Climate change impacts already underway in the United States are projected to intensify, according to the Fourth National Climate Assessment published Friday.
Whether we avoid the most severe effects depends largely on what we do now to reduce greenhouse gas emissions and adapt to climate change, according to the report produced by the U.S. Global Change Research Program.
The program is required to study climate change impacts and major trends — including to agriculture, energy production, land and water use, transportation, human health and welfare, biological diversity and the environment — and report to Congress and the president at least once every four years. The Trump administration is undoing several environmental regulations designed to reduce carbon emissions from coal-fired power plants, cars, and oil and gas wells.
Compared with the rest of the United States, the Midwest is expected to see the largest increase in average annual temperature. The average annual five-day maximum temperature for northern Minnesota, currently about 88 degrees, is projected to rise to 95 degrees by 2065, depending on the scenario. Chicago, which rarely reaches 100 degrees, could average many as 60 such days every year by the end of the century.
Air quality — from increased concentrations of ground-level ozone to fine particle pollution and pollen — is projected to decline as a result of climate change and cause an additional 200 to 550 premature deaths in the Midwest each year by 2050.
Extreme temperatures combined with increased rainfall are also projected to reduce agricultural productivity in the Midwest, which churns out 18 percent of the country’s gross domestic product, to 1980s levels by mid-century. Corn yields are expected to decline for the entire region as temperatures rise, though soybean yields could increase in the upper Midwest.
Production of wild rice, grown by tribes and others in the wetlands of northern Minnesota, Wisconsin and Michigan, is expected to fall as extreme temperatures, climate-related disease and pest outbreaks shift hospitable growing regions farther north.
Meanwhile, increased rainfall from April to June is expected to reduce the spring planting window and increase soil erosion, while wetter conditions at the end of the growing season would promote the growth of mold and fungus.
Flooding on the Mississippi and the Missouri rivers, which flow through the Midwest and can overwhelm sewer system and drinking water sources, is projected to worsen. Infrastructure damage in the Midwest, which contains the most vulnerable bridges in the nation, is projected to rise from $3.3 billion in 2050 to $6 billion per year in 2090.
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