IPCC report demonstrates how melting snow in mountains affects water quantity — The Daily Californian

The Arapaho Glacier is the largest in Colorado and a key component of Boulder’s water supply. Over the last 100 years, it has receded dramatically, and climate researcher P. Thompson Davis worries it could disappear completely. Photo credit: American Alpine Club via the Colorado Sun

From The Daily Californian (Maxine Mouly):

For the first time since 1996, the United Nations’ Intergovernmental Panel on Climate Change, or IPCC, has dedicated a chapter to mountains in one of its reports.

One of the lead authors of the report is Heidi Steltzer, a member of the Department of Energy’s Watershed Function Scientific Focus Area at Lawrence Berkeley National Laboratory and professor of biology at Fort Lewis College in Colorado. According to her, the chapter in the report focuses on where and how the cryosphere — any part of the planet with a significant amount of frozen water — in mountains is changing.

Steltzer said she has been explaining the language of her study on social media, and Merriam-Webster posted an article that said it is watching the word “cryosphere” and is considering adding the word to the dictionary. Steltzer added that the IPCC made a “bold move” to use “cryosphere” in the name of the report, because most people are not familiar with the term.

“We can now start to talk holistically about one of the spheres of our planet,” Steltzer said. “The frozen parts of our world where there’s frozen water … that’s a huge move forward, because language can sometimes limit our understanding of something.”

In a recent report by the IPCC, the Special Report on the Ocean and Cryosphere in a Changing Climate used the latest scientific literature to describe climate change’s impacts on the ocean and cryosphere.

Melting glaciers, snow and permafrost morph the cryosphere in mountains because of climate change. This reduced snowpack occurs in the habitats of ice-dependent species and in watershed sources for humans. With less snow, there is less water available on an annual basis.

The population of the western United States is reliant on water from melting snow to fill reservoirs that are used for the remainder of the year, according to Kenneth Williams, the deputy director of the Watershed Function Scientific Focus Area at Berkeley Lab. He added that people view mountain snowpacks as the “water towers of the world.”

“Decisions need to be made about water utilization, because that annual water tower will not be filling up the same way it once did,” Williams said.

Steltzer said she wants to continue studying and understanding the climate systems. She added that we are seeing impacts due to climate change that we can feel and that are in the media.

“We don’t need to look to the future, climate change is here, it’s happening now, and we can start to ask questions and understand it better,” Steltzer said. “We need to act now to adapt and mitigate for climate change more than we need more data.”

Research by the DOE Watershed Function SFA project team takes place year-round in a research area along the East River catchment near the Upper Colorado River headwaters. One of the busiest times for sampling is during peak snow. (Photo courtesy Watershed Function SFA)

From the Lawrence Berkeley National Laboratory (Christina Procopiou):

The image of huge chunks of ice breaking away from glaciers and ice sheets, then floating out to sea in Earth’s most remote places, may be the most iconic symbol of a warming planet. And while most people will never see these familiar phenomena up close, what’s happening within some of the iciest settings still affects people and regions thousands of miles away.

Ecologist Heidi Steltzer, a Fort Lewis College professor and member of the Department of Energy’s Watershed Function Scientific Focus Area (SFA) project led by Lawrence Berkeley National Laboratory, studies how reduced snowpack and earlier snowmelt caused by climate change impact water supply in high-mountain areas. She is a lead author of a new report by the Intergovernmental Panel on Climate Change (IPCC), the United Nations body for assessing the science related to climate change. The Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) assesses the latest scientific literature to describe the impacts of climate change on the ocean and cryosphere – water in its solid state, which in mountains includes glaciers, permafrost, and snow.

Steltzer drew upon experience working in the Rocky Mountains of Colorado near the headwaters of the Colorado River in co-authoring the report’s chapter on high mountains. This marks the first time since 1996 that the IPCC has featured a chapter on mountains within one of its reports.

“Mountain systems provide water to people – water that is essential for drinking, growing food, industry, and energy systems. Available water depends not just on how big a glacier is or how much snow falls or how fast melting happens, but also on how the ice and snow affect plants, microbes, and soils,” said Steltzer.

Ecologist Heidi Steltzer evaluates the site of a 2018 wildfire within 10 miles of her Colorado home. Changes in snow affect the disturbance regime of U.S. mountain regions. (Credit: Joel Dyar)

The power to move mountains

The IPCC invites select scientific experts to evaluate thousands of scientific papers published each year in order to provide policymakers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation. Authors of the content on mountainous regions scoured the scientific literature for articles covering all high-mountain regions where the cryosphere is present year round or seasonally.

The SROCC adds to knowledge of glacier mass loss, thawing permafrost, and decreasing snow cover and snow duration, which affect mountain ecosystems, water supply, disturbances, and hazards. Authors of the chapter on high mountains assert that multiple hazards and risks stem from changes in the mountain environment, including impacts of variability and trends in water supply on hydropower production and implications for energy policy and water governance.

The report describes a lengthening of the growing season and more plant growth in some regions, such as the Qinghai-Tibet Plateau, due to shorter duration of snow cover. Yet, in other regions, such as the U.S. Rocky Mountains where Steltzer and the Berkeley Lab Watershed Function team are working, plants aren’t growing more even though the growing season is longer.

Susan Hubbard is lead of the DOE Watershed Function SFA project and Associate Laboratory Director for the Earth & Environmental Sciences Area at Berkeley Lab. According to Hubbard, “The multidisciplinary approach of the Watershed Function SFA aims to understand how disturbances such as earlier snowmelt influence interactions between bedrock, soil, microbes, and vegetation across changes in elevation and gradients and how this in turn affects downstream water supply and water quality.”

“Heidi’s expertise in mountain ecology is invaluable to this project, as is her understanding about how different mountainous watersheds across the world are responding to changing conditions.”

Filling the gaps

Recent SFA findings will help fill gaps identified in the SROCC report and serve as a resource for future IPCC reports. For example, the report explores the huge change in the amount of snowfall from year to year over the past three years across Colorado and many regions of the Western U.S. Also, during low-snow, early melt years, plant growth is increasingly synchronized across different elevations. Under climate change, the timing of plant growth is changing, which will affect water availability and nutrient retention and loss through plant interactions with microbes.

According to Eoin Brodie, Deputy Director of Climate and Ecosystem Sciences at Berkeley Lab and Watershed Function SFA project member, “The timing of snowfall and rate of snowmelt control microbial processes that appear to exert a significant control on nitrogen export from hillslopes to the river.”

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