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Pastimes : Let's Talk About Our Feelings!!! -- Ignore unavailable to you. Want to Upgrade?

To: James R. Barrett who wrote (48853)	8/4/1999 1:29:00 AM
From: greenspirit	Respond to of 108807

James, Article...Good News in the Heartland... In a recent book entitled Does the Weather Really Matter: The Social Implications of Climate Change, author William James Burroughs presents historical data from the state of Kansas showing a linkage between summer rainfall and summer temperature. The point is made that the most severe droughts of this century have been associated with the hottest summers. Obviously for a state with a strong agricultural base, hot and dry is a very bad combination. We all realize that droughts have impacted Kansas many times in the past, and that the droughts will occur in the future. However, given that most theoretical climate models predict that as greenhouse gases increase in atmospheric concentration, Kansas will experience higher temperatures, higher evaporation rates, lower soil moisture levels, and a higher frequency, intensity, and duration of droughts, some are concerned for the climate future of the Jayhawk state. Following the lead of Burroughs, we examined the historical climate records for Kansas to determine how the climate of the state has changed during a period of time when greenhouse gases concentration increased exponentially. We downloaded the monthly climate divisional temperature, precipitation, and Palmer Drought Severity Index (PDSI) values for all nine evenly-spaced climate divisions in Kansas from January, 1895 to December, 1998. These data are available from the National Climatic Data Center, they are widely-used in climate research, and they have undergone extensive quality control procedures. The areally-averaged temperature and precipitation data came from the daily observations made at stations throughout the state; the PDSI values are derived from these primary variables. More specifically, the PDSI is based on the moisture balance resulting from precipitation input to a surface and losses driven by potential evapotranspiration, which is dependent upon temperature. Man-made changes such as increased irrigation are not included in the computation of this index. The index generally ranges from -6 to +6, with negative values denoting dry spells, and positive values indicating wet spells. PDSI values 0 to -0.5 = normal; -0.5 to -1.0 = incipient drought; -1.0 to -2.0 = mild drought; -2.0 to -3.0 = moderate drought; -3.0 to -4.0 = severe drought; and greater than -4.0 = extreme drought. Similar adjectives are attached to positive values for wet spells. A plot of mean annual temperatures for Kansas from 1895 to 1998 is shown in Figure 1. The plot shows no change in mean temperature from 1895 to 1915, a highly statistically significant warming from 1915 to 1935, and a slight cooling from 1935 to 1998. Despite the increase in greenhouses gases over the past half century and the model predictions for substantial warming, Kansas has cooled a bit rather than warmed! We computed the linear change in temperature for each month from 1895 to 1998 and found cooling in four months (January, August, September, November) and warming in eight months. The only trend that could be judged statistically significant is a long-term warming pattern found in February. Given that February's average temperature in Kansas is less than 33°F, it is highly doubtful than residents of the state would be upset to learn that a small warm-up has occurred in this one month. A plot of total annual precipitation shows variability from year to year, and a small upward drift over the 104 years of record (Figure 2). Just as suggested by Burroughs, the precipitation values are indirectly related to temperatures; higher temperatures are related to drier years and cooler temperatures are related to wetter years. Finally, a plot of the PDSI values shows the prominent droughts in the mid-1930s and mid-1950s (Figure 3). However, there is an increase in PDSI over the entire period showing a slight trend toward more moist conditions. Kansas is a speck on the surface of the earth covering only 0.1 percent of the planet's total area. The state is largely rural and therefore urban heat island problems should be at a minimum. Kansas is located in the heart of a continent where greenhouse warming should be pronounced according to the numerical climate models. Also, there is no large sulfate emission source upwind to reduce the warming. Despite the predictions for warming and more droughts, Kansas has seen cooling over the past half century, no change in precipitation, and a slight trend away from drought.