Summary

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Louisiana’s diverse transportation network is vital to the state’s economy. This network connects communities, traverses complex coastal topography, and supports key industries, including energy, freight, and tourism. Louisiana is a hub for the petrochemical industry, and is home to one of the largest ports in North America. Each year, transportation professionals in Louisiana must deal with impacts of climate and weather extremes. Some of the state’s most frequent and damaging hazards include flooding, subsidence and sea level rise, severe thunderstorms, heat and humidity, ice storms in the north, and tropical storms. These weather conditions degrade and damage the state’s transportation infrastructure assets, delay or disrupt movement, and pose safety risks to the millions of people who rely on the network.

 

While Louisianans are used to extreme weather, changes in weather patterns and climate conditions are being observed. Projections indicate that future conditions may be outside of the range that the state has been accustomed to. If these changes are not accounted for, physical infrastructure may not be prepared to withstand future extreme events, leading to higher maintenance costs and reduced lifetimes. In addition, as the population of the state grows, and more and more use the network, infrastructure reliability will become even more vital. Facing these challenges requires planning for the future. By incorporating future projections of weather and climate into planning and design, transportation professionals can prepare the network for a suite of possible hazards. Because transportation investments are often intended to last for decades, many professionals consider these projections critical for designing resilient, cost-effective infrastructure.

 

We used a broad suite of reliable climate data products to project trends in temperature and precipitation extremes of relevance to the transportation sector through the 21st century.

 

Based on our findings, Louisiana is likely to experience:

• An increase in heat and flood hazards, while winter weather, already rare in the south, will become rarer still: Assuming a high degree of climate change, Freeze-thaw cycles in the state decrease 60-80% by the late 21st century. Winter weather, such as snow and ice, decreases 60-90% by the same period, although the average intensity of a given winter weather event may not change. Hot days (≥95oF) show a marked increase, and could triple in frequency across much of the state by 2050, and increase by a factor of 4-6 by the late 21st century. Heavy precipitation and drought both increase in frequency, suggesting that Louisiana’s future climate is marked by high precipitation variability. The historical 100-year rainfall in Southeast Louisiana, which is already vulnerable to flooding, could be the future 30-40-year rainfall by 2050, or 25-35-year rainfall by 2090.

• Sea level rise will likely shift the geography of the coastline: Since the early 20th century Louisiana has lost almost 2,000 square miles of land to the ocean through sea-level rise and subsidence. With sea levels projected to rise anywhere between 1-4 feet by the end of the 21st century, coastal transportation and energy infrastructure is at high risk, and could result in billions of dollars of losses though storm surge and inundation, and costs to relocate or replace coastal infrastructure.

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