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A recent snow covers the ground and tree limbs in New York City's Central Park. A study led by Mississippi State University researchers examined regional snow cover trends across the Northern Hemisphere. The results suggest shrinking snow coverage and seasonal shifts in when the wintry layer comes and goes. Credit: Mary Pollitz
Faculty at Mississippi State University are continuing work at the intersection of mathematics, statistics, and climate science with the publication of a new study examining regional snow cover trends across the Northern Hemisphere. The results suggest shrinking snow coverage as well as seasonal shifts for when the wintry layer comes and goes. The study, "Regional Analysis of Snow Presence Trends in the Northern Hemisphere," was published in January in the Journal of Hydrometeorology.
Led by Jonathan Woody, associate professor in MSU's Department of Mathematics and Statistics, and Jamie Dyer, dean of the College of Integrative Studies and professor of meteorology and climatology in the Department of Geosciences, the researchers examined satellite data to determine whether snow cover across the Northern Hemisphere is increasing or decreasing, and where those changes are occurring. After removing unreliable data, they found that significantly more areas are losing snow cover than gaining it.
The research builds on the team's widely cited 2023 study that introduced a statistical framework for evaluating long-term snow cover trends.
"We studied a new high-resolution Rutgers University Global Snow Lab Northern Hemisphere Weekly Snow Cover Extent Data Record. Using a two-state Markov chain model with periodic dynamics to analyze snow cover across the Northern Hemisphere, we can see how trends vary both geographically and seasonally," Woody said.
Dyer emphasized the importance of interdisciplinary collaboration in producing robust climate science.
"Climate datasets are inherently complex," Dyer said. "By combining statistical expertise with climate science expertise, we ensure that trends are not artifacts of data bias or methodology."
The 2026 research co-authors include JiaJie Kong of the University of California at Berkeley and Penelope Prochnow, a recent MSU graduate with a bachelor's degree in Data Science from MSU's Data Science Academic Institute who contributed substantially to the research and now works as a data scientist in Huntsville, Alabama.
The team's research reveals about 24% of regions analyzed show declines in snow-covered areas compared to about 9% showing increases, with a noticeable seasonal shift. While observed snow cover has slightly increased in late summer and early fall in some areas, it is clearly declining beginning in March, suggesting earlier spring melt. The strongest overall declines occur in Europe and central Asia, while parts of central Canada and the northern Great Plains show increases. Additionally, the southern edge of seasonal snow cover is retreating in many areas, indicating a general shift toward less persistent snow across much of the hemisphere.
In 2023, Woody and Dyer published research in the Journal of Hydrometeorology that was described as the first statistically rigorous, hemispheric-scale assessment of snow presence trends using satellite data collected between 1967 and 2021 and gridded by the National Oceanic and Atmospheric Administration.
More information Jonathan Woody et al, Regional Analysis of Snow Presence Trends in the Northern Hemisphere, Journal of Hydrometeorology (2026). DOI: 10.1175/jhm-d-25-0061.1
— Source: Phys.org (https://phys.org/news/2026-03-northern-hemisphere-analysis-tracks-fast.html)
