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Volume 2 Number 2:  15 January 1999

Something Old, Something New: As we commence a new year of work at the Center for the Study of Carbon Dioxide and Global Change, we thought we would reflect on a few of the major science stories we covered in 1998, as well as speculate on where the science of CO2 and global change is likely to take us in 1999.

Journal Reviews
There is a Human Influence on Climate: A study of temperatures in large industrial cities in India suggests that the cooling influence of urban-produced particulate matter is over-powering natural warming and urban heat island effects.

There isn't a Human Influence on Climate: Proxy temperature data for Scandinavia reveal that summer temperatures there have oscillated throughout the last 10,000 years in apparent response to changes in solar irradiation.

The Natural Variability of Climate: A 500-year global climate model simulation suggests that natural variability within the actual climate system may explain nearly all global temperature fluctuations over the past millennium.

Warmer Temperatures at Lower CO2 Concentrations: Proxy temperature and precipitation data from a lake-sediment core in Morocco indicate that both winter and summer temperatures there were "4C warmer than the present" at a time when earth's atmospheric carbon dioxide concentration was approximately 100 ppm less than it is today.

Effects of Elevated CO2 on Fungal Infection of an Annual California Grass: Four months of atmospheric CO2 enrichment in open-top chambers increased percent arbuscular infection of roots and the infection intensity of all but the youngest roots of Bromus hordeaceus, despite the fact that percent root length colonized remained unaffected.

Effects of Elevated CO2 on Fungi: In a literature review of arbuscular mycorrhizal fungi responses to atmospheric CO2 enrichment, the authors determined that when increased root colonization occurs in response to elevated CO2, it acts synergistically with the elevated CO2 to increase plant growth.

Interactive Effects of CO2 and Fungi on Sagebrush: In a study of sagebrush plants inoculated with four different species of fungi, it was found that a doubling of the air's CO2 content significantly enhanced the development of fungal structures that facilitate internal and external nutrient transfer, which led to a 35% increase in sagebrush root biomass, thereby significantly increasing its prospects for survival in nutrient-poor environments and during periods of drought.

Interactive Effects of CO2 and Mycorrhiza on a Perennial Herb: In a three-month study of Plantago lanceolata plants inoculated with mycorrhizal fungi, it was found that a 54% increase in the air's CO2 content significantly enhanced root development and fungal colonization of roots.  This stimulation, in turn, led to greater uptake of mineralized phosphorous, which played a major role in enhancing total biomass production in plants grown in elevated CO2.

Effects of CO2 on Microbial Community Structure: Six or 18 weeks of atmospheric CO2 enrichment did not affect rhizosphere microbial community structures of ryegrass or wheat microcosms, indicating that the increasing CO2 content of the air will maintain soil microbial biodiversity beneath these species.