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Volume 4 Number 22:  30 May 2001

Temperature Record of the Week
This issue's Temperature Record of the week is from Douglas, Arizona. Visit our U.S. Climate Data section to plot and view these data for yourself.

Current Editorial
Trees: The Incredible Shrinking Carbon Sinks: Two new scientific studies, as well as a host of popular press reports, suggest that the planting of forests – a strategy long touted by the United States as an effective means for sequestering carbon – can no longer be considered a viable way to remove CO2 from the atmosphere.  A critical analysis of these studies, however, raises several serious questions about this conclusion, which is beginning to look like an unjustified rush to judgment.

Subject Index Summaries
Grasslands (Photosynthesis): A review of the recently published literature suggests that earth’s grassland species will respond positively to increases in the air’s CO2 content by exhibiting enhanced rates of photosynthesis, even under unfavorable growing conditions characterized by water stress, poor soil nutrition, elevated air temperature and herbivory.

Solar Climate Effects: In striking contrast to atmospheric CO2 concentration, the variable sun shows its influence on earth’s climate in a number of scientific studies of the current interglacial period.

Current Journal Reviews
Cosmic Rays and Climate Change: Empirical evidence reveals the existence of a solar-induced feedback phenomenon that may explain 20th century warming.

Additional Evidence of a Solar-Climate Link: Unlike the dilemma we face when attempting to determine cause and effect in cases of concomitant changes in atmospheric CO2 and climate, when solar activity and climate vary in phase with each other, it is clear that solar activity is the independent variable and that climate is the responding or dependent variable.

Elevated CO2 Increases Photosynthesis and Water-Use Efficiency in Peas: Peas grown at an atmospheric CO2 concentration of 700 ppm exhibited photosynthetic rates that were 53% larger than those of control plants without displaying any signs of photosynthetic acclimation.  In addition, elevated CO2 increased total plant biomass by an average of 15% and enhanced plant water-use efficiency by 27%.

Impacts of Elevated CO2 on the Rhizosphere: A review of the recent literature demonstrates that atmospheric CO2 enrichment tends to increase plant photosynthesis and growth, which often leads to increased carbon inputs to soils.  Such enhancements of soil carbon generally stimulate the growth and activities of soil microorganisms, some of which positively feedback to increase plant photosynthesis and growth, thus amplifying the CO2-induced plant growth response.

Elevated CO2 Stimulates Growth in Young Scots Pine: After enriching the air with an extra 400 ppm of CO2 for three years, Scots pine seedlings rooted in the ground within open-top chambers responded by increasing their total biomass by 55% and their root biomass by more than 150%, in spite of their being rooted in a relatively nutrient-poor soil.