Extreme weather events include severe winter snow storms, ice storms, high winds, hail, tornadoes, lightning, drought, intense heavy rain, floods, heat waves, extreme cold snaps, and unexpected frosts. Natural systems are generally adapted to this variability (although recovery from some types of events can be quite long); however, climate extremes can have significant economic effects on the cities and communities in the Great Plains. In addition, the extremes of hot and cold, as well as wet and dry, can pose challenges for livestock and agricultural enterprises as well.

Analysis of the historical record (1895-1995) indicates an increasing trend in high intensity rainfall events (greater than 2 inches/day) in the southern Great Plains. Model results suggest that the frequency of high intensity rainfall will continue to increase in the southern Great Plains, resulting in more rainfall in shorter periods of time. The historical record also indicates that extreme precipitation totals are increasing in the Great Plains. In models, the frequency of very high temperatures and heat stress events support that the frequency and intensity of such events are likely to increase.

Because it is difficult to separate environmental, social, and economic impacts from extreme events, they will be discussed together. Potential adaptation options follow.

 

Heat stress events can be triggered for livestock and for humans when the temperature exceeds 90°F (32°C) for three or more consecutive days. The number of times that a climate division in each of the 8 Great Plains states experiences three consecutive days where temperatures exceed 90°F (32°C) increases in both scenarios. The 95% confidence interval for the historic period of 1960 to 1990 is shown as two dashed lines. Sources: VEMAP data, Natural Resource Ecology Lab, Colorado State University.

Environmental, Social and Economic Impacts

Stakeholders in the region view slow changes in climate averages as less of an issue than the possibility of more intense or more frequent extremes. Hail suppression programs, rainfall enhancement programs, and drought mitigation programs are currently operating in different areas in the Plains. Current concerns and impacts related to extreme events are highlighted below as examples of potential impacts should a changing climate in the Great Plains increase occurrence of extreme events.

In May of 1999, an outbreak of F4-F5 tornadoes hit the states of Oklahoma, Texas, Kansas, and Tennessee, resulting in at least $1 billion in damages and 54 deaths. In the fall of 1998, severe flooding in southeastern Texas from two heavy rain events with 10-20 inch rainfall totals caused approximately $1 billion in damages and 31 deaths. The severe drought from fall 1995 through summer 1996 in the agricultural regions of the southern Great Plains resulted in about $5 billion in damages.

Urban and industrial infrastructures have also been affected by extreme weather events. For example, the summer 1998 heat wave and drought severely affected roads and pipelines in Texas. In addition, this extreme event resulted in over $6 billion in damages from Texas/Oklahoma eastward to the Carolinas and at least 200 deaths. The April 1997 flood put nearly 90% of Grand Forks, North Dakota under water and caused over $1 billion in damages.

In the winter of 1996-97, eight blizzards in North Dakota resulted in the deaths of over 120,000 cattle, 9,500 sheep, and several thousand hogs and poultry with direct losses of $250 million. Heat, particularly hot-humid conditions, affects intensive livestock operations more than cold, and cattle are affected to a greater degree than sheep. In August 1992, a 3-day heat wave after a relatively cool period in central and eastern Nebraska caused several hundred feedlot cattle deaths. In a July 1995 heat wave, over 4,000 feedlot cattle died in the central US. Weather is the primary factor in the timing of calving seasons because newborns and neonatal animals are vulnerable to extremes of both heat and cold.

Any or all of the above examples could become more regular occurrences should climate changes increase the frequency of extreme events. Each of these events can cause economic as well as physical and emotional difficulty for those who experience them.

Climate in the Great Plains is inherently variable and decisions regarding land use, land management, and development are generally made with this variability in mind. This variability underscores the need for adaptation strategies that reduce risk and uncertainty because physically, emotionally, and psychologically, people cope better with a disaster or an abrupt change if they are prepared or if a response plan is in place. Some of the options for being better prepared could include:

• Provide more timely, accurate, and easily accessible information about near-term weather (weeks to growing season), extreme weather events, and forecasts for weather 6 to 18 months in the future;
• Develop strategic (long-term) plans that include a tactical (short-term) response that can be initiated when needed. For example, the stress of a heat event can be minimized if livestock operators have 3-4 days to reduce feed intake (and therefore, metabolic heat production) in cattle;
• Create learning communities in which stakeholders share information with each other about how to enhance resilience to variability and change. Information outreach could include short television segments containing information pieces on climate and other aspects of the environment, a web site with interactive information, newsletters, and partnerships with, for example, the National Park Service to develop information kiosks about environmental changes; and
• Develop drought management plans that are mitigative in addition to being reactive and that reflect the changing demographic and economic conditions within Great Plains states.