Division of Resources Management and Science Yosemite National Park 2012-2015 Drought Impacts to the Lyell and Maclure Glaciers Greg Stock1, Harrison Forrester1, Thomas Painter2, Robert S. Anderson3 1National Park Service, Yosemite National Park 2NASA Jet Propulsion Laboratory, California Institute of Technology 3University of Colorado, Boulder Lyell Glacier West Lyell Glacier East Maclure Glacier Photo: Austin Post, USGS 1972 Photo: Jonathan Byers, AAP 2014 John Muir’s 1872 measurement of glacier movement John Muir Galen Clark Joseph LeConte “The Maclure Glacier seemed best fitted for my purpose, and, with the assistance of my friend Galen Clark, I planted five stakes in it on the 21st of August, 1872, guarding against their being melted out by sinking them to a depth of five feet On the 6th of October, or forty-six days after being planted, I found the [maximum] displacement to be forty-seven inches in forty-six days, or about one inch per twenty-four hours.” John Muir, 1875, “Living Glaciers of California”, Harper’s New Monthly Magazine US Geological Survey research (1883-1903) Israel Russell Map of the Lyell and Maclure glaciers by W.D Johnson in Russell (1989) Quaternary History of the Mono Valley US Geological Survey research (1883-1903) Photograph of the East Lobe Lyell Glacier by I.C. Russell, circa 1883 National Park Service glacier surveys (1931-1975) National Park Service glacier surveys (1931-1975) National Park Service glacier surveys (2006-2015) Jonathan Byers Maclure Glacier surface velocities • Between 2009 and 2012, the Maclure Glacier moved about 7 m per year • Between 21 August and 6 October 2012, the maximum displacement was 2.6 cm (about one inch) per twenty-four hours (!) Photo: Keenan Takahashi 1883 2013 1903 Photo Jonathan 2013Byers 2009 2015 2010 Photo Jonathan Byers Photo: ParkerDavis Photo: 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 Lyell and Maclure glacier retreat, 1883 - 2015 ASO-based measurements of volume change Repeat measurements of “snow off” topography allow for calculating change in glacier ice volume Glacier loss expected to: • Decrease late summer streamflows • Increase water temperatures • Impact downstream aquatic and riparian ecosystems Implications for Tuolumne River flows Data courtesy Mike Dettinger and Jessica Lundquist Implications for Tuolumne River flows Data courtesy Mike Dettinger and Jessica Lundquist Summary • Lyell and Maclure glaciers have lost ~80% of their surface area since 1883; 12% of that has occurred during the 2012-2015 drought • If present trends continue, Lyell Glacier will be gone in 5 years • Glacier loss will likely profoundly affect late summer/fall flows in the Upper Tuolumne River.