Drought on the Mississippi: Climate Change Hits the Marine Transportation System

During late Summer and early Fall of 2022, intense heat and drought significantly decreased the water level in the Mississippi River, reaching an unprecedented low point in October 2022. This led to barges becoming stranded in mud and sand, necessitating lighter barge loads, shorter barge trains and the implementation of one-way traffic in certain river sections. At this low water level of October 2022, approximately 2,000 barges were backed up along the river waiting passage. From October to November 2022, low water meant that a round trip on the Lower Mississippi from New Orleans to Cairo, IL, which normally takes 13 to 14 days, took almost 27 days.

This situation repeated when the river reached an even lower level in October 2023. The consequential disruption heavily impacted essential commodities transported by river barges, including northbound fertilizer shipments and southbound grain transports. Reduced availability of barges for fertilizer heading upriver meant fewer barges for grains traveling downstream, and vice versa. Consequently, barge rates soared by more than 400% above average. Barge labor productivity (the work or output achieved by a unit of labor within a specific timeframe) dropped significantly. Climate change has hit the marine transportation system!

The MCAT Project Takes a Look at Fertilizer

CCICADA was led to the study of the impact of low water on the Mississippi through discussion with the Maritime Administration (MARAD), the US Army Corps of Engineers (USACE), the U.S. Committee on the Marine Transportation System (CMTS) and the ESF-1 Working Group of the FEMA Region X Regional Interagency Steering Committee. These discussions were part of CCICADA’s project “Modeling the Impact of Complex Multi-vector Disruptions to the Marine Transportation System (MCAT).” In the MCAT project, CCICADA, in collaboration with two other DHS Centers of Excellence, the CREATE Center led by USC and the CAOE Center led by Arizona State, is studying examples (scenarios) of multiple, overlapping disruptions, identifying their potential economic impact (both direct and indirect), and identifying and evaluating potential countermeasures. While the Marine Transportation System is resilient to many kinds of disruptions occurring one at a time, little is known about the impacts of complex, multi-vector disruptions, which can be greater than the sum of the impacts of the individual disruptions. Modeling multiple vector disruptions and identifying potential countermeasures can help policy makers, business leaders, and others anticipate, plan for, mitigate, and recover from them.

With input from MARAD, USACE, and CMTS, as well as American Waterways Operators (the tugboat, towboat and barge industry’s advocate) the MCAT team produced a scenario with low water on the Mississippi as a central disruption and its impact on the fertilizer market as the main emphasis. CCICADA researchers had to become familiar with the transportation, use, and economics of fertilizers.

Barge tow. Credit: Wikimedia commons, William Alden III, no changes

Shipping Fertilizer on the Mississippi

Shipping U.S.-produced or imported fertilizer by river is a critical way to get it to market.  Transportation by barge is cost-effective for high-volume bulk commodities such as fertilizer and grain. A typical inland barge has a capacity 15 times greater than one rail car and 60 times greater than one semitrailer-truck. A tow of 15 barges can move more than 22,000 tons of fertilizer using 44 gallons of fuel per mile (on a tugboat). In contrast, it would take about 800 gallons to move that much fertilizer a mile by truck. A 15-barge tow, pushed by a single towboat, can carry as much cargo as 870 large trucks, or over 200 rail cars.

Damage to Lock 27

The Mississippi River hosts a critical yet aging system of locks, some dating back to the 1930s, susceptible to occasional damage. Major damage to a lock can take several months to repair and can significantly slow barge transportation. If major lock damage were to occur at the same time as a low water disruption on the river, the economic impact could be much worse in the context of such a “complex disruption.”

Lock 27. Credit: US Army Corps of Engineers

The second component of the Mississippi River scenario developed in the MCAT project is the failure of a key lock near St. Louis. Locks can be damaged by failure of equipment, vessel accidents, or natural causes such as earthquakes. For example, in 2013, when river flow was high, a towboat tore loose, breaking wires holding barges together and breaking gates to a lock: it took two weeks to make repairs. In its study, the MCAT team used Lock and Dam 27 at Granite City, Illinois for failure – a large portion of fertilizer and grain loads use this lock.

Most locks have a primary chamber that is 1,200 feet in length and 110 feet in width, which allows for 15 barges to be grouped in a 3 by 5 arrangement.  Some locks have a second, parallel chamber of the same size, but others have a secondary chamber that is only 600 feet long, or no secondary chamber at all. To use a smaller, secondary chamber (for example, when the primary chamber is undergoing maintenance), mariners must break up the standard 15 barge configuration into two smaller groups, push them through the locks in sequence, and then reassemble them. At a minimum this triples the amount of time this operation takes, since the chamber must be either raised or lowered (depending on the direction of travel), before the second group can proceed. If other barges are waiting their turn the delay can quickly multiply.  Breaking up and reassembling the barge configuration (or “the tow”, as it is called) also takes time and creates added risk of injury as crew members handle lines while the heavy barges are moving about.

Disruption to the Port of New Orleans

Port of New Orleans after Katrina
Photo credit: Fred Roberts

The relatively small amount of imported nitrogen fertilizer (about 10% of U.S. consumption) typically arrives by vessel at or near the port of New Orleans where it is then transported to market by barge, rail, or truck.

The third component of the complex scenario is a disruption of fertilizer imports to the US coming through the Port of New Orleans. Fertilizer imports through this Port could be affected by a hurricane, damage to port infrastructure, labor strike, heat event, cyber-attack, or a host of other possible disruptions. All causes of the disruption at the Port of New Orleans could lead to the same daily import reduction, though they would likely differ in terms of its duration.

Economic Impact of the Disruptions

The MCAT team, led by Professor Adam Rose of the CREATE Center, has been developing a user-friendly, decision-support tool for use by the Coast Guard and others to improve risk management. This MCAT Tool aims to identify direct and indirect economic impacts of disruptive events. It uses a computable general equilibrium (CGE) model consisting of over 100 countries with 65 sectors each and determines economic impacts of complex disruptions and provide insight into how to minimize them.

The MCAT analysis estimated changes in barge transportation rates and barge labor productivity rates as a function of water level. The researchers then estimated the effect on barge transportation rates and barge labor productivity rates of the lock failure, as a function of length of time of outage. And they studied the effect of different assumptions about percentage of import reduction in New Orleans.

The MCAT tool allowed us to calculate the overall negative impact on US GDP and the overall negative impact on individual states, the effect on the unemployment rate, and the effect on the rate of inflation.

Testimony to the Senate Budget Committee

Professor Rose was invited to testify before the Senate Budget Committee in October 2023 on the Economic Impacts of Climate Change on Supply Chains. His testimony was built around our Mississippi River low water scenario and economic analysis and was well received.

Drought Affecting the Panama Canal

Panama Canal. Credit: Stan Shebs no changes

Climate change is affecting other important bodies of water. Starting in May of 2023, the Panama Canal was at or below record low levels, as a result of drought in Panama. This has had dramatic impact on Canal capacity and has led to major disruptions to shipping world-wide.

The low water reduced ships going through the Canal from 38 to 18 per day. Shippers seeking priority to get ahead of the queue paid millions. Major shippers like Maersk are using a land bridge across Panama, or air cargo, to avoid delays. The CCICADA-CREATE team plans a major research study on the impact of low water on the Panama Canal. This is only part of a major initiative on the many impacts of climate change on the marine transportation system in particular and the supply chain in general.


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