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Volume 1 Number 3:  15 October 1998

CO2 and Global Change: An Issue of Manifold Dimensions: In reviewing the "hits" received by our website over the past month, it is clear that concerns about climate currently dominate the public's interest in CO2 and potential global change.  In addition, as was discussed in our first editorial, global warming per se seems to lie at the heart of the debate that swirls about this subject, driven largely by predictions of its consequences, which are typically portrayed as negative.  Unfortunately, it is this last and very limited perspective that provides the bulk of the grist for the political millstones that grind on ever so relentlessly towards a global agreement to deal with the phenomenon that set the whole process in motion: the rising CO2 content of earth's atmosphere...

Journal Reviews
What Causes Heinrich Events?: Massive discharges of icebergs into the North Atlantic Ocean called Heinrich events may be triggered by ice-load-induced earthquakes instead of variations in orbital parameters, as currently believed, introducing a previously unrecognized impetus for climate change into the already ultra-complicated problem of predicting earth's climate future.

Recent Trends in Southern Greenland Ice Sheet Thickness: Radar altimeter measurements of the surface of the Greenland ice sheet suggest that it rose by approximately 2 cm per year between 1978 and 1988, while additional data suggest that the rise may have been as much as three times greater.

Basal Melting of a West Antarctic Glacier: Satellite radar measurements of a West Antarctic glacier indicate a fast retreat of its grounding line over the period 1992 to 1996. This fast retreat may have implications for the long-term stability of the West Antarctic Ice Sheet, but linking it to the ice sheet's demise may be premature.

The Geologic Influence on a West Antarctic Ice Stream: Aerogeophysical data were collected and used to investigate the dynamics of a fast moving West Antarctic ice stream. Its movement was found to be predominantly determined by features of the sedimentary basin below it, greatly moderating climatic influences.

West Antarctic Ice Sheet Stability: A major review of the scientific literature relative to the future stability of the West Antarctic Ice Sheet is able to conclude nothing of substance.

Effects of Low and High CO2 on Soybean Growth: Soybean plants grown for an entire season in growth chambers receiving atmospheric CO2 concentrations ranging from 160 to 990 ppm exhibited linear increases in total nonstructural carbohydrates in all vegetative tissues, leading to corresponding increases in aboveground biomass production.

Atmospheric CO2 Effects on Spruce Trees: Experiments performed on individual branches of 30-year-old Norway spruce trees revealed that a near-doubling of the air's CO2 content enhanced rates of light-saturated net photosynthesis by 50-55% and increased foliage concentrations of nonstructural carbohydrates by 33%.

Changes in Beech Tree Water-Use Efficiency During the Past Century: The intrinsic water-use efficiency of two differentially-managed beech forests in north-eastern France increased, on average, by 33% during the past century.  This value is consistent with other studies that have reported increased water-use efficiencies of trees in response to rising levels of atmospheric CO2.

Effects of CO2 on a Tropical Rainforest Mesocosm: A 72% increase in atmospheric CO2 enhanced the carbon exchange rate of a synthetic rainforest ecosystem by 79%, indicating that these highly productive ecosystems will likely become even more productive as the CO2 content of the air continues to rise.

Elevated CO2 and Plant Defense: Eucalyptus seedlings exposed to elevated CO2 (800 ppm) for six months exhibited partial photosynthetic down regulation.  Despite this phenomenon, CO2-enriched trees exhibited about twice the biomass production of trees grown at 400 ppm CO2, regardless of soil nitrogen fertility.  Because leaf nitrogen content decreased by about 27% at high CO2, down regulation allowed for the mobilization of nitrogen away from photosynthesis and into the defensive compound prunasin to provide plants in elevated CO2 with the same protection as plants in ambient CO2.