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 (1961-1990) 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 15-34.
Fig. 1-6: The services industry made up the largest piece of the Great Plains Gross Regional Product in 1996. 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 2025-2034) and 2090 (average of
2090-2099). Both the actual values (panels a-b,
e-f, i-j, and m-n) and the deviations from the
historical period (1961-1990) (panels c-d, g-h, kl, 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 2025-2034) and 2090 (average of
2090-2099). Both the actual values (panels a-b
and e-f) and the deviations from the historical
period (1961-1990) (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 CO2 levels have varied with the
temperature over the last 150 thousand years. The rate of
CO2 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 (1961-1993) and projections of trends
into the future (1994-2099) in actual evapotranspiration (AET), net
primary productivity (NPP), minimum temperatures, maximum
temperatures, and precipitation in cool-season (C3) grassland regions
of the Great Plains. (Source: Kittel et al. 1997, Kittel et al. 2000)
Fig. 3-3: Historical trends (1961-1993) and projections of trends into
the future (1994-2099) in actual evapotranspiration (AET), net
primary productivity (NPP), minimum temperatures, maximum
temperatures, and precipitation in warm-season (C4) grassland
regions of the Great Plains. (Source: Kittel et al. 1997, Kittel et al.
2000)
Fig. 3-4: Historical trends (1961-1993) and projections of trends into the
future (1994-2099) 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
(1961-1990) and model projections of average changes in
NPP in the future (2025-2034 and 2090-2099). 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 (19611990) and model projections of average changes in
soil carbon in the future (2025-2034 and 20902099). 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).