Most people assume that the biggest climate threat will be in the form of something new: hurricane force winds, heat waves, but it is something more common.
At least it wasn't another Katrina. It's the silver lining that many people seemed to cling to after Hurricane Barry (which was quickly downgraded to Tropical Storm Barry), which hit Louisiana on Saturday. The storm had modest wind speeds (120 km per hour compared to Katrina's 280), but still generated torrential rain, bypassing levees in several counties as it continued to pass through parts of Mississippi, Arkansas, Missouri and Tennessee at speeds of 16 km per hour.
Although the major storm underperformed most forecasts and moved more slowly, government officials continued to urge residents to be cautious. When it comes to extreme weather, something the vast majority of experts say we should expect more in the coming years, most people assume the biggest danger will be in the form of something new: record hurricane-force winds, off-the-charts waves. heat, or regional displacement conditions. But, as Barry showed, one of the most insidious effects of climate change could be something that most places are already somewhat familiar with: rain.
The past 12 months have been the wettest in US history Spring flooding drowned large swaths of the Midwest this year, destroying communities and essentially turning farms into inland seas. The floods overwhelmed levees in the heart of the country, drenching cities and causing billions of dollars in infrastructure and damage to crops. During May, a stormy pattern raised the monthly national average of precipitation to the second highest level on record, according to the National Oceanic and Atmospheric Administration. The seemingly endless rain proved to be a major climate threat and cause a chaotic maelstrom for farmers: farmers were able to plant just 58 percent of the corn crop (compared to 90 percent in the same period last year ), and this May's soybean planting was delayed by more than 30 percent.
Heavy rains can be as damaging to crops and cities as drought and extreme heat, and the US is set to experience more of both. This June, for example, a slow-moving storm dumped more than a month of rain in parts of the southeast, while the generally cold bay area (as Mark Twain put it, “the coldest winter I've ever seen) last is the summer in San Francisco ”). It reached a seasonal high of 38 degrees C.
In many regions with high rainfall, scientists predict that we will continue to see more extreme rainfall. As NOAA stated in a 2018 report, "Annual flood records are expected to break again next year and for years and decades to come."
More than 70 percent of the planet's surface is water, and as the world warms, more water evaporates from oceans, lakes, and soils. As average temperatures rise, the air acts like a sponge that can retain more moisture. For every 1 degree Celsius (or 1.8 degrees Fahrenheit) of heating, the air can hold 7 percent more water. That moisture then falls as extreme rain. Additionally, climate change causes storms to migrate at a slower rate, allowing them to drop much more rain in a given region, increasing the risk of devastating floods. In this way, climate change forms an ideal mix for perfect thunderstorms.
Take Hurricane Harvey as an example. When the storm approached the Texas coast nearly two years ago, it was clear that it would be one for the ages. It dumped more than 76 cm of rain on 6.9 million people, while 1.25 million experienced more than 1.14 cm and 11,000 had more than 1.27. The result was a catastrophic flood in the city and the surrounding area that caused approximately $ 128 billion in damage and killed 89 people. Four attribution studies have found that human-caused global warming likely exacerbated Harvey's rains.
"Harvey was the most important rainfall event in United States history in terms of rainfall range and totals since rainfall records began during the 1880s," wrote scientists from the United States Geological Survey in a study. last year.
In most recent memory, Hurricane Florence was left an unwanted guest after it slammed into North Carolina as a Category 4 beast last year. It unleashed an unprecedented average of 44.45 cm of rain in an area of 3.6 million hectares. At least 53 direct or indirect deaths were attributed to the storm. According to an experimental “pre-attribution” study, the first of its kind, conducted as the storm approached its peak, climate change caused the heaviest rains in Florence in North Carolina to be more than 50 percent in magnitude of what they would have been otherwise.
In addition to passing laws to reduce emissions, cities can invest in infrastructure to prevent future climate-related disasters. After Hurricane Katrina, New Orleans reinforced its levees and flood walls. New York City provided funding for a massive flood wall in the southern tip of Manhattan. Basically, other flood-prone metropolitan areas are making room for excess water: Chicago has built more than 100 "Green Alleys" - permeable pavement that allows stormwater to seep and drain into the ground. After Hurricane Sandy, Hoboken, NJ, rebuilt itself with future storms in mind, replacing concrete with spongy surfaces and installing a 757,000-gallon stormwater tank in one of the city's great parks.
People can also take individual precautions when they are actually dating. "Forecasts of heavy rain should be taken seriously," said Dr. David Novak of the NOAA Weather Prediction Center in a 2018 interview. He recommends being aware of your flood risks, such as living in a low-lying area. Knowing your evacuation routes and paying attention to official warnings is key to staying safe. "Most of the flood-related deaths occur in vehicles," he said. "It only takes a foot of water to sweep your vehicle."