How the floods and heatwaves of 2021 are signs of what’s to come
In 2021, extremely rare weather disasters have become extremely common.
In Tennessee, towns were inundated with 17 inches of rain over two days. Dozens of people drowned in basement apartments and cars in New Jersey, when floodwaters increased as the remnants of Hurricane Ida swept through. Heat-related illnesses in the Pacific Northwest sent nearly 3,000 people to the emergency room when temperatures rose above 116 degrees.
All of them are considered to be a 1000-year event, with only a 0.1% chance of occurring in any given year. But as global temperatures rise, these types of extremes occur more frequently.
Like two sides of the same coin, rising temperatures make dry heat waves more intense, while causing storms that trigger larger downpours. Climatologists expect this trend to intensify as humans continue to release heat-trapping gases into the atmosphere.
Whether it was too much water or too much heat, the extreme weather events of 2021 revealed major gaps in the preparedness of cities and governments to deal with them. Most of the country’s homes, roads, and public safety systems were designed for the climate of the last century, when the most extreme weather events happening today were considered unlikely.
“I think the biggest lesson is that the past is not a good predictor of the future and to start planning now what the climate might be 20 or 30 years from now,” says David Easterling, climate scientist at the National Oceanic and Atmospheric Administration. (NOAA).
In late June, the weather forecast for Washington and Oregon looked like something written for the deserts of the southwest. Temperatures topped 110 degrees, well in record territory. An area of high pressure known as the thermal dome traps dangerously hot air over the region, deflecting the clouds and cool breezes the region is used to.
With many residents without air conditioning, the heat has become a public health emergency. Thousands of people have gone to the hospital and more than 200 people died. The paved surfaces have become dangerously hot. Roads and infrastructure sail. The effects were even worse in cities, where cement absorbs and radiates heat, pushing temperatures even higher.
As the climate warms, episodes of extreme heat are increasingly likely. Globally, temperatures have already risen by almost 2 degrees Fahrenheit (1.1 degrees Celsius). If temperatures reach 3.6 degrees Fahrenheit warming (2 degrees Celsius), scientists predict a heat wave in 50 years is almost 14 times more likely to occur, according to a big climate balance published this year by the Intergovernmental Panel on Climate Change (IPCC).
While climatologists have followed these general trends for decades, they are now also looking at how climate change is intensifying individual heat waves. According to a study by scientists from Global weather attribution collaborative, the Pacific Northwest heat wave was 150 times more likely by climate change. In other new report, the American Meteorological Society (AMS) found that climate change also influenced many of the heatwaves of 2020.
“At this point, understanding the role of climate change in a heat wave has become routine,” says Stephanie Herring, a NOAA climatologist who worked on the AMS report. “All over the world, it is extremely rare to find a heat event that is not aggravated, to some extent, by climate change. “
Just six months after the summer heatwave, British Columbia and the Pacific Northwest found themselves facing yet another extreme climate. An intense winter storm flooded roads and homes, one of many rain-triggered disasters this year that have shown how quickly cities can be overcome by water.
In August, heavy rainfall in Waverly, Tennessee led to rapid flash floods, damaging hundreds of homes and killing more than 20 people. The 17 inches of rain was way beyond the limits of an extreme storm for the region, even more unlikely than an event over 1000 years.
Later in the month, the remnants of Hurricane Ida raging heavy rains across the northeast, blowing away many residents. As the streets filled with water, some were trapped in basement apartments and drowned. Others were caught in their cars. Authorities have pledged to increase flood warnings and go door-to-door for evacuations in the future.
While every storm is different, rising temperatures are already increasing the ability of storms to release more intense rains.
“Unfortunately, we’re starting to see more and more of this precipitation,” Easterling said. “And in the future, due to warming, a warmer atmosphere is expected to hold a lot more moisture and these events will continue to increase.”
In most of the United States, the biggest storms already produce more rain. In the northeast, these storms produces 55% more rain by 2016, compared to 1958, according to the latest national climate assessment. Overall, the recent IPCC assessment finds that heavy storms will be 14% wetter if the planet warms to 3.6 degrees Fahrenheit (2 degrees Celsius).
Most cities, including stormwater systems that drain water, are not designed to handle the most extreme storms. Building infrastructure to handle the heaviest rains can be costly. But while these storms were once considered rare, climate change is changing the equation.
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