Satellite data reveal the seasonal dynamics and vulnerabilities of Earth’s glaciers
Summary author: Walter Beckwith
American Association for the Advancement of Science (AAAS)
Using nearly a decade of satellite data, researchers show how glaciers worldwide speed up and slow down with the changing of the seasons – annual rhythms that reveal how Earth’s ice may respond to long-term climate warming. The findings show that glaciers in regions that reach above-freezing temperatures experience the largest seasonal swings in ice flow, and rising temperatures may amplify these movements and shift their timing worldwide. Earth’s glaciers and ice sheets have been rapidly shrinking in recent decades, and their future contribution to sea-level rise and other glacial hazards depends on the rate at which they continue to react to ongoing climate warming. However, the physical processes that govern the movement of ice are complex and incompletely understood. Investigating how glaciers respond to short-term seasonal variation in temperature and environmental conditions offers a natural laboratory for studying the ice flow dynamics. It’s well observed that glaciers worldwide show substantial seasonal swings in velocity driven by several factors. Yet despite these insights, a comprehensive quantitative understanding of the full range of seasonal glacier dynamics across regions and glacier types remains lacking.
To understand the full scope of seasonal glacier dynamics and the mechanisms that drive them, Chad Greene and Alex Gardner conducted a comprehensive global assessment of how glaciers speed up and slow down over the course of a year. Using nearly a decade of NASA satellite data – drawn from more than 36 million pairs of high-resolution images collected between 2014 and 2022 – Greene and Gardner analyzed the seasonal movement of every land glacier larger than 5 square kilometers on Earth. The approach allowed the authors to quantify how often and how strongly glaciers accelerate and decelerate throughout the year and map where ice is most sensitive to seasonal environmental forcing. According to the findings, seasonal variations in ice velocity are strongly controlled by local air temperatures. In temperate regions where annual maximum temperatures exceed 0 degrees Celsius, glaciers reach peak flow earlier in the year. The authors suggest that this occurs because surface meltwater rapidly increases water pressure beneath the glacier, reducing friction and accelerating ice movement. Moreover, the study finds that, globally, glaciers with strong seasonal variability also tended to show a weak but measurable correlation with larger year-to-year variability in flow. While this does not mean that seasonal shifts result in long-term change, it does suggest that both are influenced by glacier shape and subglacial conditions. In a Perspective, Lizz Ultee discusses the study in greater detail.
For reporters interested in topics of research integrity, author Chad Green notes, “Our results are the outcome of open data sharing and NASA policies that make satellite data public and freely available to all. Open science and the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program that funded this work maximize scientific integrity by making the scientific process fully transparent and replicable. We’re proud that anyone with a computer can download data collected by NASA for free and access our code to confirm our results.”
Journal
Science
Article Title
Seasonal dynamics of Earth’s glaciers and ice sheets
Article Publication Date
27-Nov-2025
Mountains as water towers: New research highlights warming differences between high and low elevations
image:
Bridger Mountains Friday, July 11, 2025, near Bozeman, Mont.
view moreCredit: MSU photo by Colter Peterson
BOZEMAN – In new research published this week, work by a Montana State University scientist aims to explore the gradations in elevation-dependent changes in climate, including in mountainous ecosystems like those in Montana and the Rockies.
John Knowles, an assistant professor in MSU’s Department of Land Resources and Environmental Sciences in the College of Agriculture, is one of nearly two dozen authors from around the world on the new paper, titled “Elevation-dependent climate change in mountain environments.” The work was published Nov. 25 in the journal Nature Reviews Earth & Environment.
Because they are difficult places to collect consistent data, mountain ecosystems around the world have been understudied in terms of changes in climate or long-term weather trends, Knowles said. That idea led to the research collaboration, which was led by British scientist Nick Pepin.
The new paper is a follow-up to a 2015 publication, also led by Pepin, that identified the concept of elevation-dependent warming, or EDW: the observation that changes in temperature happen fastest at higher elevations.
“Mountains are important for so many reasons,” Knowles said. “They’re sentinels of change, meaning we often detect changes first in mountain environments before lowlands.”
Mountains provide many “services,” he said, from offering ecological resources like wildlife habitat and recreation opportunities that feed mountain economies to the holding and gradual dispersion of water as snowpack melts to fill rivers and lakes.
“These research findings are important,” said Bob Peterson, head of MSU’s Department of Land Resources and Environmental Sciences. “They have direct implications for Montana towns, farms, ranches and industries, all of which need to make challenging decisions about water availability and use."
The researchers on the new paper focused on elevation-dependent variations in precipitation and surface albedo — the brightness of the landscape — in addition to updating air temperature trends over time for mountain ranges across the globe. The authors also highlight humidity, wind, aerosols and radiation as understudied components of the mountain climate system.
The brighter an environment, the more sunlight is reflected, Knowles said. The darker an environment, the more heat energy is absorbed. Snow is the brightest environmental element in the natural world, and as snowpack melts, the albedo of an area decreases, intensifying warming.
This work is particularly relevant in Montana, Knowles said, where mountain region recreation and wildlife habitat are intertwined with agricultural production and other economic engines, like the region’s ski areas.
“I like to think of mountains as nature's water towers. They accumulate and store precipitation as snow all winter long and then dispense it in nature's drip irrigation system all summer long,” he said. “In Montana, mountains are emblematic of our state. They provide the water for rivers that represent the lifeblood of our agricultural and recreation economies.”
Knowles said MSU is an ideal place to be doing his type of research. As a land-grant institution, the university’s historic and continuing contributions to agriculture and the natural sciences allow him to explore mountain ecosystems in a more comprehensive way than he could elsewhere, providing knowledge and information on the sustainability of natural and managed systems that matter to citizens of Montana.
-end-
This story is available on the Web at: http://www.montana.edu/news/24950
Journal
Nature Reviews Earth & Environment
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Elevation-dependent climate change in mountain environments
Article Publication Date
25-Nov-2025
