February 28, 2007
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FROM VOLUME 4, NUMBER 7, JULY 1991
THE CARBON CYCLE
"Present-Day CO2 Emissions from Volcanos," T.M. Gerlach
(Cascades Volcano Observ., USGS, 5400 MacArthur Blvd., Vancouver WA 98661), Eos,
72(23), 249, 254-255, June 4, 1991. Reviews results and implications of
past efforts to measure rates of CO2 degassing from volcanos. Makes a few
comparisons between volcanic and anthropogenic CO2 emission rates.
Nature, 351(6325), May 30, 1991.
"Etna's Greenhouse Pump," T. Gerlach (addr. immed. above),
352-353. A discussion of the role of volcanos in the global CO2 cycle, both
before and after industrialization, and of reasons for the unusually large CO2
output of Mt. Etna, documented in the following article.
"Eruptive and Diffuse Emissions of CO2 from Mount Etna," P. Allard
(Ctr. Faibles Radioactivités, CNRS-CEA, 91198 Gif-sur-Yvette, France), J.
Carbonnelle et al., 387-391.
"Enhanced Particle Fluxes in Bay of Bengal Induced by Injection of
Fresh Water," V. Ittekkot (Inst. Biogeochem., Univ. Hamburg, Bundesstr. 55,
2000 Hamburg 13, Ger.), R.R. Nair et al., ibid., 385-387.
To understand the possible effect of freshwater injection by the melting of
ice sheets during deglaciation on the uptake of atmospheric CO2, data were
collected in the Bay of Bengal, which is subject to large seasonal changes in
surface salinity. Freshwater pulses during glaciation are likely to have
resulted in short-term episodes of increased oceanic uptake of atmospheric CO2.
"Model Estimates of CO2 Emissions from Soil in Response to Global
Warming," D.S. Jenkinson (Dept. Soil Sci., Univ. Reading, Reading RG1 5AQ,
UK), D.E. Adams, A. Wild, ibid., 351(6324), 304-306, May 23,
Uses the Rothamsted model for turnover of organic matter in the soil to
calculate the amount of CO2 that would be released, a positive feedback
mechanism. If world temperatures rise by 0.03° C y-1, considered most
likely by the IPCC, the additional release of CO2 from soil organic matter over
the next 60 years will be about 19% of the CO2 that will be released by
combustion of fossil fuel with uncontrolled fuel use.
Nature, 351(6323), May 16, 1991.
"No Change Down Under," W.H. Berger (Scripps Inst. Oceanog., La
Jolla CA 92093), 186-187. Discusses implications of the following article by
Mortlock et al., which challenges the conventional view of the Antarctic Ocean
as a sink for atmospheric CO2 during past glacial periods through increased
biological activity. Without this potential regulatory mechanism for CO2, the
observed variations in atmospheric CO2 become more enigmatic.
"Evidence for Lower Productivity in the Antarctic Ocean during the Last
Glaciation, R.A. Mortlock (Lamont Geol. Observ., Palisades NY 10964), C.D.
Charles et al., 220-223.
"Atmosphere-Biosphere Exchange of Carbon Dioxide in Boreal Forests,"
G.B. Bonan (NCAR, POB 3000, Boulder CO 80307), J. Geophys. Res., 96(D4),
7301-7312, Apr. 20, 1991.
An ecophysiological model of photosynthesis and respiration by forest
ecosystems was used to examine CO2 fluxes in 23 mature boreal forests near
Fairbanks, Alaska. Simulated soil respiration, photosynthesis, decomposition,
and moss and tree productivity were consistent with observed data. Alaskan
boreal forests may play an active role in the seasonal dynamics of atmospheric
CO2 at Barrow; their metabolic activity results in a significant uptake of CO2.
Special Issue: Third International Conference on Analysis and
Evaluation of Atmospheric CO2 Data, Present and Past (Hinterzarten, Germany,
1989), I. Levin, P. Tans, Eds., Tellus, 43B(2), Apr. 1991.
Published by Swed. Geophys. Soc., c/o Editorial Off., Arrhenius Lab., S-10691
Contains 17 papers from the 83 presented. Discussions emphasized the large
remaining uncertainties about the relative amount of anthropogenic CO2 being
taken up by oceans and terrestrial ecosystems. These uncertainties are of the
order of 30% of the recent fossil fuel CO2 input into the atmosphere. The
currently operating atmospheric CO2 monitoring network (up to now mainly
designed to monitor global oceanic background conditions) has to be expanded to
include continental sites; global ocean coverage is also needed.
Comment on implications for the global climate cycle of data on
atom-bomb-derived 14C, G.H. Rau (Inst. Marine Sci., Univ. California, Santa Cruz
CA 95064), Nature, 350(6314), 116, Mar. 14, 1991.
"Spatial Variability in the Sink for Atmospheric Carbon Dioxide in
the North Atlantic," A.J. Watson (Marine Lab., Prospect Pl., W. Hoe,
Plymouth PL1 3DH, UK), C. Robinson et al., ibid., 350(6313),
50-53, Mar. 7, 1991.
In the spring of 1989, large variations in CO2 partial pressure on spatial
scales of <<100 km were observed to correlate with plankton, chlorophyll,
surface temperature and total inorganic carbon, showing that the air-sea flux is
strongly modulated by biological activity and variable on short spatial scales.
This inhomogeneity suggests that estimates of the oceanic sink for fossil fuels
inferred from existing sparse data will be subject to significant error.
"Importance of Continental Margins in the Marine Biogeochemical
Cycling of Carbon and Nitrogen," J.J. Walsh, ibid., 53-55. Sediment
trap data indicate that the annual supply of onwelling nitrate from the deep sea
to the shelves may balance the offshore flux of carbon, suggesting that the
continental margins and deep sea are equally important in the carbon and
nitrogen biogeochemical cycles.
"Carbon Dioxide and Temperature," J.B. Marston (Lab. Atomic
Phys., Cornell Univ., Ithaca NY 14853), M. Oppenheimer et al., ibid.,
349(6310), 573-574, Feb. 14, 1991. High coherence is exhibited between a
30-year record of monthly CO2 concentrations and equatorial air temperature,
suggesting a possible positive feedback mechanism for global warming.
"Distribution of Carbon Dioxide Partial Pressure in Surface Waters of
the Southwest Indian Ocean," C. Goyet (Lab. Phys. Chem. Marines, Univ.
Curie, 4 Pl. Jussieu, Tour 24-25, 75252 Paris Cedex 05, France), C. Beauverger
et al., Tellus, 43B(1), 1-11, Feb. 1991.
Describes geographical, annual and seasonal variability of the CO2 partial
pressure, including the characteristic phase change of the seasonal oceanic
surface pCO2 signal with latitude. In the southern region of the Antarctic
convergence, both the measured and calculated pCO2 values agree with those of
GEOSECS, and confirm that this region is probably a source of CO2 to the
atmosphere throughout the year.
"A Model of Carbon Storage in Forests and Forest Products,"
R.C. Dewar (Inst. Terr. Ecol., Bush Estate, Penicuik, Midlothian, EH26 0QB,
Scotland), Tree Physiol., 6(4), 417-428, Dec. 1990.
The model describes carbon storage as a function of the forest growth curve,
the rotation period and the carbon retention curves for timber products.
Relationships between management for sustained biomass yield and maximum carbon
storage are analyzed.
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