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 9, NUMBER 5, MAY 1996
(See also Prof. Pubs./Anthropogenic Emissions/Methane, this issue of the Global Climate Change Digest--May 1996.
"Atmospheric Methane at Mauna Loa and Barrow Observatories:
Presentation and Analysis of in situ Measurements," E.J.
Dlugokencky (CMDL, NOAA, 325 Broadway, Boulder CO 80303), L.P. Steele et al.,
J. Geophys. Res., 100(D11), 23,103-23,113, Nov. 20, 1995.
Describes several semi-continuous, in situ measurements made between
1986 and 1994, and examines features of the records ranging from the diurnal
cycle to seasonal cycles and trends. The semi-continuous nature of the records
are necessary for understanding implications concerning methane sources and
sinks. The average trend at Mauna Loa was 9.7 ppb per year, decreasing at a rate
of 1.5 ppb per year; the trend at Barrow was 8.5 ppb per year, decreasing at 2.1
ppb per year.
"Intrapermafrost Gas Hydrates from a Deep Core Hole in the Mackenzie
Delta, Northwest Territories, Canada," S.R. Dallimore (Geol. Survey of
Canada, 601 Booth St., Ottawa K1A 0E8, Can.), T.S. Collett, Geology,
23(6), 527-530, June 1995.
Reports the first confirmed occurrence of gas hydrates within ice-bonded
permafrost, at least in the North American Arctic, and perhaps in the world.
Samples from a 451-m-deep core hole showed that substantial amounts of
pore-space hydrate occurred at depths as shallow as 119 m. [The finding
increases existing concern that permafrost could release greenhouse gases in a
warming climate; see New Scientist, p. 16, July 1995.]
"Inversion of the Global Methane Cycle Using Chance Constrained
Programming: Methodology and Results," M. Kandlikar (Dept. Engineering, 129
Baker Hall, Carnegie Mellon Univ., Pittsburgh PA 15213), G.J. McRae, Chemosphere,
30(6), 1151-1170, Mar. 1995.
Presents a new methodology for constraining sources and sinks in mass
balances, and applies it to a global model of methane. Results show that global
budgets of methane in the literature have greater uncertainty ranges than
allowed by the constraints on its global cycle. Emissions from rice paddies and
wetlands may be lower than presented in previous budgets, a result in agreement
with recent estimates based on flux measurements. Uses sensitivity analysis to
determine key uncertain parameters in the global methane budget.
"Environmental Factors Affecting Global Atmospheric Methane
Concentrations," A.T. Smith (Dept. Geog., Univ. Delaware, Newark DE 19716),
Progress in Phys. Geog., 19(3), 322-335, Sep. 1995.
Reviews the current understanding of the role of methane in the climate
cycle, with a brief discussion of biological, chemical and physical processes
responsible for its spatial and temporal distribution in the atmosphere. The
magnitude of most methane sources is highly speculative, and their distributions
are qualitatively understood. Models of the influence of climate on biological
sources are primarily regressions on the amount of heat and water in the
environment. Process-based models are needed to address environmental conditions
unlike the present.
"Elevated Concentrations of CO2 May Double Methane Emissions from
Mires," P.R. Hutchin, M.C. Press (Dept. Animal & Plant Sci., Univ.
Sheffield, POB 601, Sheffield, UK) et al., Global Change Biology, 1(2),
125-128, Apr. 1995.
Intact cores of peat and vegetation were removed from a mire and buried in
open top chambers, where they were exposed to a 60% increase in CO2. A profound
increase in methane emissions was observed over the four-month period of study,
accompanied by a 100% increase in the rate of photosynthesis.
Guide to Publishers
Index of Abbreviations