Drought and Precipitation Fluctuations in the Great Plains During the Late Nineteenth Century

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Great Plains Research: A Journal of Natural and Social Sciences Great Plains Studies, Center for February 1991 Drought and Precipitation Fluctuations in the Great Plains during the Late Nineteenth Century Cary J. Mock University of Oregon, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/greatplainsresearch Part of the Other International and Area Studies Commons Mock, Cary J., "Drought and Precipitation Fluctuations in the Great Plains during the Late Nineteenth Century" (1991). Great Plains Research: A Journal of Natural and Social Sciences. 7. https://digitalcommons.unl.edu/greatplainsresearch/7 This Article is brought to you for free and open access by the Great Plains Studies, Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Great Plains Research: A Journal of Natural and Social Sciences by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. DROUGHT AND PRECIPITATION FLUCTUATIONS IN THE GREAT PLAINS DURING THE LATE NINETEENTH CENTURY Cary J. Mock Department of Geography, University of Oregon Eugene OR 97403 Abstract. Monthly precipitation data in the Great Plains fiom the late nineteenth century (1851-1890) were compared with modem analogs. Seasonal precipitation changes were identified since 1858-1877,depending on the amount of data available, and additional droughts were inferred back to 1851. Regional droughts did not clearly fi any cycle. Precipitation during fall ad winter was less than 1951-1980 averages during most of the late nineteenth century. Wetter than modem average springs and summers occurred in the mid-1870s to the mid-1880s. Relationships of these conditions to changes in mid-tropospheric circulation are suggested Results from this study can be used for verification of dendroclimatic reconstnrctions and assessment of climatic impact on settlement. Recurring drought has had marked economic and agricultural consequences in the Great Plains region of the United States since Euro-American settlement began in the latter half of the nineteenth century (Hecht 1983; Wilhite 1983). The drought of 1988-1989 in the northern and eastern portions of the Plains ranks in the top five most severe droughts of the twentieth century (Trenberth et al. 1988, National Climate Program Office 1988). Severe droughts similar in magnitude, spatial extent, and duration to those of the late-1980s and the 1930s may occur more frequently in a future of globally-warmer climate and dramatically alter the character of human life in the Plains (Borchert 1971; Bowden 1977). Substantial research has been conducted on past, present, and future climates of the Great Plains. Scholars have studied the mechanisms of Great Plains climatology (Borchert 1950; Klugman 1978; Barry 1983; McGregor 1985; Rosenberg 1986), attempted to predict future climates (Manabe and Wetherald 1986), and assessed impacts of future droughts on society (Wilks 1988). All of these works focus on and utilize climatic information within the twentieth century, since most continuous meteorological records extend back only to about 1895. These records have limitations in providing information on climatic variability. For example, Nineteenth-Century Drought 27 some scholars have inferred periodic cycles of severe drought of approximately 16-22 years due to solar activity (Mitchell et al. 1979; Currie and O'Brien 1990). These cycles have been disputed (Karl and Koscielny 1982), in part because the meteorological record is limited. A better understanding of climatic variability and its impact on society can be achieved by reconstructing climatic conditions of the Great Plains in the nineteenth century. An understanding of how climate-society relationships have changed through time may enable assessment on the impact of future severe drought (Warrick and Bowden 1981). To date, little is known about nineteenth-century Great Plains climate. The Great Plains was perceived as a dry, barren land called the "Great American Desert" prior to 1860 (Allen 1985). The western barrier to the agricultural frontier, separating the humid east from the arid west, was between the 98th and 100th meridians (Smith 1947). Following the Civil War, the livestock industry moved northward from Mexico into the Plains (Allen 1985), and Euro-American settlement expanded westward from the east (Wishart 1987). By the late 1870s and early 1880s, thousands of settlers had traveled beyond the 98th meridian (Baltensperger 1979; Wishart 1987). The Great Plains was then perceived as the Garden of the world (Allen 1985). The Garden Myth was related to the belief that increased irrigation caused permanent increases in Great Plains precipitation (Smith 1947). The advent of new technology such as barbed wire, the steel windmill, and the railroad made settlement in the Great Plains possible, but an abnormally wet climate may have also played a significant role. However, drought may have occurred occasionally and locally. The cattle industry declined during the mid-1880s (Wishart 1987), perhaps related to reduced precipitation during spring and summer that decreased the amount of forage (Albertson et al. 1957). The influx of settlers to the Great Plains was reduced at times because of drought (Baltensperger 1979). An accurate climate reconstruction is the first step for answering questions about the impact of climate on settlement and environmental perception during the nineteenth century (Lawson 1974; Lawson and Stockton 1981). Climate cannot be inferred from historical non- meteorological sources because the reconstruction would lead to circular reasoning about historical climate impact assessment (Kates 1985). Much of the climate record for the Great Plains prior to 1895 has been reconstructed from tree rings (Weakly 1943; Harper lW, Lawson 1974; Lawson et al. 1980, Duvick and Blasing 1981; Stockton and Meko 1983; Blasing and Duvick 1984, Stahle and Herr 1984, Meko et al. 1985; Blasing et al. 1988, ~tahleand Cleaveland 1988). Although tree rings are a useful proxy data source, dendroclimatic implications must be cross- checked with other proxy evidence for verification. Furthermore, many 28 Great Plains Research Vol. 1 No. 1 parts of the Great Plains are devoid of trees more than one hundred years old, making dendroclimatic applications impossible. A network of meteorological stations was established in the Great Plains in the mid-nineteenth century, well before the establishment of the United States Department of Agriculture in 1891 (Darter 1942; Bates and Fuller 1986). Wahl and Lawson (1970) analyzed 20-year anomalies of precipitation and temperature for 1850-1870, but no other studies have utilized these data. Although these instrumental data are not as reliable as modem weather data, they can be used for studying past climatic trends through careful analysis and screening (Roden 1%6, Bradley 1976). This study utilizes monthly precipitation records from 1851-1890 to detect drought in the last half of the nineteenth century. The possibility of drought cycles is also discussed. Nineteenth century seasonal climatic data were also compared with modern climatic normals (1951-1980) to detect temporal trends. The period 1951-1980 was chosen as the climatic normal because many modern meteorological stations provide records near nineteenth-century stations and can serve as analogs for comparisons. The time period excludes the droughts of the 1930s and the 1980s, which may present misleading representations of climatic normals. Study Area And Data The western Great Plains comprises the portions of Montana, Wyoming, Colorado, and New Mexico east of the Continental Divide, and Texas northward of San Antonio. The Continental Divide is the physio- graphic boundary between the Great Plains and Rocky Mountains. The eastern Great Plains consist of North Dakota, South Dakota, Nebraska, Kansas, and Oklahoma (Figure 1). The eastern border of the study area corresponds approximately to the 98th meridian. Detailed descriptions of the history of nineteenth century instrumental data have been provided by Lawson (1855), Darter (1942), Lawson (1974), and Bradley (1976), and only a brief summary is provided here. Many problems in the nineteenth-century data set and its comparison with modem data are evident. Despite these problems, previous investigations show that signs of climate anomaly (Wahl and Lawson 1970; Bradley 1976) and occurrences of extreme weather events such as drought and flood (Lawson 1974) can be inferred accurately. Recognition of problems in the data permits the construction of a methodology to work through them. A network of meteorological stations existed west of the Missouri River by 1860, but they were few in number and limited to eastern Nebraska, eastern Kansas, and Texas. Throughout the nineteenth century, many stations operated for less than five years (Table 1). Many stations Nineteenth-Century Drought Continental 0 100 200 -MILES Figure 1. Locations of nineteenth-century meteorological stations in the study area. Station names are given in Table 1. Great Plains Research Vol.1 No.1 moved locally, and some moves likely went unrecorded (Bradley 1976). Station histories that have numerous gaps most likely indicate numerous moves. In order to retain a basis for comparison of temporal trends of precipitation, only stations with histories having a minimum of three consecutive years were used. Monthly precipitation data

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