxidation
capacity of the atmosphere (e.g., CH4 lifetime) over the last 18,000 years.
Two items from J. Clim, 8(6), June 1995:
"Simulation of El NiñoSouthern Oscillation-Like
Variability in a Global AOGCM and Its Response to CO2 Increase," S. Tett
(H107 Hadley Ctr., U.K. Meteor. Off., London Rd., Bracknell, Berkshire RG12 2SY,
UK), 1473-1502. Examined a 75-year integration of a coupled atmosphere-ocean
model for tropical interannual variability. Found no significant change in the
one-to-ten-year interannual variance of SST in the east Pacific, suggesting that
the size of the SST anomalies during warm or cold events in a greenhouse world
may not be significantly different from those of today.
"Seasonal Surrogate for Climate," R.S. Lindzen (Dept. Meteor.,
Mass. Inst. Technol., Cambridge MA 02139), B. Kirtman et al., 1681-1684.
Illustrates a simple necessary condition for a short-term event serving as a
surrogate for climate, in the evaluation of model performance.
"Modeling Climate Change in the Absence of Climate Change Data,"
J.W. Skiles (Johnson Controls, MS 239-20, NASA Ames, Moffett Field CA 94035),
Clim. Change, 30(1), 1-6, May 1995.
An editorial comment that climate change prediction exercises are done with
invalid GCMs and in the absence of validation data. Until concrete climate
change data becomes available, particularly for runoff and river flow,
validation of GCM output will remain a qualitative exercise. Those using GCM
output need to state the confidence they place in those predictions and the
reasons for their confidence.
Three items from Global & Planetary Change, 10(1-4),
"Global Climate Sensitivity to Tropical Deforestation," K.
McGuffie (Dept. Appl. Phys., Univ. Technology, Sydney, POB 123, Broadway NSW,
2007 Australia), A. Henderson-Sellers et al., 97-128. Used a modified version of
the NCAR CCM. A 14-year control integration is followed by a 6-year
deforestation experiment in which tropical moist forest is replaced by scrub
grassland in the Amazon Basin, S.E. Asia and tropical Africa. The impacts on
regional climate varied for each deforested region, with the largest
disturbances taking place in the Amazon Basin, and the least changes seen for
"A Comparison of the CCM1-Simulated Climates for Pre-Industrial and
Present-Day CO2 Levels," S. Marshall (Dept. Geog. & Earth Sci., Univ.
N. Carolina, Charlotte NC 28223), M.E. Mann, 163-180. Used an atmospheric CO2
level of 265 ppm (pre-industrial) and 330 ppm (ca. 1975), and included
statistical estimates of the level of confidence in the implied changes. Found a
relatively large model response in surface temperature and a smaller response in
precipitation, surface pressure and storm track fields. A t-statistic of
model results indicates a significant surface temperature response to a
relatively small change in CO2, above the inherent model variability.
Observations of global surface temperature anomalies for 1890-1990 show some
similarities to the model, especially a warming in regions of the wintertime
Northern Hemisphere of 1-3° C.
"Low-Frequency Variability and CO2 Transient Climate Change. Part 2:
EOF Analysis of CO2 and Model-Configuration Sensitivity," G.C. Campbell
(NCAR, POB 3000, Boulder CO 80307), T.G.F. Kittel et al., 201-216. Examined the
monthly variance structure of several GCM simulations. Four simulations were
evaluated in which present-day and doubled CO2 experiments with the same
atmospheric GCM were coupled to: (1) a simple nondynamic mixed-layer ocean
(mixed-layer model); and (2) an ocean GCM (coupled model). Found that different
model configuration has a stronger effect on simulated interannual variability
globally than does altered CO2 forcing.
"Impact of the Ongoing Amazonian Deforestation on Local
Precipitation: A GCM Simulation Study," G.K. Walker, Y.C. Sud (Clim. &
Radiation Branch, Code 913, NASA-Goddard, Greenbelt MD 20771), R. Atlas, Bull.
Amer. Meteor. Soc., 76(3), 346-361, Mar. 1995.
Investigates deforestation effects through ensembles of five-day
integrations with the Goddard Laboratory for Atmospheres GCM equipped with a
simple biosphere model. Effects include decreased precipitation extending in a
complex fashion downwind, and a significant increase in drag force due to
reduced surface roughness.
"Ocean Modelling Efforts in the Global Climate System," J.-O.
Wolff (Antarctic Cooperative Res. Ctr., Univ. Tasmania, GPO Box 252C, Hobart,
Tasmania 7001, Australia), Aust. Meteor. Mag., 43(4), 263-281,
Gives an extensive overview of ocean models that have been used to elucidate
the role of the oceans in different frequency ranges of the climate variability
spectrum. Discusses coupling to atmospheric climate models and the use of models
to study the role of the oceans in climate dynamics. (Invited paper, 1994
National Australian Meteorological and Oceanographic Society Conference.)
"A Self Organization Climate Model," Yi Chuixiang (Dept.
Environ. Sci., Beijing Normal Univ., Beijing 100875), Wu Rongsheng, Chinese
J. Atmos. Sci., 18(3), 251-262, 1994.
Uses a highly simplified nonlinear model, which shows a self-organization
mechanism for cloud-radiation interaction, to study important feedback processes
in the climate system.
"Cloudiness Parameterization and Verification in a Large-Scale
Atmospheric Model," A.P. Dastoor (Recherche en Prévision Numérique,
Serv. Environ. Atmos., 2121 Rte. Trans-Canadienne, Dorval, PQ H9P 1J3, Can.),
Tellus, 46A(5), 615-634, Oct. 1994.
A convective and stratiform condensation scheme, in which cloud amount
estimation is a predictive variable, is implemented in the Canadian global
spectral model. The total cloud cover is better estimated as the sum of separate
estimates of convective and stratiform cloudiness, within the framework of the
condensation processes parameterized.
"Simulation of the Possible Influence of Methane and Carbon Monoxide
Release on the Global Atmospheric Composition and the Greenhouse Effect,"
I.L. Karol (Voyeykov Main Geophys. Observ.), A.A. Kiselev, V.A. Frolkis, Phys.
Atmos. & Ocean, 29(5), 597-601, Apr. 1994. English translation
from the Russian Edition, Sep.-Oct. 1993.
Used a one-dimensional radiative-photochemical model to consider expected
21st century changes based on IPCC scenarios, taking into account changes of air
temperature and humidity due to the effects of greenhouse and other trace gases.
Atmospheric changes found to occur under greenhouse processes affect the gas
composition and increase CO content in the lower stratosphere due to
decomposition of CH4 by atomic Cl.
"Global Coupled General Circulation Models," G.A. Meehl (NCAR,
POB 3000, Boulder CO 80307), Bull. Amer. Meteor. Soc., 76(6),
951-957, June 1995.
Presents major conclusions and recommendations on the status of coupled GCMs
from a workshop convened by the World Climate Research Program (Oct. 1994, La
Jolla, Calif.). Participants concluded that improved communication among those
engaged in this activity will be important to further progress.
"Using Paleoclimates to Predict Future Climate: How Far Can Analogy
Go?" C. Covey (Global Clim. Res. Div., Lawrence-Livermore Natl. Lab., POB
808, Livermore CA 94550), Clim. Change, 29(4), 403-407, Apr.
An extensive comment on the disagreement between GCMs and paleodata, which
should be cause for concern among those who subscribe to the conventional
wisdom. The disciplines of geology and meteorology must be brought together if
we are to fully confront theory with observation.
"Global-Mean Temperature and Sea Level Consequences of Greenhouse Gas
Concentration and Stabilization," T.M.L. Wigley (Clim. Res. Unit., Univ. E.
Anglia, Norwich NR4 7TJ, UK), Geophys. Res. Lett., 22(1), 45-48,
Jan. 1, 1995.
Uses models previously employed by the Intergovernmental Panel on Climate
Change to calculate scenarios of future CO2 levels stabilized at 350-750 ppmv,
to the year 2500. Uncertainties are large, but results show that even with
concerted efforts at stabilization, substantial increases in temperature and sea
level can be expected over the next century. Sea level could continue to
increase for many centuries after stabilization due to the extremely long time
scales associated with the deep ocean (thermal expansion) and with large ice
"The Current State and Future Direction of Eulerian Models in
Simulating the Tropospheric Chemistry and Transport of Trace Species: A Review,"
L.K. Peters (Dept. Chem. Eng., Virginia Polytechnic Inst., Blacksburg VA 24061),
C.M. Berkowitz et al., Atmos. Environ., 29(2), 189-222, Jan.
Central improvements that would result in a "third generation"
model involve feedback processes between meteorology and chemistry, aerosol
formation in cloud development, and impacts of chemical perturbations on
radiation, climate and biogeochemical cycles. Also includes a comparison of
characteristics of existing models, and extensive references.
"A Comparison of GCM Sensitivity to Changes in CO2 and Solar
Luminosity," S. Marshall (Dept. Geog., Univ. N. Carolina, Charlotte NC
28223), R.J. Oglesby et al., Geophys. Res. Lett., 21(23),
2487-2490, Nov. 15, 1994.
Experiments with the NCAR climate model are compared using a formal
sensitivity analysis. Since the nature of the model response does not seem to be
sensitive to the nature of the forcing, validation of model performance using
warm climates of the recent past may be a good indication of its ability to
model future warming from CO2.
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Index of Abbreviations