Seed Today - Q3 2008 - (Page 68)

Global Warming? Global average temperage data are open to various interpretations What is really happening to global temperatures? Is our atmosphere getting so hot that Greenland’s ice cap is melting and sliding into the ocean? Will ice melt raise ocean levels and flood most of Florida by the end of the century? Will rising temperatures force corn and soybean seed production into northern Canada by 2058? There are data available from the National Oceanic and Atmospheric Administration’s TIROS polar-orbiting satellite that can be sliced and diced to support nearly any preconceived conclusion. Dr. John R. Christy, Distinguished Professor of Atmospheric Science and Director of the Earth System Science Center at the University of Alabama in Huntsville, has been studying atmospheric temperatures since 1987. • Global trend since Nov. 16, 1978: +0.23°F (+0.13°C) per decade. Selective sampling of Dr. Christy’s report can yield data to support contradictory conclusions. has happened since January 1998 in the northernmost third of the globe. There has been little or no net warming in the tropics over the past 28+ years, while there is very slight warming in the southernmost third of the globe. “While this warming is within the range of natural climate variation, some of the warming is consistent with human effects,” Christy says. Slow Long Term Warming Christy says from Nov. 16, 1978, through June 30, 2007, the global lower troposphere has warmed about 0.72°F. The troposphere is the lowest portion of Earth’s atmosphere. It contains almost all of its water vapor. Most of the warming that accounts for any recent warming trend, however, Climate Change Observations In his background report, Christy makes several additional observations: • Global composite temperatures Average Global Temperature (Degrees C) “[It is] impossible to say with high confidence how much human factors might influence climate change.” Dr. John R. Christy, Distinguished Professor of Atmospheric Science and Director of the Earth System Science Center at the University of Alabama, Huntsville Computer Models: It’s All About Assumptions Projected change in global temperature: Global average 1856-1999 and projected estimates to 2100 20 19 18 17 16 15 14 Assumptions #2 Assumptions #2 Assumptions #2 Assumptions #1 Each month, Dr. Christy and his colleagues summarize TIROS data and issue a global temperature report. The May 2008 report, for example, includes these global temperature fluctuations: • Global composite temp.: -0.32°F (-0.18°C) below 20-year average for May. • Northern Hemisphere: -0.09°F (-0.05°C) below 20-year average for May. • Southern Hemisphere: -0.56°F (-0.31°C) below 20-year average for May. 1860 1999 2100 By varying key assumptions about emission scenarios and the climate’s sensitivity to emissions, the projected global mean temperature increase between 1991 and 2100 varies from 1 to 4.5°C (1.8 to 8.1°F) in this computer model. Source: Climatic Research Unit, University at East Anglia, Norwich UK; “Projections: IPCC report 95.” Graph designer:Philippe Rekacewicz, UNEP/GRID-Arendal http://maps.grida.no/go/graphic/temperature_trends_and_projections 68 Third Quarter 2008 http://maps.grida.no/go/graphic/temperature_trends_and_projections

Table of Contents Feed for the Digital Edition of Seed Today - Q3 2008

Seed Today - Q3 2008 Contents Editor’s Notes Cover Feature Fred Miller, Ph.D., MMR Genetics Crosbyton Seed Company AOSCA Greg Lowry Floyd Hansmeirer AOSA/SCST According to ASTA Seedsellers, Inc. BinMaster Blake Sieker Ad Index

Seed Today - Q3 2008

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