Over
the last few decades, average temperatures have risen throughout the
Great Plains, with the largest increases occurring in the winter months
and over the northern states. Relatively cold days are becoming less
frequent and relatively hot days more frequent.
In the future, temperatures are projected to
continue to increase with larger changes under scenarios of higher
heat-trapping emissions as compared to lower. Summer increases are
projected to be larger than those in winter in the southern and central
Great Plains. Precipitation is also expected to change, particularly in
winter and spring. Conditions are expected to become wetter in the
north and drier in the south. Projected changes include more frequent
extreme events such as heat waves, droughts, and heavy rainfall.
A note on the emissions scenarios
None of the emissions scenarios used in this report assume any policies
specifically designed to address climate change. All, including the
lower emissions scenario, assume increases in heat-trapping gas
emissions for at least the next few decades, though at different rates.
Projected
increases in temperature, evaporation, and drought frequency add to
concerns about the region’s declining water resources.
Most
of the region’s water comes from the High Plains aquifer (also referred
to by the name of its largest formation, the Ogallala aquifer) from
which water withdrawals already outpace recharge. Rising temperatures,
faster evaporation rates, and more sustained drought brought on by
climate change will add more stress to overtaxed water resources.
Agriculture,
ranching, and natural lands, already under pressure due to an
increasingly limited water supply, are very likely to also be stressed
by rising temperatures.
Agriculture
covers 70 percent of the Great Plains. As temperatures continue to rise, the
optimal zones for growing certain crops will shift. Pests will spread
northward and milder winters and earlier springs will encourage greater
numbers and earlier emergence of insects. Projected increases in
precipitation are unlikely to be sufficient to offset decreasing soil
moisture and water availability due to rising temperatures and aquifer
depletion.
Climate
change is likely to affect native plant and animal species by altering
key habitats such as the wetland ecosystems known as prairie potholes
or playa lakes.
Climate
change is likely to combine with other human-induced stresses to
further increase the vulnerability of ecosystems to pests, invasive
species, and loss of native species. Breeding patterns, water and food
supply, and habitat availability will all be affected by climate
change. Grassland and plains birds, already stressed by habitat
fragmentation, could experience significant shifts and reductions in
their ranges.
Ongoing
shifts in the region’s population from rural areas to urban centers
will interact with a changing climate, resulting in a variety of
consequences.
As
young adults move out of small, rural communities, the towns are
increasingly populated by a vulnerable demographic of the very old and
the very young, placing them more at risk for health issues that are
projected to increase with climate change. The region is also home to
65 Native American tribes; the people on tribal lands have limited
capacities to respond to climate change. Many reservations already face
severe problems with water quality and quantity and these problems are
likely to be exacerbated by climate change.
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