Extreme storms

As rising global temperatures make extreme storms more common, the nation’s dams and reservoirs – crucial to keeping communities dry – are being tested. Storms in the U.S. Northeast stretched the region’s flood control systems nearly to the breaking point in July 2023. California and states along the Mississippi River faced similar flood control challenges in 2023. Managing these flood control systems is a careful balancing act. Do managers release water to make room for the storm’s runoff, increasing the risk of flooding downstream, or hold as much as possible to protect downstream farms and communities, which could increase the chance of larger floods if another storm comes through? The earlier decisions can be made, the better the chance of avoiding downstream damage. But forecasts aren’t always reliable, and waiting for the rain to fall may mean acting too late. Satellite water vapor imagery from July 9-11, 20...

Honolulu has lost more than 5 miles of its famous beaches to sea level rise and storm surges. Sunny-day flooding during high tides makes many city roads impassable, and water mains for the public drinking water system are corroding from saltwater because of sea level rise. The damage has left the city and county spending millions of dollars on repairs and infrastructure to try to adapt to the rising risks. Future costs will almost certainly be higher. More than US$19 billion in property value, at today’s dollars, is at risk by 2100 from projected sea level rise, driven by greenhouse gas emissions largely from the burning of fossil fuels. Elsewhere in Honolulu County, which covers all of Oahu, many coastal communities will be cut off or uninhabitable. Unwilling to have their taxpayers bear the full brunt of these costs, the city and county sued Sunoco LP, Exxon Mobil Corp. and other big oil companies in 2020. Their case – one of more than two dozen involving U.S. ci...

To get a sense of the enormous amount of water atmospheric rivers dumped on the Western U.S. this year and the magnitude of the flood risk ahead, take a look at California’s Central Valley, where about a quarter of the nation’s food is grown. This region was once home to the largest freshwater lake west of the Rockies. But the rivers that fed Tulare Lake were dammed and diverted long ago, leaving it nearly dry by 1920. Farmers have been growing food on the fertile lake bed for decades. This year, however, Tulare Lake is remerging. Runoff and snowmelt from the Sierra Nevada have overwhelmed waterways and flooded farms and orchards. After similar storms in 1983, the lake covered more than 100 square miles, and scientists say this year’s precipitation is looking a lot like 1983. Communities there and across the West are preparing for flooding and mudslide disasters as record snow begins to melt. Tulare Lake, long dry, begi...

Reading the latest international climate report can feel overwhelming. It describes how rising temperatures caused by increasing greenhouse gas emissions from human activities are having rapid, widespread effects on the weather, climate and ecosystems in every region of the planet, and it says the risks are escalating faster than scientists expected. Global temperatures are now 1.1 degree Celsius (2 degrees Fahrenheit) warmer than at the start of the industrial era. Heat waves, storms, fires and floods are harming humans and ecosystems. Hundreds of species have disappeared from regions as temperatures rise, and climate change is causing irreversible changes to sea ice, oceans and glaciers. In some areas, it’s becoming harder to adapt to the changes, the authors write. Still, there are reasons for optimism – falling renewable energy costs are starting to transform the power sector, for example, and the use of electric vehicles is expanding. But change aren’t hap...

Atmospheric rivers, those long, powerful streams of moisture in the sky, are becoming more frequent in the Arctic, and they’re helping to drive dramatic shrinking of the Arctic’s sea ice cover. While less ice might have some benefits – it would allow more shipping in winter and access to minerals – sea ice loss also contributes to global warming and to extreme storms that cause economic damage well beyond the Arctic. I’m an atmospheric scientist. In a new study of the Barents-Kara Seas and the neighboring central Arctic, published Feb. 6, 2023, in Nature Climate Change, my colleagues and I found that these storms reached this region more often and were responsible for over a third of the region’s early winter sea ice decline since 1979. More frequent atmospheric rivers By early winter, the temperature in most of the Arctic is well below freezing and the days are mostly dark. Sea ice should be growing and spreading over a wider area. Yet the...