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Volume 2 Number 17:  1 September 1999

Editorial
Science and Trust: Are They Compatible?: A newly recognized consequence of the aerial fertilization effect of atmospheric CO2 enrichment has been demonstrated to enhance the mass and stability of small aggregates in the soils of three intensively-studied natural ecosystems, thereby improving soil structure and lessening the potential for soil erosion via the negative effects of wind and rain.

Journal Reviews
Increasing Weather Extremes: Real or Imagined?: The authors analyze empirical data related to historical trends of several different types of extreme weather events and their societal impact.  They found that although "most measures of the economic impacts of weather and climate extremes over the past several decades reveal increasing losses," trends in the weather and climate extremes themselves "do not show comparable increases with time."

More Evidence for Future CO2-Induced Global Cooling: A case is made for the final outbust drainage of glacial lakes Agassiz and Ojibway being the cause of the dramatic cooling event experienced by land surrounding the North Atlantic some 8200 years ago.  The same mechanism that operated to cool the climate at that time has recently been invoked to predict a CO2-induced cooling of our global climate in the near future, casting doubt on the likelihood of the host of catastrophic heat-related consequences typically predicted to result from continued global warming.

The Opposing Impacts of Intensified Human Activities: Surveys of bird populations by the British Trust for Ornithology reveal that farmland species have declined dramatically since 1968, but that more generalist species have increased substantially over the same period.  The former unfortunate phenomenon is attributed by the authors to intensified farming practices, while the latter beneficent observation in ignored.  Feeling that good news is as significant as bad, we speculate that the increase in generalist bird species is a consequence of the ongoing rise in the air's CO2 concentration, which stimulates the production of both habitat and food in the natural environment.

CO2-Induced Global Warming: Pro and Con: This comment on an EOS Forum article by S. Fred Singer, to which Singer briefly replies, continues to explore the question of possible linkages between human activities and global climate change.

Three Centuries of Ground Surface Temperature Change in Southern Canada: A three-hundred-year record of proxy temperatures in southern Canada reveals the existence of a 3C temperature increase that occurred before the major modern buildup of atmospheric greenhouse gases.

Response of Mango Trees to Elevated CO2: After 12 months of atmospheric CO2 enrichment, mango trees grown at 700 ppm CO2 displayed total dry weights that generally were larger than those of plants grown at ambient CO2, in spite of the fact that they exhibited partial photosynthetic acclimation to elevated CO2.  Foliar concentrations of mineral elements generally were reduced by atmospheric CO2 enrichment, most likely due to a dilution effect resulting from greater leaf dry weight.

Response of Mangroves to Elevated CO2, Humidity, and Salinity: After 14 weeks of exposure to an atmospheric CO2 concentration of 700 ppm, two Australian mangrove species exhibited increases in net photosynthesis and relative growth rates when grown at a salinity approximating 25% seawater, but not 75% seawater.

Elevated CO2 Reduces Maintenance Respiration in Roots: Total and maintenance respiration rates of five-month old western hemlock roots decreased exponentially with increasing soil CO2 concentration, thus increasing photosynthetic efficiency and the potential for carbon sequestration.

Effects of Elevated CO2 and Mycorrhizal Colonization on Photosynthesis of Plantago lanceolata: Plantago lanceolata inoculated with an arbuscular mycorrhizal fungus and grown in open-top chambers for 100 days at an atmospheric CO2 concentration of 600 ppm displayed higher photosynthetic rates than plants grown at ambient CO2 or at elevated CO2 without fungal inoculation.  In addition, with fungal inoculation, CO2-enriched plants did not display any signs of photosynthetic acclimation to elevated CO2, based on photosynthetic measurements made at CO2 concentrations ranging between 0 and 1000 ppm.

Effects of Long-Term CO2 Enrichment on Fungal Root Colonization in Grasslands: Long-term atmospheric CO2 enrichment of natural grasslands significantly impacted fungal root colonization variables and fungal composition in a plant species dependent manner.  Most notable was a significant increase in the percent colonization of arbuscules, which persisted in both grassland types even after six years of CO2 enrichment.