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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

PROFESSIONAL PUBLICATIONS...

(See also Prof. Pubs./Anthropogenic Emissions/Methane, this issue of the Global Climate Change Digest--May 1996.

Item #d96may42

"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.

Item #d96may43

"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.]

Item #d96may44

"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.

Item #d96may45

"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.

Item #d96may46

"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.