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 4, NUMBER 3, MARCH 1991
GLOBAL CARBON CYCLE
"Isotopic Composition of Atmospheric CO2 Inferred from Carbon in C4
Plant Cellulose," B.D. Marino (Dept. Earth Sci., Harvard Univ., Cambridge
MA 02138), M.B. McElroy, Nature, 349(6305), 127-131, Jan. 10,
Shows that carbon in C4 plants preserves an isotopic record of the CO2 used
in photosynthesis, and that data for the maize plant yield results for the
isotopic composition of atmospheric CO2 that are consistent with measurements of
modern air trapped in polar ice. Studies of intact and fossil (dating to 1500
A.D.) C4 material provide a way to extend the isotopic record of atmospheric CO2
into the past, complementing data from other sources.
"Air-Sea Gas Exchange in Rough and Stormy Seas Measured by a
Dual-Tracer Technique," A.J. Watson (Plymouth Marine Lab., Prospect Pl.,
West Hoe, Plymouth PL1 3DH, UK), R.C. Upstill-Goddard, P.S. Liss, ibid.,
Reports first results from the application of a tracer technique which
enables accurate measurements to be made over periods of 24-72 hours, including
the first determination of gas exchange in stormy conditions. Results suggest
lower CO2 exchange rates than those obtained by 14C budgeting, and favor recent
lower estimates of the global oceanic sink for anthropogenic CO2.
"Arctic Lakes and Streams as Gas Conduits to the Atmosphere:
Implications for Tundra Carbon Budgets," G.W. Kling (Ecosyst. Ctr., Marine
Biol. Lab., Woods Hole MA 02543), G.W. Kipphut, M.C. Miller, Science,
251(4991), 298-301, Jan. 18, 1991.
Measurements of the partial pressure of CO2 in 29 aquatic ecosystems across
arctic Alaska showed that in most cases CO2 was released to the atmosphere. This
CO2 probably originates in terrestrial environments, by erosion of particulate
carbon plus groundwater transport of dissolved carbon. If this mechanism is
typical of that of other tundra areas, then current estimates of the arctic
terrestrial sink for atmospheric CO2 may be 20% too high.
"Long-Term Changes in Amplitudes of Atmospheric CO2 Concentrations at
Ocean Station P and Alert, Canada," Y.-H. Chan, C.S. Wong, Tellus,
42B(4), 330-341, 1990. (See Prof. Pubs./Trend Analysis, this Global
Climate Change Digest issue--Mar. 1991.)
"Vegetation an Unlikely Answer," W.H. Schlesinger (Dept. Bot.,
Duke Univ., Durham NC 27706), Nature, 348(6303), 679, Dec.
Discusses recent work on the role of land, plants and soils in the uptake of
enhanced CO2, such as that by Adams (next entry). Because of future human
activity, the terrestrial biosphere is unlikely to act as a significant future
"Increases in Terrestrial Carbon Storage from the Last Glacial
Maximum to the Present," J.M. Adams (Dept. Bot., Univ. Cambridge, Downing
St., Cambridge CB3 2EA, UK), H. Faure et al., ibid., 711-714.
Presents palynological, pedological and sedimentological evidence indicating
that the amount of carbon in vegetation, soils and peatlands may have been
smaller during the Last Glacial Maximum (LGM) by about 1.3x1012 tons, and may
have more than doubled since then. Oceanic CO2 reservoirs seem to be the only
possible source of present levels of this large quantity of carbon. The
terrestrial vegetation and soil carbon reservoirs should be seen as a factor
tending to damp the oceanically driven glacial-interglacial CO2 fluctuations
during the LGM.
"Evidence from Chronosequence Studies for a Low Carbon-Storage
Potential of Soils," W.H. Schlesinger (Dept. Bot., Duke Univ., Durham NC
27706), Nature, 348(6298), 232-234, Nov. 15, 1990.
Although Pentice and Fung have suggested that terrestrial vegetation and
soils would act as a large sink for atmospheric CO2 if its concentration were
twice the present level, found that production of refractory humic soil
substances sequesters only about 0.4x1015 g C yr-1 from the atmosphere, or just
0.7% of terrestrial net primary production. Moreover, the loss of humic
materials from cultivated lands is greatly in excess of the rate of formation of
humus in undisturbed lands, transforming the soil pool from a small sink to a
large source of atmospheric CO2.
"Hydroxyl Radical Photoproduction in the Sea and Its Potential
Impact on Marine Processes," K. Mopper (Chem. Dept., Washington State
Univ., Pullman WA 99164), X. Zhou, Science, 250(4981), 661-664,
Nov. 2, 1990.
Photochemical production rates and steady-state concentrations of OH
radicals were measured in sunlight-irradiated seawater. Found that dissolved
organic matter is degraded more readily by OH and its daughter radicals in the
deep sea than in open-ocean surface water. This result may bear in part on major
discrepancies among current methods for measuring dissolved organic carbon in
"Intensification of Recycling of Organic Matter at the Sea Floor
near Ocean Margins," R.A. Jahnke (Skidway Inst. Oceanog., POB 13687,
Savannah GA 31416), C.E. Reimers, D.B. Craven, Nature, 348(6296),
50-54, Nov. 1, 1990.
A study of benthic exchange and metabolism performed off the California
continental shelf indicates that across the northeast Pacific, half the input of
organic carbon to the sea floor occurs within 500 km of the continental shelf.
Measured rates of benthic carbon oxidation exceed the fluxes of organic carbon
determined from previous sediment-trap studies by a factor of three.
"Estimating Atmospheric CO2," N.J. Shackleton (Godwin Lab. Quat.
Res., New Museums Site, Free School Ln., Cambridge CB2 3RS, UK), ibid.,
347(6292), 427-428, Oct. 4, 1990. Discusses a new approach to estimating
the history of CO2 partial pressure in the ocean surface waters, proposed by
Jasper and Hayes (next entry). It should extend the CO2 record well beyond the
start of the ice-core record, and elucidate changes in the dynamic equilibrium
of CO2 between the atmosphere and the sea surface.
"A Carbon Isotope Record of CO2 Levels during the Late Quaternary,"
J.P. Jasper (Biogeochem. Labs., Indiana Univ., Bloomington IN 47405), J.M.
Hayes, ibid., 462-464.
A signal related to atmospheric CO2 levels, seen in the isotope record of a
hemipelagic sediment core, can be correlated with that of the Vostok ice core.
This should permit extrapolation of CO2 records to times earlier than those for
which ice-core records are available.
"Dynamics of Dissolved Organic Carbon in the Northwestern Indian
Ocean," M.D. Kumar (Nat. Inst. Oceanog., Dona Paula, Goa 403 004, India),
A. Rajendran et al., Marine Chem., 31, 299-316, 1990. Reports
non-conservative behavior of DOC in the northwestern Indian Ocean, which
contrasts with earlier reports of conservative behavior, by studying this
parameter together with other carbon and nitrogen components.
"Bombs and Ocean Carbon Cycles," J.R. Toggweiler (Geophys.
Fluid Dyn. Lab., Princeton Univ., POB 308, Princeton NJ 08542), Nature,
347(6289), 122-123, Sep. 13, 1990. Discusses work by Druffel and
Williams that supports the dissolved organic pathway of carbon transport to the
deep ocean. (See next entry.)
"Identification of a Deep Marine Source of Particulate Organic Carbon
Using Bomb 14C," E.R.M. Druffel (Woods Hole Oceanog. Inst., Woods Hole MA
02543), P.M. Williams, ibid., 172-174.
The influx of radiocarbon 14C from earlier nuclear bomb tests was evaluated
by radiocarbon dating of pelagic organisms in the North Pacific. The per mil
deviation from the `standard' activity of nineteenth century wood (delta 14C)
was found to have a significant gradient with depth, an observation that would
not be expected according to long-standing assumptions about carbon cycling in
the water column. Discusses the roles of dissolved organic carbon and sinking
particulate organic carbon.
"Dissolved Organic Carbon in the Ocean," E.A. Romankevich
(Shirshov Inst. Oceanol., USSR Acad. Sci., 23 Krasikova, SU-117218, Moscow,
USSR), S.V. Ljutsarev, Marine Chem., 30(1-3), 161-178, Aug.
1990. Soviet investigations of DOC in the Peruvian upwelling area, the Bay of
Bengal, the Philippine Sea and the Antarctic area are summarized, discussed and
compared to results of Sugimura and Suzuki for the Philippine Sea.
"Carbon Balance in Tussock Tundra under Ambient and Elevated
Atmospheric CO2," N.E. Grulke,...W.C. Oechel (Biol. Dept., San Diego State
Univ., San Diego CA 92182) et al., Oecologia, 83(4), 485-494,
Whole ecosystem CO2 flux was measured in situ on the North Slope of
Alaska. Elevated CO2 caused greater carbon acquisition and there was a net loss
of CO2 under ambient conditions at this upland site. The measurements indicate a
current loss of carbon, possibly the result of recent climatic changes, and
suggest little if any long-term stimulation of ecosystem carbon acquisition by
increases in atmospheric CO2.
"Biological Production off Southern California Is Linked to Climatic
Change," C.B. Lange (Scripps Inst. Oceanog., Univ. Calif. Geol. Res. Div.,
La Jolla CA 92093), S.K. Burke, W.H. Berger, Clim. Change, 16(3),
319-329, June 1990.
Decreases in the flux of diatoms in the last few decades, indicated by
marine laminated sediments, are interpreted in terms of mean temperatures and
the strength of the Aleutian Low and associated oceanic mixing and upwelling.
The possibility that low coastal production could provide positive feedback to
global warming through reduced CO2 uptake is considered.
Guide to Publishers
Index of Abbreviations