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 3, MARCH 1995
OF GENERAL INTEREST: CLIMATE CHANGE SCIENCE
"Biomass Burning: A Driver for Global Change," J.S.
Levine (NASA-Langley, Hampton VA 23681), W.B. Cofer III et al., Environ.
Sci. & Technol., 29(3), 120A-125A, Mar. 1995.
Biomass burning, primarily from African savannahs, contributes
as much as 40% of the gross carbon dioxide and 39% of the
tropospheric ozone. Observations from space and from
international field experiments have documented the extent and
frequency of fires and the concentrations of emitted carbon,
nitrogen, sulfur and halogen compounds. In addition to being an
instantaneous global source of atmospheric gases, burning
enhances the biogenic emission of nitric and nitrous oxides from
soils, and affects the reflectivity and emissivity of the Earth's
surface and its hydrological cycle. It is therefore a significant
driver of global change.
"Changes in Cloud Properties due to NOx Emissions," M.
Kulmala (Dept. Phys., POB 9 [Sitavuorenpenger 20 D], SF-00014,
Univ. Helsinki, Helsinki, Finland), P. Korhonen et al., Geophys.
Res. Lett., 22(3), 239-242, Feb. 1, 1995.
Discusses a mechanism as an alternative to the proposal that
the Northern Hemisphere may be warming more slowly than the
Southern Hemisphere because of the direct and indirect effects of
sulfate aerosols. The mechanism put forth involves increased
concentrations of condensable vapors such as HNO3 and HCl that
could activate an increased number of pre-existing aerosol
particles to act as cloud condensation nuclei. Since NOx
emissions are being reduced more slowly than SOx emissions, the
implications for climate change could be important.
the Role of CH4 in Atmospheric Chemistry: Sources,
Sinks and Possible Reductions in Anthropogenic Sources,"
P.J. Crutzen (M. Planck Inst. Chem., POB 3060, D-55020 Mainz,
Ger.), Ambio, 24(1), 52-55, Feb. 1995.
Discusses the sources and sinks of atmospheric methane, mostly
based on compilations by the IPCC but updated by the author's
ongoing studies. There are ample opportunities for substantially
reducing anthropogenic methane emissions; a 10% reduction would
achieve stabilization of atmospheric methane. Also shows that the
extensive use of catalytic converters to reduce NO emissions from
automobiles results in substantially larger emissions of N2O,
another important greenhouse gas.
"Iceberg Discharges into the North Atlantic on Millennial
Time Scales During the Last Glaciation," G.C. Bond
(Lamont-Doherty Earth Observ., Rte. 9W, Palisades NY 10964), R.
Lotti, Science, 267(5200), 1005-1010, Feb. 17,
Analysis of deep sea sediment cores shows that prominent
increases in iceberg calving recurred at intervals of 2000 to
3000 years, and correlate with warm-cold oscillations
(Dansgaard-Oeschger events) in Greenland ice cores. Each cycle
records synchronous discharges of ice from different sources, and
the cycles are decoupled from sea surface temperatures,
suggesting an atmospheric mechanism that caused rapid
oscillations in air temperatures above Greenland and in calving
from more than one ice sheet.
"Equable Climates During the Early Eocene: Significance of
Regional Paleogeography for North American Climate," L.C.
Sloan (Inst. Marine Sci., Univ. Calif., Santa Cruz CA 95064), Geology, 22(10),
881-884, Oct. 1994.
The character of continental-interior paleoclimate at
mid-latitudes, especially temperature, has been a major source of
debate over the past few years. In the climate model study
presented here, cases with six times the present level of CO2,
or with doubled CO2 and a large lake in western North
America, produced results most similar to proxy paleoclimate
interpretations. The presence of the lake is critical to
reproducing the early Eocene climate. (See RESEARCH NEWS.)
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