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Volume 3 Number 9:  1 May 2000

Editorial
Thank God, He's Smarter Than Us (And Al Gore Too!): In the results of a study of the effects of industrial particulate pollution on clouds and rain-producing processes, we find evidence of an intricate system of checks and balances in earth's climate system that may well "save us from ourselves" with respect to potential human-induced global warming.

Subject Index Summaries
Carbon Sequestration
     Agricultural Lands

Chlorophyll

Deep Water Formation

Extraterrestrial Climatic Effects

Feedback Factors

Natural Variability

Rapid Climate Change

Volcanic Eruptions

Journal Reviews
Extreme Weather Events: Are They Increasing in Frequency or Intensity?: A review of what we know about trends in extreme weather events suggests that for the world as a whole there are no trends.

Why Are the Impacts of Extreme Weather Events Increasing?: Although United States insurance losses resulting from extreme weather and climate events have risen significantly over the past half-century, this phenomenon is shown to be wholly due to changes in inflation, liability, land and property values and wealth.

Climate Variability and Flood Frequency: A study of flood flow histories of the Upper Mississippi, Lower Missouri and Illinois Rivers reveals a host of complexities with respect to both trends and their potential causes.

Will Global Warming Raise or Lower Global Sea Level?: The author reviews the status of our knowledge of the mass balances of the Greenland and Antarctic ice sheets, concluding that we do not know what their current long-term trends are and that we also do not know what their net response to global warming will be.

Penguins and Polar Climate: The past several decades of warming on the western Antarctic Peninsula have resulted in increased primary productivity and greater populations of more species of penguins.

Photosynthetic Response of Eucalyptus to Elevated CO2 and Water Stress: Eucalyptus seedlings grown for eight months at an atmospheric CO2 concentration of 800 ppm exhibited photosynthetic rates that were 120 and 12% greater than those of seedlings grown at 380 ppm CO2 under well-watered and water-stressed conditions, respectively.  Thus, the air's rising CO2 content will likely stimulate photosynthesis in this woody species, regardless of soil moisture content.

Effects of Elevated CO2 and Ozone on Oak Trees: Various experiments performed on young oak, chestnut, and beech trees demonstrate that elevated CO2 induces stomatal closure in a species-dependent manner.  These CO2-induced reductions in stomatal conductance reduce the amount of tropospheric ozone uptake, which decreases the deleterious effects of this harmful air pollutant on plant growth and development.

Effects of Elevated CO2 on Plant-Fungal-Soil Relationships in Birch: In a short three-month study, birch seedlings grown in elevated CO2 accumulated less biomass than their ambiently-grown counterparts, regardless of fungal inoculation.  However, elevated CO2 significantly increased soil carbon contents and enabled fungal mycelia to grow more robustly and associate with 30% more soil volume than in the ambient CO2 treatment.  Thus, had the experiment been of longer duration, it is likely that increased nutrient acquisition by CO2-enriched mycelia would have facilitated greater biomass production in the CO2-enriched birch seedlings.

Effects of Elevated CO2 and Genotype on Leaf Quality of Lotus corniculatus and the Larval Development of the Common Blue Butterfly: Atmospheric CO2 enrichment increased starch and tannin contents in leaves of four Lotus corniculatus genotypes, decreased foliar cyanoglycosides, and did not affect leaf water, sugar, protein, and nitrogen contents.  Collectively, these changes in leaf chemistry increased the palatability of leaves to the Common Blue Butterfly larvae, which consumed greater amounts of CO2-enriched, rather than ambiently-grown, leaves.  In addition, CO2-induced changes in leaf chemistry positively influenced larval development by reducing mortality rates, increasing larval biomass, and quickening larval maturation.  Thus, it is likely that the rising CO2 content of the air will continue to favor the persistence of the Common Blue Butterfly in ecosystems where Lotus corniculatus is present.

Response of Tall Fescue and its Associated Aphid Populations to Elevated CO2: Tall fescue plants inoculated with aphids and fumigated with an atmospheric CO2 concentration of 700 ppm for nine weeks exhibited 37% more dry matter production than inoculated plants grown at ambient CO2 concentration.  In addition, CO2-enriched plants contained 322% fewer total aphids than plants grown at ambient CO2.