The research builds upon a previous snowpack investigation by the U.S. Geological Survey (USGS) that showed that, until the 1980s, the northern Rocky Mountains experienced large snowpacks when the central and southern Rockies experienced meager ones, and vice versa.
Yet, since the 1980s, there have been simultaneous snowpack declines along the entire length of the Rocky Mountains, and unusually severe declines in the north, the earlier investigation showed.
Now, the new study, also by USGS scientists, has teased apart and quantified the different influences of winter temperature, spring temperature, and precipitation on historic snowpack variations and trends in the region. To distinguish those varying influences, the researchers implemented a regional snow model that uses inputs of monthly temperature and precipitation data from 1895 to 2011.
“Each year we looked at temperature and precipitation variations and the amount of water contained within the snowpack as of April,” said Greg Pederson of the USGS Northern Rocky Mountain Science Center in Bozeman, Mont., who is the lead author of the study. “Snow deficits were consistent throughout the Rockies due to the lack of precipitation during the cool seasons during the 1930s – coinciding with the Dust Bowl era. From 1980 on, warmer spring temperatures melted snowpack throughout the Rockies early, regardless of winter precipitation. The model in turn shows temperature as the major driving factor in snowpack declines over the past thirty years.”
Pederson and his colleagues present their new findings in an article in Geophysical Research Letters, a journal of the American Geophysical Union.
Runoff from Rocky Mountain winter snowpack accounts for 60 to 80 percent of the annual water supply for more than 70 million people living in the western U.S., and is influenced by the snowpack’s water content, known as snow water equivalent, and the timing of snowmelt.
The timing of snowmelt affects not only when water is available for crop irrigation and energy production from hydroelectric dams, but also the risk of regional floods and wildfires. Earlier and faster snowmelt could have repercussions for water supply, risk management, and ecosystem health in western watersheds.
Regional snowpack accumulation is highly sensitive to variations in both temperature and precipitation over time. Patterns and sources of these variations are difficult to discern due to complex mountain topography, the different influence of Pacific Ocean climate, like La Niña and El Niño, on winter precipitation in the northern versus southern and central Rockies, and the brevity and patchiness of detailed snow records.
In the new study, the regional snow model used by Pederson and his USGS colleagues Julio Betancourt, and Greg McCabe allows estimation of snow water and cover variability at different latitudes and elevations during the last century regardless of the absence of direct and long-term observations everywhere. Recent snowpack variations also were evaluated in the context of snowpack evidence from tree-rings, allowing the scientists to compare recent observations to measurements from the past 800 years.
McCabe explains that “recent springtime warming also reduced the extent of snow cover at low to middle elevations where temperature has had the greatest impact.”
“Both natural variability in temperature and anthropogenic warming have contributed to the recent snowpack decline, though disentangling their influences exactly remains elusive,” Betancourt said. “Regardless of the ultimate causes, continuation of present snowpack trends in the Rocky Mountains will pose difficult challenges for watershed management and conventional water planning in the American West.”
Notes for Journalists
Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this accepted article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/grl.50424/abstract
Or, you may order a copy of the paper by emailing your request to Peter Weiss at email@example.com. Please provide your name, the name of your publication, and your phone number.
Neither the paper nor this press release are under embargo.
“Regional patterns and proximal causes of the recent snowpack decline in the Rocky Mountains, U.S.”Authors:
Peter Weiss | American Geophysical Union
Further reports about: > American Geophysical Union > Geological > Geological Survey > Mountain Bike > Mountains > Pacific Ocean > Rockies > Rocky Mountain winter snowpack > Rocky Mountains > anthropogenic warming > conventional water planning > ecosystem health > regional floods > water supply > watershed management
New plate adds plot twist to ancient tectonic tale
15.08.2017 | Rice University
Global warming will leave different fingerprints on global subtropical anticyclones
14.08.2017 | Institute of Atmospheric Physics, Chinese Academy of Sciences
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).
The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
16.08.2017 | Physics and Astronomy
16.08.2017 | Materials Sciences
16.08.2017 | Interdisciplinary Research