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Hurricane Ida struck the coast of Louisiana at a wind speed of 150 miles per hour on August 29, 2021, the day after Hurricane Katrina destroyed New Orleans on almost the same path.
Ada is one of themStrongestTropical storms have been recorded in the state.Its storm surge is smaller than that of Hurricane Katrina, but it is very fastFlooded streets and housesOutside the dike system, many residents are subject to mandatory evacuation orders.Most of New OrleansRebuild the embankmentIt seems to have been maintained, but the strong wind tore the roof, knocked down the trees and caused “Catastrophic damage“To the transmission line, cut off the electricity in the entire area.
The four articles in our archive, written by meteorologists and atmospheric scientists, provide some insights into why the New Orleans region is at high risk of severe hurricanes and how climate change relates to these powerful storms.
1. Some areas are more vulnerable to hurricane damage
New Orleans is one of the places with the highest risk of hurricanes along the coast of the United States. An analysis by the US National Oceanic and Atmospheric Administration estimates that hurricanes may occur within approximately 50 nautical miles in the area.Once every seven yearsThere is a major hurricane every 20 years.
Few characteristicsCan expose an area to a higher risk of destructive hurricanesAthena Masson, a meteorologist at the University of Florida, explained.
She wrote that one factor is timing. Storms tend to hit Texas and the Atlantic coast earlier in the season, while the northern Gulf Coast faces a higher risk from late August to October. In late autumn, trade winds tend to push the storm away from the western bay area.
The other is the shape of the seabed. A shallow continental shelf like Louisiana can generate powerful storm surges.Part of the coast is submergedMore than 9 feet of waterWhen Idada.
Mason said that the conditions along the storm’s path, especially the water temperature, determine to a large extent whether a tropical storm will become a dangerous hurricane.
“The formation of a hurricane requires three key factors: warm sea water is at least about80 degrees Fahrenheit(26.5 C), a thick layer of moisture extends from the sea to approximately 20,000 feet, with the smallest verticalWind shearTherefore, thunderstorms can grow vertically without interruption,” Mason wrote.
Hurricane Ida has all three at the same time. When Ida crossed, the surface of the Gulf of Mexico was unusually warm,Temperature is approximately 85 to 90 F(29.4 to 32.2 degrees Celsius). The storm also has plenty of moisture and little wind shear to stop it.
2. What is the relationship between climate change and hurricanes?
The 2020 hurricane season broke records, with 30 named storms, 7 major hurricanes of category 3 or higher intensity, and 10 storms that experienced rapid intensificationLike IdaBefore landing.
When analyzing the 2020 season, atmospheric scientist James Ruppert of Pennsylvania State University and Allison Wing of Florida State University discussedThe role of climate change in increasing hurricane risk.
Regarding the question of whether climate change affects the number of hurricanes, there areNo detectable global trendIn hurricane frequency, research using computer models hasConflicting results, Ruppert and Wing wrote.But they said that there is aTend to a stronger storm– Hurricane of category 3 and higher, such as Hurricane Ida.
“Because the ocean temperature controlsPotential strengthTropical cyclones, climate changeVery likely to fall behindThis trend is expectedcontinue,” they said. “The United States also seesMore storms and extreme rainfall. As the temperature rises, more water can evaporate into the atmosphere, resulting inThere is more moisture in the air. “
3. Climate change and storm surge
Climate change also affects the extent of hurricane damage in another way: it gradually increases the risk of storm surges.
Storm surges—the massive amounts of water that hurricanes push along the coast—are one of the greatest threats to life and property from any hurricane.The height and extent of the storm surgeDepends on the intensity and scale of the hurricane, butSea-level riseAnthony Didlake Jr., a meteorologist at Pennsylvania State University, explained that the baseline height of the ocean is being raised.
“As the water warms,It expands, In the past century, sea levels have risen slowly because ofGlobal temperature riseThe fresh water produced by melting ice caps and glaciers has also exacerbated sea level rise.They are togetherIncrease the height of the background ocean“When a hurricane arrives, the higher ocean means that the storm surge can bring the water farther inland, causing more dangerous and wider impacts.” “
4. IPCC on Hurricanes
thisThe latest global climate analysisThe United Nations Intergovernmental Panel on Climate Change provided similar conclusions.
It discusses evidence that hurricanes are now stronger, faster, and slower than they were 40 years ago, leading to more rainfall. The impact of greenhouse gas emissions on these changes is still being determined; Robert Cope, author of the report’s chapter on ocean and sea level rise, said the reduction in particulate pollution has also had an important impact.
Kopp explained: “The most obvious effect of global warming is that a warmer atmosphere contains more moisture, leading to more extreme rainfall, as seen during Hurricane Harvey in 2017.” “Looking ahead, we Rainfall from hurricanes and hurricanes is expected to continue to increase.”