新澳门六合彩内幕信息

Losing Winter

Amid Snow and Ice Declines, What Happens to Sierra Lakes in the Winter?

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Ireland Lake in California鈥檚 Sierra Nevada is among the small alpine lakes 新澳门六合彩内幕信息 Davis researchers monitored to learn about how the lakes behave in the winter. (Adrianne Smits/新澳门六合彩内幕信息 Davis)
Ireland Lake in California鈥檚 Sierra Nevada is among the small alpine lakes 新澳门六合彩内幕信息 Davis researchers monitored to learn about how the lakes behave in the winter. (Adrianne Smits/新澳门六合彩内幕信息 Davis)

Quick Summary

  • Scientists placed a network of sensors in remote mountain lakes to learn how the lakes spend their winter
  • Study is the first to look at ice cover and under-ice conditions in small Sierra Nevada lakes

How small mountain lakes spend their winters is largely unknown to scientists, despite winter representing nearly half the year in such environments. A study by the University of California, Davis, helps demystify what happens above and below the ice. 

, published in a of the Journal of Geophysical Research: Biogeosciences, is the first to look at ice cover and under-ice conditions in small Sierra Nevada lakes, which number in the thousands.

Such baseline knowledge is critical for understanding how high-elevation lakes respond to climate change and to the loss of ice and snow. Despite heavy snowfall this winter, climate projections estimate the Sierra snowpack could drastically shrink or even disappear by 2100.

鈥淲inter is a big part of the year. We don鈥檛 understand it, and we鈥檙e losing it,鈥 said lead author Adrianne Smits, a National Science Foundation postdoctoral scholar at 新澳门六合彩内幕信息 Davis. 鈥淟akes in many cold regions of the world are losing ice cover fast, and very few studies examine what happens to them in winter. People assume they鈥檙e hibernating or dead, and the more we learn, we find that鈥檚 completely false.鈥 

A small alpine lake surrounded by gray mountains in the Sierra Nevada of California
Small alpine lakes like Ruby Lake, shown here in 2018, respond differently than larger lakes to changes in loss of ice and snow. (Adrianne Smits/新澳门六合彩内幕信息 Davis)

A sense of snow

For the study, researchers placed a network of underwater sensors in 15 remote mountain lakes throughout the Sierra Nevada to try to understand what type of lakes may be the most sensitive to loss of snow and ice cover. Placed during the more accessible warmer months, the sensors took hourly measurements of water temperature, dissolved oxygen, the timing of ice formation and breakup, and other climate variables for up to five winters.

The study found that most mountain lakes will have shorter ice cover, warmer water and higher oxygen concentrations as winters warm. But small and large lakes will respond differently to the loss of ice cover and snow, with small lakes being more susceptible to changes between wet and dry years.

Other findings include:

  • Snowfall and air temperature determine when ice breaks up and how long it lasts.
  • Lake size and shape control oxygen and temperature immediately after ice forms, but late winter conditions depend on other variables that dictate how long ice covers the lake.
  • Small, shallow lakes experience low-oxygen conditions more so than large, deep lakes. However, shallow lakes are also more dynamic because heavy snowfall causes ice to submerge, changing oxygen levels as water is displaced by ice.

The findings can help inform conservation management related to water resources, endangered and threatened species, and summer algal blooms, which thrive in years with early ice breakup.

鈥淲e are used to mountain lakes being crystal clear, but they are likely to become increasingly 鈥榞reen,鈥 with large algae blooms around the shoreline,鈥 Smits said.

Remote work

At least 12,000 small lakes are scattered throughout the slopes and valleys of the Sierra Nevada. Getting to them is challenging even when not socked in with ice and snow 鈥 a key reason they are understudied.

For Smits, a typical field visit included an all-day drive, then backpacking 8 to 15 miles each way while carrying more than 50 pounds of gear. In addition to the data, she was rewarded with spectacular views and a landscape few others experience.

One of the more arduous treks became Smits鈥 favorite site, Boundary Lake, along the edge of Yosemite National Park. She saw it in lush, wet years and in dry years with smoke-filled air. Remnants of the Rim Fire made the hike a slog through broken trail and a scramble into the forest. But at the end was a quiet beauty under a blue and pink-streaked sky that she had all to herself.

鈥淚t鈥檚 really amazing to be able to go to places like that for work,鈥 said Smits, who is also an artist whose are clearly inspired by a love for the natural world. 鈥淭hese lakes are beautiful and all different in their own way. I used to think the Sierra was just pine trees and granite, but that鈥檚 not the case.鈥

Topaz Lake glistens under a sky of dramaitc, sweeping clouds in the Sierra Nevada mountain range. A small boat is a speck on the water.
Topaz Lake glistens under a dramatic, cloud-swept sky in California. (Steven Sadro/新澳门六合彩内幕信息 Davis)

On the record

The network includes two long-term study sites: Castle Lake, which 新澳门六合彩内幕信息 Davis limnologist Charles Goldman began studying more than 50 years ago, and Emerald Lake, studied since the 1980s by the study鈥檚 senior author Steven Sadro, a 新澳门六合彩内幕信息 Davis professor in the Department of Environmental Science and Policy. The sites anchor points tied through time, creating a historic record that can greatly inform climate research.

鈥淲e know climate change is causing ice cover to decrease,鈥 Sadro said. 鈥淲hat are the implications of that? What is the climate sensitivity of lakes? It鈥檚 not a one-paper answer. This will be at least a decade of work to characterize the basic function in the lakes. But we鈥檙e learning more that will help us make more accurate predictions about why and how the system will change.鈥

Additional co-authors include Nicholas W. Gomez of 新澳门六合彩内幕信息 Davis and Jeff Dozier of 新澳门六合彩内幕信息 Santa Barbara.

The study was funded by the National Science Foundation鈥檚 Division of Earth Sciences.

This study and several others contributed by Sadro and Smits in the winter limnology special issue of JGR: Biogeosciences stemmed from the American Geophysical Union鈥檚 , 鈥淲inter Limnology in a Changing World,鈥 held in 2019.

Media Resources

Media Contacts:

  • Adrianne Smits, 新澳门六合彩内幕信息 Davis Environmental Science and Policy, adriannesmits@gmail.com
  • Steven Sadro, 新澳门六合彩内幕信息 Davis Environmental Science and Policy, ssadro@ucdavis.edu
  • Kat Kerlin, 新澳门六合彩内幕信息 Davis News and Media Relations, 530-750-9195, kekerlin@ucdavis.edu

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