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Volume 2 Number 14:  15 July 1999

Editorial
Why Worry About CO2?: A few decades ago we were worried about an impending ice age; and then, in less time than it took Rip Van Winkle to take a short nap, we did a full turnabout and began to worry about global warming.  Why?  Because some of the world's preeminent climate scientists told us that the ongoing rise in the air's CO2 content would dramatically exacerbate the atmosphere's natural greenhouse effect.  Which means, of course, that the scientific establishment was initially wrong about global cooling, if we assume they were subsequently right about CO2-induced global warming.  But why should we worry about global warming, CO2-induced or not-CO2-induced?...

Journal Reviews
Atmospheric CO2 Concentrations in the Middle Eocene: Analysis of boron isotope composition in planktonic foraminifera reveal that atmospheric CO2 concentrations during the middle Eocene were near present day values.

More Evidence for a Solar-Climate Link: Analysis of the near-earth interplanetary magnetic field reveals a two-fold increase in this parameter since 1900, with important implications for driving 20th century climate change.

Ruminations on a Solar-Climate Link: The author ruminates on recent advances in understanding the solar-climate link.

Does Atmospheric CO2 Enrichment Reduce Methane Emission Rates?: In a study of methane emissions from plots of rice grown under ambient and twice-ambient CO2 concentrations, it was found that, contrary to expectations, atmospheric CO2 enrichment drastically reduced methane emissions from the plots.  The probable cause of this observation was increased aeration of the soil due to CO2-induced increases in penetration of the soil by more porous roots.

Spatial and Temporal Effects of Data Gaps: Missing data, or data gaps, examined at 138 locations in the United States are shown to significantly affect the mean monthly maximum and minimum temperature.

Photosynthetic Acclimation to Elevated CO2 and Low Nitrogen Supply in Soybean: Experiments using soybeans grown in elevated CO2 with and without limiting nitrogen supply suggest that photosynthetic acclimation to elevated CO2 is caused by the accumulation of non-structural carbohydrates that cause end-product inhibition, rather than by foliar nitrogen reductions.

Responses of a Tallgrass Prairie Ecosystem to Eight Years of Atmospheric CO2 Enrichment: Tallgrass prairie ecosystems fumigated with twice-ambient atmospheric CO2 concentrations for eight years in open-top chambers produced significantly greater amounts of above- and belowground biomass than ecosystems exposed to ambient CO2 concentrations during years characterized by substantially less than average rainfall.  In addition, long-term elevated CO2 exposure did not cause the displacement of C4 species at the hand of more CO2-responsive C3 species, and thus ecosystem biodiversity was maintained.

Responses of Two Birch Species to Elevated CO2 and Soil Moisture: Seedlings of paper and yellow birch grown at 700 ppm CO2 and different soil moisture regimes for four months exhibited enhanced rates of photosynthesis and total biomass production that would tend to reinforce the current distributions of these co-occurring temperate forest species while maintaining their southernmost ranges in xeric habitats, and possibly increasing the northernmost ranges for yellow birch, thus increasing biodiversity in more mesic habitats.

Response of a Forest Ecosystem to Elevated CO2: Loblolly pine ecosystems exposed to 560 ppm CO2 for two years in a FACE experiment located in North Carolina, USA, displayed growth rates that were 26% greater than those of control ecosystems.  In addition, elevated CO2 increased ecosystem net primary productivity by 25%, thus indicating the great potential of such plantations for sequestering carbon.

Long-term Response of Trees to Elevated CO2: Atmospheric CO2 enrichment decreased the negative impacts of O3 stress on soybean yield.  Moreover, the CO2-induced yield stimulation of soybean increased with increasing O3 concentrations; and at the most stressful O3 level, the absolute yield was actually 6% higher than it was at the least stressful O3 concentration.