Latest news with #MendenhallValley
The Guardian
4 days ago
- Climate
- The Guardian
Alaska's Juneau orders evacuations as record glacier flood looms
Alaska's capital city of Juneau is urging many residents to evacuate, bracing for the arrival of what could be record floodwaters flowing downstream from a basin dammed by the area's Mendenhall Glacier, with the event being driven by climate change amid glacial retreat, according to a federal agency. Summer glacial flooding, known as a glacial lake outburst flood, or GLOF, threatens parts of the city due to a combination of rainwater and snowmelt. Authorities say flooding from the Mendenhall River will likely crest around 4pm Alaska time, or 8pm ET on Wednesday. They hope that recently installed emergency flood barriers will hold back the waters and protect Mendenhall Valley, where a majority of Juneau's 32,000 full-time residents live. On Tuesday morning, authorities confirmed water had started escaping the ice dam, with flooding expected into Wednesday. Some Juneau residents in the flood zone have already evacuated as officials intensified their warnings Tuesday, saying 'Don't wait, Evacuate TONIGHT.' The National Weather Service (NWS) office in Juneau said in an X post late Tuesday that local hydrologists had adjusted their Mendenhall flooding forecast, anticipating that the river would crest at over 16ft on Wednesday morning. Nicole Ferrin, with the NWS, said during a briefing on Tuesday that the flood warning was issued after 'a lot of analysis' but the calculations were complicated by rainfall causing significant rising of the lake and river and confirmed that a sub-glacial release had occurred. 'This will be a new record based on all of the information we have,' Ferrin said, according to the Juneau Empire. The Mendenhall Glacier fills a large valley north of Juneau, creating an ice dam for a meltwater lake that fills Suicide Basin. Since 2011, outburst floods from the depression have been pouring into Mendenhall Lake and rushing down the river toward Juneau each year. But the annual Mendenhall glacial lake outburst flood is judged to be intensifying as a result of climate change. The National Oceanic and Atmospheric Association (Noaa), said in a statement that Alaska has warmed twice as fast as the rest of the US over the last several decades. Over the last century Alaska's average annual temperature has risen 3.1 degrees Fahrenheit and the overall trend continues to increase, according to data from Noaa's National Centers for Environmental Information. Scientists have attributed the retreat, melting and thinning of glaciers over the last century to Earth's warming climate. Alaska's glaciers are among the fastest melting glaciers on Earth and have been in steep decline since the late 1980s, according to the Alaska Climate Science Center. On the record amounts of water now threatening Juneau, Rick Thoman, Alaska climate specialist at the Alaska Center for Climate Assessment and Policy, told Noaa reported: 'Without climate change, there is no reason to think that this would be happening on the Mendenhall Glacier, then in the lake, and downriver.' An outburst in August 2023 sent record amounts of water into Mendenhall Lake and down Mendenhall River toward Juneau, inundating areas that had not experienced flooding before, the NWS office in Juneau said at the time, causing significant erosion. The Mendenhall Glacier is about 12 miles from Juneau and considered a popular tourist attraction. Juneau lies 800 miles from Anchorage, where Donald Trump and Russian president Vladimir Putin are due to meet on Friday to discuss the war in Ukraine. Flooding from the glacier has become an annual concern for almost 15 years, and in recent years has swept away houses and swamped hundreds of homes. It is blamed on the retreat of a smaller glacier near Mendenhall Glacier – a casualty of the heating climate – and left a basin that fills with rainwater and snowmelt each spring and summer. When the water creates enough pressure, it forces its way under or around the ice dam created by the blue ice Mendenhall glacier. The Mendenhall was originally named Sitaantaagu ('the Glacier Behind the Town') or Aak'wtaaksit ('the Glacier Behind the Little Lake') by the Tlingit Indians, but later called Auke (Auk) Glacier, for the Auk Kwaan band of Tlingit Indians, by naturalist John Muir. It was renamed in 1892 for Thomas Corwin Mendenhall, who had helped determine the boundary between Canada and Alaska. It is considered a relic of the little ice age that lasted until the mid-18th century and is now receding at about 100 to 150 feet a year. The Associated Press contributed reporting.
Yahoo
4 days ago
- Climate
- Yahoo
Alaska capital Juneau urged to evacuate as 'glacial outburst' flood looms
Emergency managers are urging many residents of Alaska's capital city of Juneau to evacuate as summer glacial flooding driven by climate change threatens to inundate the area. Authorities say flooding from the Mendenhall River will likely crest around 4 p.m. Alaska time on Aug. 13, or 8 p.m. Eastern. They hope two miles worth of emergency flood barriers they finished intalling last month will hold back the waters from Mendenhall Valley, where a majority of Juneau's 32,000 full-time residents live. "Residents are advised to evacuate the potential flood inundation area," City and Borough of Juneau officials said in a message Aug. 12. "Do not go near the river." Gov. Mike Dunleavy has also issued a preemptive disaster declaration, citing the devastation caused by "glacial outbursts" in both 2023 and 2024. As of noon Alaska time on Aug. 12, the Mendenhall River in Juneau had risen to 10 feet deep from its usual level of about 5 feet, crossing into "moderate" flood stage territory, the National Weather Service reported. The record set last year is 16 feet deep, and forecasters say the river could surpass that. Forecasters estimate 14.6 billion gallons of water were released during last year's flood, enough to fill more than 22,000 Olympic-sized swimming pools, according to the weather service. Previous years floods have swamped basements, destroyed infrastructure and collapsed buildings near the riverbanks. A glacial outburst like this occurs when an ice dam holding back a lake - in this case Suicide Basin - collapses from the summer heat, releasing the water in a short period of time. Suicide Basin is part of the Mendenhall Glacier, a popular tourist destination easily reached from Juneau. Federal scientists say climate change is causing the glacier to melt faster, along with altering rainfall patterns, exacerbating the danger. The first recorded outburst flood from the glacier happened 2011, according to the National Weather Service. Because the flooding has been a growing concern for Juneau over the past several years, city officials with federal assistance installed emergency flood barriers along several miles of riverbanks in the areas deemed most at risk for being overtopped. Although the new barriers are designed to hold back a flood of this potential magnitude, officials have asked residents to evacuate as a precaution. Compared to the rest of the country, Alaska has warmed twice as fast over the last several decades, and its average annual temperature has risen 3.1 degrees Fahrenheit in the past century, according to the federal National Centers for Environmental Information. This article originally appeared on USA TODAY: 'Glacial outburst' threatens Alaska city, prompts evacuations
