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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 2, NUMBER 10, OCTOBER 1989

PROFESSIONAL PUBLICATIONS...
TREND ANALYSIS

Item #d89oct71

"North American Total Cloud Amount Variations this Century," A. Henderson-Sellers (Sch. Earth Sci., Macquarie Univ., North Ryde, N.S.W. 2109, Australia), Global Plan. Change, 1(3), 175-194, Aug. 1989.

Reviews records of mean monthly total cloud amount from 143 locations in North America recorded for more than eighty years. The records, which are spatially consistent and temporally coherent, show a general tendency for total cloud amount to increase over the period, with the greatest increase between 1930 and 1950. Discusses possible reasons for such an increase. The most likely cause is clouds generated in the form of jet aircraft condensation trails, but the largest increase identified pre-dates the widespread introduction of such aircraft.

Item #d89oct72

"Testing the Global Warming Hypothesis," A.A. Tsonis (Univ. Wisconsin, POB 413, Milwaukee WI 53201), Geophys. Res. Lett., 16(8), 795-797, Aug. 1989.

The temperature record for the global surface air temperature indicates that six of the warmest years occurred in the period 1980-1988. The authors conducted a statistical analysis to determine the likelihood that this outcome arises purely by chance through the natural variability of the system. Results indicate that the probability of such an outcome is between 0.010 and 0.032.

Item #d89oct73

"Tropical Pacific Climate Trends Since 1960," E.S. Posmentier, M.A. Cane (Lamont-Doherty Geolog. Observ., Columbia Univ., Palisades NY 10964), S.E. Zebiak, J. Clim., 2(7), 731-736, July 1989.

Investigates trends in tropical Pacific sea surface temperature and in sea level, which has repeatedly been shown to be closely related to the winds. Results suggest that sea levels since 1960 have been rising oceanwide at about 3.5 cm per decade, while simultaneously tilting about 2 cm per decade higher in the east and lower in the west, and that surface temperatures have been rising about 0.6° C per decade. These results are not consistent with the apparent wind change. Supports the contention that the apparent wind changes are an artifact introduced by changes in measurement technique.

Item #d89oct74

"Northern Hemisphere Temperature Trends: A Possible Greenhouse Gas Effect?" D.J. Karoly (Atmos. & Ocean Sci. Prog., Princeton Univ., POB 308, Princeton NJ 08542), Geophys. Res. Lett., 16(5), 465-468, May 1989.

Uses radiosonde temperature data from 147 stations in the Northern Hemisphere for the period 1964-1985 to investigate recent temperature trends in the troposphere and lower stratosphere. An index designed to identify a greenhouse signal was computed from the station data. This index has a positive trend at most stations, consistent with the greenhouse effect. Over the hemisphere the signal is statistically significant. Discusses possible mechanisms to explain the trends.

Item #d89oct75

"Spatial Patterns in Recent Worldwide Temperature Trends," P.D. Jones, T.M.L. Wigley, C.K. Folland (Meteor. Off., London Rd., Bracknell, Berkshire RG12 2SZ, UK), D.E. Parker, Clim. Monitor, 16(5), 175-185, Annual 1987 (published in 1988).

Suggests that, if present day climate trends are due to the influence of greenhouse gases alone, at least half of the greenhouse-gas-induced warming should have occurred in the last forty years. Warming over this period has occurred mainly since 1975. The warming is far from uniform and some areas of the Northern Hemisphere still show a net cooling of 1° C or more since 1947. Concludes that global temperature changes cannot be explained by greenhouse gas theory alone.

Item #d89oct76

"The Influence of ENSO on Global Temperatures," P.D. Jones (Clim. Res. Unit, Univ. E. Anglia, Norwich NR4 7TJ, UK), ibid., 17(3), 80-89, June-Aug. 1988.

Uses the Southern Oscillation Index (SOI) to analyze the influence on global temperatures of the El Niño/Southern Oscillation, which has been suggested as an alternate explanation instead of greenhouse warming for recent exceptionally warm years. A correlation analysis is used to statistically remove the SOI effect from the temperature record. The resulting hemispheric and global air temperatures still show an increase over the period 1880 to the present.