The Fifth National Climate Assessment, released earlier this month, warns of widespread climate impacts across the United States. The effects on people and the environment in the Mississippi River basin are extreme, but experts stress that it is not too late to slow the worsening effects.
From its source in Minnesota to its salty mouth in the Gulf of Mexico, the Mississippi River spans two regions of the country. Midwest and Southeast. The entire basin, including the river's many tributaries, spans five regions. The past two summers have brought extreme drought – threatening crops and shipping. excessive heat? and isolated extreme rainfall and flooding. The national report finds that this will become common in the future.
The report is clear in its indictment of human activity as the cause of the increase in average global temperature. In the contiguous US, temperatures have risen 2.5°F since 1970, compared to a global average rise of about 1.7°F over the same period.
While this increase in temperature can be attributed to its release greenhouse gases around the world, the report highlights a range of human activities that drive the economy throughout the Mississippi River Basin, including agriculture and shipping.
But there's still opportunity for Mississippi industries to adapt to protect the nation's largest watershed.
Agriculture and other impacts on the Midwest
The report attributes climate change to human activities. The increased concentration of greenhouse gases in the atmosphere comes mainly from the burning of fossil fuels, but deforestation and agricultural practices also contribute.
These gases have led not only to increased temperatures, but also to more frequent and severe extreme weather events. In the Midwest, extreme weather changes are wreaking havoc on crops and communities alike.
The impacts on agriculture and food production are “(some) of the most visible and worrisome aspects of climate change,” said John Baker, chief scientist at the U.S. Department of Agriculture, during a briefing on the report.
The Midwest is one of the most intensively agricultural regions in the world. Although average corn and soybean yields have increased in recent decades, these gains will not last. The report predicts that extreme fluctuations in rainfall will reduce future crop yields as well as livestock production.
Precipitation patterns are changing in the Midwest, with winter and spring precipitation expected to increase, while summer and fall precipitation expected to be more variable. Those changes are already visible in agriculture, with earlier snowmelts causing wetter springs that delayed corn planting by up to a month in some places.
Episodic droughts have also reduced crop yields, despite increasing annual rainfall. A lack of rain brought drought to the Mississippi River basin this summer, and the the drought is expected to persist into the winteraccording to the US Army Corps of Engineers.
Once the drought passes, river flooding is expected to increase in the Ohio, upper Mississippi and parts of the Missouri River. This flood of high water content and longer duration is also expected to adversely affect the Floodplain forests of the Mississippi River basin by soaking the trees longer than they can bear.
Periods of high rainfall also cause damage through fertilizer runoff from farmland into the Mississippi River. The runoff has increased in recent decades and is expected to continue to increase, eventually ending up in the Gulf of Mexico where it creates a huge “Dead Zone.” These years it was almost as big as Yellowstone National Park.
Shipping and implications in the Southeast
In the lower Mississippi, where nitrogen runoff from the upper basin meets salty water from the Gulf of Mexico, extreme drought dominated the headlines for the past two years. The flow of the mighty Mississippi was not enough to prevent saltwater from entering the river, threatening drinking water. As of Nov. 20, the saltwater wedge is holding a steady 63.2 river miles in Louisiana.
Sea level rise increases the risk of saltwater intrusion. The report predicts that over the next 30 years, coastal sea levels along the contiguous U.S. will rise about 11 inches, roughly equivalent to the observed rise over the past 100 years. On the Gulf Coast, land loss to the sea has been accelerated by the withdrawal of groundwater and fossil fuels.
The shipping industry is already feeling the effects of climate change and is looking for ways to adapt to these increasingly chronic problems. This year's low water conditions have come at an inopportune time for the basin's economy: harvest season.
The drought has led to a serious disruption to barge transport which causes economic hardship to farmers. The shift in that river supply chain is slowing both the import and export of goods at an important gateway for the country, a disruption the report predicts could lead to job losses if it becomes routine.
This summer's drought coincided with the hottest year ever recorded on Earth. New Orleans tied with two Indonesian cities for the the second-longest heat streak, counting in 17 consecutive days. The wetlands around New Orleans became so dry that a swamp fire it burned for more than a month.
The current drought should not obscure the possibility of floods to come. The report describes an increase in the severity and frequency of extreme weather events. For the Mississippi River Basin, Jill Trepanier, an associate professor at Louisiana State University who studies weather and climate, is more concerned about the extreme variability of rainfall.
“One year can be very different from the next,” Trepanier said. “That's part of the expectation now, these really big differences.”
Extreme opportunities
Many climate researchers who were not involved in drafting the federal report were pleased to see it emphasize climate justice. Extreme heat, drought, flooding, wildfire smoke, and vector-borne diseases will not affect all residents equally. As defined in the report, climate justice is the recognition of diverse values and past harms, the equitable distribution of benefits and risks, and the procedural inclusion of affected communities in decision-making processes. This includes many of the communities at the forefront of the changing Mississippi River watershed.
“We are not all experiencing the effects of climate change in the same way. Communities of color, low-income communities, and indigenous peoples are some of the most disproportionately affected by climate change and extreme events,” said Deepti Singh, author of the report's chapter on Climate Trends.
The report points out that there needs to be a focus on the knowledge of indigenous peoples and the importance that self-determination can have on their resilience to climate change. One example focuses on how heating and water distribution endangers wild rice, a culturally important crop for Midwest tribes.
A chapter on Tribes and indigenous peoples highlights a research project undertaken by the College of Menominee Nation in Keshena, Wisconsin to help the community understand how climate change affects plants on the Menominee Indian Reservation, the largest reservation east of the Mississippi River.
The Milwaukee Journal Sentinel has reported how Knowing about Great Lakes tribes could be the key to navigating climate change in the Midwest. This year, wild rice crops were decimated by a fungus that causes brown spot disease, which researchers believe is spreading rapidly since wetter weather brought on by climate change.
The report acknowledges that rising temperatures, rising sea levels, and changing precipitation patterns are also causing extreme weather events, such as more intense Gulf Coast hurricanes.
Other disasters may be more surprising, such as an increased chance of tornadoes hitting the lower Mississippi River basin. Tornado Alley, usually thought to be centered over the Great Plains, is shifting eastward. Tornadoes also become more frequent during the fall and more intense.
“It's called extreme climate change because it's not completely one way or the other,” said Rebecca Malpass, director of policy and research at The Water Collaborative in New Orleans. Both droughts and floods will become more intense. “We will continue to oscillate between these two extremes more often as the decades go by.”
Adaptation — such as improving flood management, building energy microgrids and testing early warning systems — are key to protecting millions of people, as well as the economy across the basin. While adaptation is occurring on a piecemeal basis, the report concludes that it is not happening fast enough to reduce even today's climate-related risks.
As the pace of climate change and extreme weather accelerates, adaptation will require more investment. The Biden administration has already made some historic investments, including Bipartisan Infrastructure Act and Justice40 initiativewhich dictates that 40% of federal climate investments go to disadvantaged communities.
This story is his product Mississippi River Basin Ag & Water Deskan independent reporting network based in University of Missouri in cooperation with Report on Americawith major funding from the Walton Family Foundation. Sign up to repost stories like this for free.
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