NCA by Region: Midwest & Southwest

This post is the third part of our series summarizing the recently released National Climate Assessment (NCA), a detailed report published by the White House in early May. The report, which is legally mandated to be released every four years, is an evaluation of the United States’ vulnerability to climate change and the impacts that can be expected in each region from a warming climate. Building off of our summary of the NCA and the impacts expected on the East Coast, this post focuses on the climate change impacts expected in the Midwest, Great Plains and Southwest regions.



Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, and Wisconsin

The Midwest hosts 20% of the US population and produces a regional GDP of $2.6 trillion (19% of the entire US GDP). Expansive agricultural lands, forests, the Great Lakes and important urban and industrial areas join together to make up this ecologically diverse region. In general, climate change will likely amplify the impacts that the region is already beginning to feel, including extreme heat, heavy downpours, flooding and shifting ecosystems.

  • Risks to agriculture: While longer growing seasons and increased carbon dioxide in the atmosphere may improve the outlook for some crops, these benefits will be progressively offset by threats from droughts and extreme weather events. Both heat stresses and more unexpected late spring freezes are likely to damage crops early in the season. Changes in prevalence of pests, diseases and opportunistic native and non-native species will also expose crops to threats that they are unable to adapt to.
  • Shifting ecosystems: Rising temperatures are already causing many habitats and tree species to move northward in the Midwest. These changes in forest composition will reduce the effectiveness of the regions’ forests to trap carbon dioxide and mitigate further climate change. Biodiversity lost in the forests can also be expected as the species cannot migrate as fast as the ecosystems are changing.
  • Risks to the Great Lakes: The Great Lakes are the nation’s largest freshwater feature, and are already showing higher temperatures and lower amounts of winter ice than historical averages. Ice cover has fallen by 24% since the 1970s in the Great Lakes. While this increases opportunities for lake transport, this in itself has threats of shore scouring and the introduction of more invasive species.


Great Plains

Kansas, Montana, Nebraska, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming

The Great Plains region is specifically vulnerable to climate change because the communities are already deeply tied to the climate, and in much of the region, too little rain falls naturally to replace that needed by plants, animals and humans. While the people of the Great Plains have historically been incredibly adaptable to challenging changes in the climate, climate change will increase the difficulties that they face daily.

  • Extreme heat in southern areas: High temperatures (days over 100 ° F in the Southern Plains and 95° F in the Northern Plains) will increase in frequency with climate change, with days over 100° F projected to double in the Northern Plains and quadruple in the Southern Plains by mid-century.
  • Increased demand for water and energy: Rising temperatures will heighten demand for both water and electricity to maintain livable situations in much of the Great Plains. While there will be a growing likelihood of heavy rain and floods, they will be more than offset by a higher likelihood of severe droughts. Marginal land will likely become deserts, and legal and political competition for water sources will become increasingly heated.
  • Positive and negative impacts for agriculture: While warmer temperatures means longer growing seasons in much of the Plains and increased winter precipitation could increase soil fertility, more extreme rainfall could create soil that is too wet to plant in the spring. Additionally, with warmer winters, some pest species may be able to survive the winters and wreak havoc on young plants in the spring. High temperatures will also threaten livestock and cause a northward shift of ranching practices.



Arizona, California, Colorado, Nevada, New Mexico, and Utah

As the hottest and driest region in the US, the Southwest is the most vulnerable to decreases in precipitation and increases in wildfires, both of which are already devastating this region of the country. With a population that is expected to increase 68% by 2050, the stresses on this region’s water sources will only increase with warmer temperatures and urbanization. As a partial coastal region, residents along the coast will also have to face rising sea levels, flooding and extreme weather events. With ports that handle half of the country’s incoming shipping needs, these threats could significantly impact the US economy in the coming century.

  • Limited water sources impacts agriculture and urbanization: Severe and sustained droughts, made more frequent by rising temperatures and shifts in snowmelt, will stress water sources for both agriculture and sprawling urban areas, both of which are already over-utilized in many areas. Changes to the growing seasons of specialty foods could decrease crop yields for corn, tree fruit, and grapes while stressing livestock. These changes could cause a northward shift of agriculture, displacing entire communities.
  • Increased wildfire frequency and severity: While wildfires are an essential part of the Southwestern landscape, the Federal Government made the mistake in the early 20th century of implementing a policy to extinguish all fires. This allowed wood and other fuels to over-accumulate and encouraged urban areas to develop on the outskirts of fire-prone regions. Climate change will bring increased warming, insect infestations and increased dryness from droughts, drastically increasing fire vulnerability. Models predict a doubling of burned area in the southern Rockies and a 74% increase in burned area in California by 2100.
  • Coastal damage: In the past 100 years, sea level on the California coast has risen 6-8 inches. Flooding and erosion in coastal areas is already occurring at current sea levels in California during storms and extreme high tides, causing significant infrastructure damage. If adaptive measures are not taken, coastal highways, bridges, and other transportation infrastructure, as well as 420,000 coastal residents, will be at an increased risk of severe damages from flooding.


Stay tuned later this week for our final post in the series on the climate change impacts on the Northwest, Hawaii and Alaska.


Image Credit: NOAA via Wikimedia Commons


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