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To: Father Terrence who wrote (49852)	8/7/1999 11:28:00 PM
From: Neocon	Respond to of 108807

Here is the summary of a report from the World Meteorological Organization: WMO Report Cites Uncertainties About Greenhouse Gas Sources, Sinks Copyright 1998 Bureau of National Affairs Daily Environment Report (February 12, 1998) GENEVA--Long-term predictions about the impact of increased greenhouse gas emissions on climate will remain seriously flawed as long as uncertainties remain about the workings of global greenhouse gas sources and sinks, according to a report from the World Meteorological Organization made available Feb. 6. The uncertainties ''present a major scientific challenge,'' the report said. There ''is much to be learned about the processes regulating the sources and sinks of greenhouse gases and about techniques to mitigate their increase,'' it added. One of the most significant gaps is an understanding of the distribution and dynamics of agriculture and forestry in both producing and absorbing gases such as carbon dioxide, nitrous oxide, and methane. The report said that ''standardized methods have been used worldwide to calculate CO2 produced by fossil fuels ... but not for agriculture and forestry. Lack of a standardized methodology and the episodicity of environmental related emissions are the principal causes of the high uncertainties of greenhouse gases from terrestrial ecosystems.'' Major Contributor Agriculture and forestry ecosystems accounted for approximately 23 percent of total CO2 equivalent greenhouse gas emissions in the 1980s, the third leading source of global warming emissions behind fossil fuel combustion and CFC releases. CFCs have higher global warming potential than CO2. Agriculture alone accounts for around 14 percent of CO2-equivalent emissions, WMO said. Methane from rice cultivation, animal waste, and biomass burning is the biggest contributor in this sector at 8 percent, with CO2 from the burning of fossil fuels from farm equipment, land cultivation and biomass burning and nitrous oxide (N2O) from cultivation, fossil fuel/biomass burning, and fertilizer use each accounting for 3 percent of the emissions total. In addition, an estimated 30 percent of the current annual increase in atmospheric CO2 is attributable to carbon loss in soil associated with deforestation and the clearing of land for agricultural and other purposes. The loss is estimated at 40 percent to 60 percent in the first meter for soil converted from forest to cropland and 25 percent to 40 percent for soil converted from grassland to cropland. Methane From Agriculture In regards to other greenhouse gases, approximately 45 percent of methane emissions are attributable to agricultural activities, while 90 percent of N2O emissions originate from nitrification and denitrification processes in soils due in part to the increased use of agricultural fertilizers. Methane emissions alone could be reduced by 10 percent to 30 percent through better irrigation and better fertilizer choice and use, and changes in rice production, WMO said. Studies concerning the impact of increased greenhouse gas concentrations on agricultural and forestry ecosystems indicate that not all the effects would be negative. Many major crops would experience stimulated growth rates, improved water efficiency, and probable increased tolerance to drought stress. A doubling of CO2 concentrations by 2100 as predicted under the ''business as usual scenario'' of the Intergovernmental Panel on Climate Change could lead to a reduction in transpiration (release of water vapor) for many crops of 23 percent to 46 percent, in effect lengthening the growing season and increasing yields for crops where moisture availability limits growth. On the other hand, lower transpiration could increase the leaf area of the crops and offset these advantages on a ground area basis. Ultimately, the report concluded, a successful greenhouse gas abatement strategy cannot rely on management techniques focusing on percentage reduction of emissions. ''It is essential that such strategies outweigh the effect of increased population and production areas such that net global rather than relative emissions be reduced,'' WMO said. ''Technologies now exist where greenhouse growth rate can be reduced.'' The report, Climate Variability, Agriculture and Forestry: An Update is available from the Secretariat of the World Meteorological Organization, 41 Avenue Giuseppe-Motta, 1211 Geneva, Switzerland.