New Orleans was already an “island of heat.” Then Ida turned off the power


Sunday a hurricane Ida reached a collision in Louisiana, colliding with Hurricane Laura in 2020 as the strongest storm to ever hit the state. Winds of up to 150 miles per hour have torn the electrical infrastructure, leaving a million people without electricity. All eight power lines to New Orleans have been cut off.

Now the temperature in the 90s, and harsh humidity – still summer – plunges Louisiana into a multi-layered crisis: without electricity, residents who do not have a generator, also lack fans or air conditioners. Utilities Entergy says the power supply cannot be restored for three weeks, but local officials warn that for some it could be a month. “I’m not happy for 30 days, the people of Entergy are not happy for 30 days,” Louisiana Gov. John Bell Edwards told a news conference on Tuesday. “No one who needs power is happy with that.”

The disaster is particularly acute in New Orleans and other cities that already form “islands of heat” in the landscape. These are places without enough trees or other greenery where the built environment absorbs the sun’s energy during the day, slowly releasing it at night. Urban temperatures can be 20 degrees Fahrenheit hotter than surrounding rural areas. And here’s the extremely bad news: an analysis published in July by research group Climate Central found that the effect of the thermal island of New Orleans is worse than in any other U.S. city.

If you’re wondering what the hell of a climate crisis looks like, that’s all. “The whole region is already hot and humid over the summer,” says Louisiana State University climatologist Barry Keim, who is also a state climatologist. “And you throw on the hot hot islands an impact that only exacerbates it, and you knock out the air conditioning system. This is a recipe for disaster. “

Several factors are turning cities into heat islands. Concrete, asphalt and brick absorb heat very well. When the surrounding air cools at night, these dense materials can emit only part of that heat, so they can be even warmer when the sun rises the next day and give off more energy. “So you get this kind of accumulation factor over a few days of heat,” says Portland State University climate adaptation scientist Vivek Shandas, who studied the island’s heat effect. Portland, New Orleans and dozens of other cities. After Hurricane Ida, he said, it now looks like New Orleans is facing a “series of days of excessive heat.”

The structure of the constructed environment is also an important factor. Tall buildings absorb sunlight and block wind, trapping heat in central areas of the city. And the buildings themselves produce heat – especially factories – or emit hot air from AC units.

Compare this to a countryside full of trees: When the sun knocks down a forest or meadow, the vegetation absorbs that energy, but in turn emits water vapor. In a sense, the green zone “sweats” to cool the air, making the temperature much more tolerable.

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In an ideal world every city would be full of trees to cool it. But in a metropolis like New Orleans, Shandas says, temperatures can vary greatly, even block by block. Brick buildings retain heat better than wooden ones, and greasy highways are heated by sunlight. But if the buildings are interspersed with trees, and if you have a lot of greenery, such as parks, all this greenery helps to cool the air.

On an August day last year, Shandas and other researchers made 75,000 temperature measurements from across New Orleans. They found that the coolest areas were located at about 88 degrees, and the hottest areas soared to 102 degrees. “It’s related to greenery, it also has a lot to do with the configuration of buildings as well as building materials,” Shandas says.


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