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  • Global warming found to be culprit for flood risk in Peruvian Andes, other glacial lakes
    Thursday, February 4, 2021

    Huaraz is a Peruvian city of about 120,000 residents that lies 1.8 miles (3 kilometers) above sea level, in view of Palcaraju Glacier and other peaks in the Cordillera Blanca mountains.Wikimedia

    rooftops in front of glacier

    As the planet warms, glaciers are retreating and causing changes in the world's mountain water systems. For the first time, scientists at the University of Oxford and the University of Washington have directly linked human-induced climate change to the risk of flooding from a glacial lake known as one of the world's greatest flood risks.

    The study examined the case of Lake Palcacocha in the Peruvian Andes, which could cause flooding with devastating consequences for 120,000 residents in the city of Huaraz. The paper, published Feb. 4 in Nature Geoscience, provides new evidence for an ongoing legal case that hinges on the link between greenhouse gas emissions and particular climate change impacts.

    "The scientific challenge was to provide the clearest and cleanest assessment of the physical linkages between climate change and the changing flood hazard," said co-author Gerard Roe, a UW professor of Earth and space sciences.

    In 2016, Roe and colleagues developed a method to determine whether an individual glacier's retreat can be linked to human-induced climate change. The retreat of mountain glaciers has several consequences, including creating basins in the space left by the retreating glacier. Precipitation and meltwater collects in these basins to form glacial lakes. Recent work has shown a rapid worldwide growth in the number and size of high-elevation glacial lakes.

    "We believe our study is the first to assess the full set of linkages between anthropogenic climate change and the changing glacial lake outburst flood hazard," Roe said. "The methods used in our study can certainly be applied to other glacial lakes around the world."

    green lake with glacier behind

    Lake Palcacocha last burst its banks in 1941, killing at least 1,800 people in the city of Huaraz. Known as one of the world's most dangerous lakes, its water level has risen in recent years with the shrinking of Palcaraju Glacier, which lies directly to the north.Georg Kaser/Wikimedia

    The new study first calculated the role of human emissions in the observed temperature increase since the start of the industrial era around Palcaraju Glacier. It finds that human activity is responsible for 95% of the observed 1 degree Celsius (1.8 degrees Fahrenheit) warming in this region since 1880.

    The authors then used the UW-developed technique to assess the relationship between these warming temperatures and the observed long-term retreat of the glacier that has caused Lake Palcacocha to expand. Results show it is virtually certain, with greater than 99% probability, that human-induced climate change has caused Palcaraju Glacier's retreat.

    Lead author Rupert Stuart-Smith, a doctoral student at Oxford, then used two methods to assess the hazard of glacial lake outburst flooding, in which an avalanche, landslide or rockfall induces a tsunami wave that overtops the lake's banks, to pinpoint how Lake Palcacocha's growth affects the flood risk faced by the city of Huaraz below.

    grid of aerial views of growing lake

    Historical photographs (first three panels) and satellite images show how Lake Palcacocha has grown as the glacier has receded. The lake is now about 34 times its volume in 1970.Stuart-Smith et al./Nature Geoscience

    "We found that human influence on climate -- through greenhouse-gas emissions -- is responsible for virtually all of the warming that has been observed in the region," said Stuart-Smith, who spent the summer of 2019 at the UW. "The study shows that warming has caused the retreat of the Palcaraju Glacier, which in turn has greatly increased the flood risk."

    The study provides new evidence for an ongoing case in the German courts in which Sa?l Luciano Lliuya, a farmer from Huaraz, has sued RWE, Germany's largest electricity producer, for its role in creating global warming. The suit seeks reimbursement for current and future flood-risk reduction measures.

    "Crucially, our findings establish a direct link between emissions and the need to implement protective measures now, as well as any damages caused by flooding in the future," Stuart-Smith said.

    Nature Geoscience editorial: “Mountains of change

    This is not the first time Huaraz has been threatened by climate change. In 1941, an outburst flood from Lake Palcacocha, resulting from an ice and rock slide, killed at least 1,800 people. The study also found this flood to be influenced by human-induced climate change -- making it one of the earliest identified fatal impacts of climate change.

    The lake's recent growth strains decades of engineering efforts since the 1970s to contain the lake's water.

    "Around the world, the retreat of mountain glaciers is one of the clearest indicators of climate change," Roe said. "Outburst floods threaten communities in many mountainous regions, but this risk is particularly severe in Huaraz, as well as elsewhere in the Andes and in countries like Nepal and Bhutan, where vulnerable populations live in the path of the potential floodwaters."

    Other co-authors are Myles Allen and Sihan Li at the University of Oxford. The study was funded by the U.K. Natural Environment Research Council, the U.S. National Science Foundation and a grant from the University of Oxford.

     

    For more information, contact Roe at groe@uw.edu or Stuart-Smith at rupert.stuart-smith@ouce.ox.ac.uk.

    Adapted from a University of Oxford article.

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  • Seismic Network monitors recent tremor under Vancouver Island | Bellingham Herald
    Tuesday, February 2, 2021
    The UW-based Pacific Northwest Seismic Network is monitoring an "out of the ordinary" series of nearly 3,000 small seismic events over the past week that have rattled just northwest of Whatcom County under Vancouver Island. Steve Malone, emeritus research professor of Earth and space sciences at the UW, is quoted. Read More
  • Podcast: How Mount Rainier will tell us when it's going to blow | Crosscut
    Monday, January 25, 2021
    Looming on the horizon like a holographic ice cream cone, Mount Rainier draws eyes skyward everywhere in Puget Sound. But fear mingles with our fascination: Is it going to blow? And if so, when? Harold Tobin, director of the Pacific Northwest Seismic Network and professor of Earth and space sciences at the UW, is interviewed on the "Crosscut Escapes" podcast. [Interview begins at 9:35] Read More
  • Robert Winglee, 1958-2020: UW's 'Rocket Man' launched thousands of space and science careers | GeekWire
    Sunday, January 24, 2021
    The global aerospace community and students across the Northwest have lost a researcher, mentor and "Rocket Man" who inspired and guided thousands of young people toward careers in the stars. That's what colleagues and friends of the late Robert Winglee, professor of Earth and space sciences at the UW, said during a virtual memorial service held last weekend. The UW's Roger Buick, professor of Earth and space sciences, and Irene Svete, a public information specialist at the Washington NASA Space Grant Consortium, are quoted. Read More
  • Relentless rain triggers landslides; more rain and risk on the way | KIRO 7
    Monday, January 4, 2021
    Days of heavy rain in Western Washington has communities on high alert. Storms have already triggered small landslides, and geologists say conditions are ripe for the next storm coming Tuesday to spur additional slides. David Montgomery, professor of Earth and space sciences at the UW, is interviewed. Read More
  • Salty seas make lightning brighter | Hakai Magazine
    Monday, January 4, 2021
    Salt seems to be the reason why bolts are brighter over the ocean than over land. Robert Holzworth, professor of Earth and space sciences at the UW, is quoted. Read More
  • 3rd small earthquake hits Puget Sound area | The Seattle Times
    Sunday, January 3, 2021
    A small earthquake with a magnitude of 3.0 was reported near Carnation on Tuesday morning, one day after a smaller magnitude 2.2 quake was reported in the same location on Monday, according to the UW-based Pacific Northwest Seismic Network. Harold Tobin, director of the Pacific Northwest Seismic Network and professor of Earth and space sciences at the UW, is quoted. Read More
  • Small earthquake near Monroe follows other recent minor quakes in the Puget Sound area | The Seattle Times
    Monday, December 28, 2020
    A magnitude 2.9 earthquake was recorded about four miles from Monroe at 2:41 a.m. Monday, according to the Pacific Northwest Seismic Network. Ken Creager, professor of Earth and space sciences at the UW, is quoted. Read More
  • WWLLN detects increasing lightning in the Arctic as Earth warms
    Thursday, December 17, 2020
    Nature magazine reports on the AGU ( American Geophysical Union) paper presented this year by ESS Professors Holzworth,and McCarthy, senior scientist Jacobson, Grad student Todd Anderson, and collaborators Dr. James Brundell and Dr. Craig Rodger of the University of Otago, Dunedin, New Zealand. The authors found that the fraction of global lightning occurring north of 65 degrees has greatly increased in the last decade, and varies with the global temperature anomaly. They predict a 100% increase in Arctic lightning by the time the Earth warms another 0.5 degrees Centigrade. Read More
  • An ice core from the roof of the world | Eos
    Monday, December 14, 2020
    An innovative National Geographic expedition collected the world's highest ice core from Mount Everest. Eric Steig, professor of Earth and space sciences at the UW, is quoted. Read More