Fig. 1-1: Agriculture-related vegetation types (irrigated crops, dryland crops, and grasslands) cover most of the Great Plains region. There are also many federal lands located throughout the Great Plains region. (Modified from Kittel and Ojima landcover maps derived from the Loveland (1991) AVHRR analysis.)

Fig. 1-2: The number of farms (left axis) in the Great Plains has been decreasing over the last 70 years, however, the area in farms (right axis) has remained relatively steady during the same period. (Source: University of Texas Population Research Center 1998)

Fig. 1-3: Average historical ( ) precipitation and temperature in the Great Plains region.

Fig. 1-4: In the last 70 years, the rural population in the Great Plains has declined, while the urban population in the region has climbed steadily.

Fig. 1-5: The population in the Great Plains is aging. The number of people who are living in the region who are 65 years old or older has steadily increased over the last 70 years. Likewise, the total population of the region has been increasing, although this growth is most often felt in urban areas, with other areas of the region often losing population. There was a decline between 1980 and 1990 of the number of residents aged

Fig. 1-6: The services industry made up the largest piece of the Great Plains Gross Regional Product in Agriculture, forestry, and fisheries contribute the smallest piece, only about 2%. (Source: U.S. Bureau of Economic Analysis 1998)

Fig. 1-7: Although agriculture controls about 70% of the land area in all three sub-regions of the Great Plains (Northern Great Plains = Montana, North Dakota, South Dakota; Central Great Plains = Wyoming, Nebraska, Colorado, Kansas; Southern Great Plains = Oklahoma, New Mexico, and Texas), the contribution of agriculture to the Gross Regional Product in very small. Agriculture is very important in the region for many reasons, but it is not a major player in the regional economy compared to other industries. (Source: U.S. Bureau of Economic Analysis 1998, USDA 1997 Census of Agriculture)

Fig. 1-8: Rangelands and pastures cover over 50% of the land area in the Great Plains, and croplands (both dryland and irrigated) cover another 25% of the land area. (Source: Loveland 1991)

Fig. 1-9: Historical population trends and projections of population to 2050 in the Great Plains. All three scenarios project a population increase in the region in the future.

Fig. 1-10: Minimum (panels a-h) and maximum temperatures (panels i-p) over the Great Plains as projected by both model experiments at 2030 (average of ) and 2090 (average of ). Both the actual values (panels a-b, e-f, i-j, and m-n) and the deviations from the historical period ( ) (panels c-d, g-h, k- l, and o-p) are shown. The projected increases in minimum temperatures are greater than the increases in maximum temperatures. The CCC model produces hotter results in both time periods

Fig. 1-11: Precipitation over the Great Plains as projected by both model experiments at 2030 (average of ) and 2090 (average of ). Both the actual values (panels a-b and e-f) and the deviations from the historical period ( ) (panels c-d and g-h) are shown. The CCC model shows decreases in precipitation over parts of Oklahoma and Texas in both time periods, whereas, the Hadley model shows mainly slight to moderate increases in precipitation over the region.

Fig. 2-1: Atmospheric CO 2 levels have varied with the temperature over the last 150 thousand years. The rate of CO 2 increase in the last 200 years is unprecedented in the paleo-record.

Fig. 2-2: Two hundred years of Great Plains maximum temperatures are shown here. The first 100 years represent historical data, and the last 100 years shows results from the two climate model experiments. There is a trend towards increasing maximum temperatures into the future. (Source: Kittel et al. 1997, Kittel et al. 2000)

Fig. 2-3: Two hundred years of Great Plains minimum temperatures are shown here. The first 100 years represent historical data, and the last 100 years shows results from the two climate model experiments. There is a trend towards increasing minimum temperatures into the future. (Source: Kittel et al. 1997, Kittel et al. 2000)

Fig. 3-1: The CCC model experiment projects the possibility of severe droughts in the Great Plains at the end of this century. The Hadley model projects much less severe drought potentials.

Fig. 3-2: Historical trends ( ) and projections of trends into the future ( ) in actual evapotranspiration (AET), net primary productivity (NPP), minimum temperatures, maximum temperatures, and precipitation in cool-season (C 3 ) grassland regions of the Great Plains. (Source: Kittel et al. 1997, Kittel et al. 2000)

Fig. 3-3: Historical trends ( ) and projections of trends into the future ( ) in actual evapotranspiration (AET), net primary productivity (NPP), minimum temperatures, maximum temperatures, and precipitation in warm-season (C 4 ) grassland regions of the Great Plains. (Source: Kittel et al. 1997, Kittel et al. 2000)

Fig. 3-4: Historical trends ( ) and projections of trends into the future ( ) in actual evapotranspiration (AET), net primary productivity (NPP), minimum temperatures, maximum temperatures, and precipitation in wheat regions of the Great Plains. (Source: Kittel et al. 1997, Kittel et al. 2000)

Fig. 3-5: Average historical net primary productivity ( ) and model projections of average changes in NPP in the future ( and ). At 2030, the CCC model shows the largest decreases in NPP over parts of Oklahoma and northern Texas (panel b). This corresponds to the increase in temperature and the decrease in precipitation projected in this region. At 2090, besides a slight decrease in NPP over the panhandles of Texas and Oklahoma, both models project moderate increases in NPP over the region (panels e and f).

Fig. 3-6: Average historical soil carbon ( ) and model projections of average changes in soil carbon in the future ( and ). Over most of the region, in both time periods and for both model experiments, the soil carbon remains relatively stable into the future (panels b-c and e-f).