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Volume 2 Number 8:  15 April 1999

Atmospheric CO2 Enrichment: Boon or Bane of the Biosphere?: Boon or bane?  Which is it?  Will the rising CO2 content of earth's atmosphere devastate the planet's coral reefs while it simultaneously fertilizes its forests?  Will this ongoing global environmental change be both good and bad at the same time? ...

Journal Reviews
The Increasing Amplitude of the Atmosphere's Seasonal CO2 Cycle: A Minimal Role for Global Warming: The role of Northern Hemispheric warming in causing the observed increase in the amplitude of the seasonal CO2 cycle there over the last few decades is determined to be minimal.

Changes in the Southern Greenland Ice Sheet: The mass balance of the southern portion of the Greenland ice sheet was examined over the five-year period 1993-1998.  The data suggest that the ice sheet has thickened above 2000 meters at a rate of 0.5 0.7 cm per year, while it has thinned below this level.

CO2 and Temperature: Ice Core Correlations: Contemporaneous records of atmospheric CO2 concentration and temperature derived from Antarctic ice cores examined over the last three glacial-interglacial transitions indicate that the relationship between temperature and CO2 appears to be the opposite of what is assumed in all of the climate model studies that warn of dramatic warming in response to the ongoing rise in the air's CO2 content.

The Holocene Climatic Optimum: Paradise Lost?: The authors painstakingly analyzed the composition of air bubbles trapped in glacial ice cores retrieved from the Taylor Dome area of Antarctica, determined the ages of the trapped air samples, and analyzed the isotopic composition of the carbon in the air's carbon dioxide.  They then used these data to reconstruct the history of carbon exchanges among the atmosphere, oceans and land biota over the past 11,000 years.

Temperatures of the Last Millennium: Proxy temperature data suggest that the last century was the warmest hundred-year period of the past millennium; but they provide no proof of the oft-stated claim that the warming of the last century was caused by the concomitant rise in the air's CO2 content.

Future Climate: Difficulties in Modeling Complexity: The chaotic component of earth's climate system is suggested to be potentially significant in terms of modeling climate.

Elevated CO2 and Phosphorus Uptake: Wheat seedlings grown in elevated CO2 under conditions of continuous phosphorus deficiency displayed increases in root phosphatase activity, which mineralizes organic phosphorus thereby making it available for plant use.

Elevated CO2 and Crop Residue Decomposition: Evolution of carbon from soil containing decomposing plant material was significantly less if the plant residue had been produced in an atmosphere of elevated CO2 rather than in normal air.  This observation suggests that as the CO2 content of the air increases, greater amounts of carbon will likely be stored in the soil, thereby reducing the rate at which the CO2 content of the atmosphere would otherwise rise.

Boreal Forest Plants Take Up Organic Nitrogen: In a study of nutrient uptake by trees, shrubs and grasses in a boreal forest ecosystem, it was found that organic nitrogen was taken up directly from the soil without having to undergo mineralization, thereby producing a larger, readily available pool of nitrogen to support the extra growth potential caused by the ongoing rise in the CO2 content of the air.

Anthropogenic Nitrogen Deposition has Minor Effect on Carbon Sequestration in Temperate Forests: A number of 15N-tracer studies in six European and three North American forests over periods of one to three years revealed that elevated nitrogen deposition due to human activities is "unlikely to be a major contributor" to the large CO2 sink that is implicated to exist in northern temperate forests by several other types of analysis.  This finding leaves the ongoing rise in the air's CO2 content as the prime contender responsible for this great terrestrial carbon sink.

Effects of Elevated CO2 on C3 Grass Microcosms: Implications for Global Carbon Cycling: Danthonia richardsonii microcosms exposed to elevated CO2 over a four-year period accumulated approximately 25% more carbon than microcosms exposed to ambient CO2, even when soil nitrogen was limiting to growth.  If all terrestrial ecosystems responded similarly to atmospheric CO2 enrichment, this phenomenon would account for essentially all of the "missing carbon" in the global carbon cycle.