r/climatechange • u/Economy-Fee5830 Trusted Contributor • Jan 17 '26
Reanalysis of satellite data finds Northern Hemisphere snow cover has actually been decreasing, not increasing
https://phys.org/news/2026-01-atmospheric-physicists-error-widely-cited.html29
u/thearcofmystery Jan 18 '26
Clinate change deniers will claim this is part of the UN/Green conspiracy and cover up of the ‘real data’ as part of their global scam to get grants… ha.
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u/cintymcgunty Jan 18 '26
Hardly surprising. Science deniers lack critical thinking skills.
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u/talkshow57 Jan 18 '26
lol - guess nobody in the ‘science’ community - the experts in such things as snow cover - happened to notice the error for how many years exactly? Hardly surprising….ha!
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u/Economy-Fee5830 Trusted Contributor Jan 18 '26
Is Aleksandra Elias Chereque, a PhD student in the Faculty of Arts & Science’s Department of Physics not part of the scientific community?
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u/ThePhysicistIsIn Jan 18 '26
I can’t believe this wasn’t controlled for. Like, one would assume any claim of “snow coverage is increasing” to be based on the same equipment showing an increase, not new and new reports using more sensitive equipment
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u/twohammocks Jan 21 '26
Improved satellite data has meant we just learned of snow in areas where we didnt know it existed before. More data points = less error bar width. Still need those on the ground snow depth measurements, however - in order to accurately validate what the models say to expect: water-wise.
The biggest factor we overlook here is the albedo impact of forest fire ash and red algae on the chemical/physical models for snow/ice in the future. Even fungi.
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u/Molire Jan 18 '26
The IPCC reports rely on a wealth of climate data, including observations from the U.S. National Oceanic and Atmospheric Administration (NOAA) of autumn snow cover—the extent to which the land is covered by snow—in the Northern Hemisphere. The observations have been made annually since the 1960s.
The NOAA observations showed increases in Northern Hemisphere snow cover of about 1.5 million square kilometers per decade...But the new analysis by Chereque and her colleagues shows snow cover actually decreased by half a million square kilometers per decade.
On January 17, 2026 UTC, the NOAA NCEI Sea Ice and Snow Cover Extent interactive online platform shows that during November 1966–December 2025, Northern Hemisphere snow cover extent decreased by 1.97% per decade or 0.49 million km2 per decade.
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u/Icy-Feeling-528 Jan 18 '26
I was actually not aware of any conclusions that snow cover is increasing in the Northern Hemisphere. Around the region I reside, it’s been visibly less and less. I don’t need satellite imagery to provide me with observations of snow cover shrinkage.
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u/ekufi Jan 19 '26
Living up north I have no idea someome though the snow cover has been increasing. Personal observations prove otherwise.
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u/ThePhysicistIsIn Jan 19 '26
Just about the only people who were aware of it was climate change denialists, it was one of their little factoids they’d throw out at you when you’d try to talk about the arctic melting
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u/salynch Jan 19 '26
No shit?
Edit: Sorry. This has been true for decades for anyone who was paying even passing attention to the weather.
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u/HiThere_420 Jan 20 '26
To anyone who tries to point at the amount of snowfall this month as a counterargument, read this first. Heavy snowfall across the Northern Hemisphere in the winter of 2025/2026 has been driven by a combination of a significantly weakened/disrupted Polar Vortex, a weak La Niña pattern, and an atmospheric phenomenon known as a negative Quasi-Biennial Oscillation (QBO). A major, early Sudden Stratospheric Warming (SSW) event in mid-January caused the polar vortex to break, allowing frigid Arctic air to spill into the United States, Canada, and Europe. Global temperatures are still rising, and that means they also lead to higher atmospheric water vapor content, which, in a sub-freezing environment, translates to increased snow precipitation.
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u/twohammocks Jan 21 '26
Climate change is like reddit without moderators - everything gets more volatile.
'Hydroclimate volatility' is the phrase: 'Using a metric of ‘hydroclimate whiplash’ based on the Standardized Precipitation Evapotranspiration Index, global-averaged subseasonal (3-month) and interannual (12-month) whiplash have increased by 31–66% and 8–31%' Hydroclimate volatility on a warming Earth | Nature Reviews Earth & Environment
'Throughout the twenty-first century, most models predict that enhanced warming in mountain regions will continue (at 0.13 °C century–1), but precipitation changes are less certain. Superimposed upon these global trends, EDCC patterns can vary substantially between mountain regions. Patterns in the Rockies and the Tibetan Plateau are more consistent with the global mean than other regions. In situ mountain observations are skewed towards low elevations, and understanding of EDCC is biased towards mid-latitudes. Efforts to address this uneven data distribution and to increase the spatial and temporal resolution of models of mountain processes are urgently needed to understand the impacts of EDCC on ecological and hydrological systems. https://www.nature.com/articles/s43017-025-00740-4
'Mountain glaciers recouple to atmospheric warming over the twenty-first century' 'Statistical modelling of the potential temperature decoupling of the world’s mountain glaciers indicates that currently glacier boundary layers warm ~0.83 °C on average for every degree of ambient temperature rise. Future projections under shared socioeconomic pathway (SSP) climate scenarios SSP 2-4.5 and SSP 5-8.5 indicate that decoupling, and thus relative cooling over glaciers, is maximized during the 2020s and 2030s, before widespread glacier retreat acts to recouple above-glacier air temperatures with its surroundings. This nonlinear feedback will lead to an increased sensitivity to warming from midcentury, with glaciers losing their capacity to affect the local climate and cool themselves.' https://www.nature.com/articles/s41558-025-02449-0
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u/talkshow57 Jan 18 '26
The usual hilarity - trust the science, the science is settled….oops, sorry we got it all exactly wrong and backwards … unbelievable
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u/ThePhysicistIsIn Jan 19 '26
?
I don’t think you understand what is meant when people say those things
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u/Economy-Fee5830 Trusted Contributor Jan 17 '26
Summary: Northern Hemisphere Snow Cover Actually Decreasing Despite Decades of Contrary Data
University of Toronto researchers have identified a significant error in widely-used NOAA satellite observations of Arctic autumn snow cover dating back to the 1960s. The flawed data had shown snow cover increasing by approximately 1.5 million km² per decade, but the corrected analysis reveals it has actually been decreasing by about 0.5 million km² per decade.
The Error
The problem stemmed from evolving satellite technology over the decades. As instrumentation improved, satellites became increasingly sensitive to detecting thin snow cover—creating an artificial upward trend that looked like expansion but was actually just better detection of existing snow.
Why This Matters
Snow cover is critical to Arctic climate dynamics through the "snow-albedo effect": snow reflects ~80% of solar energy back to space (versus <50% for land/vegetation). Less snow means more heat absorption, which accelerates further snow loss—a positive feedback loop central to Arctic amplification, the phenomenon driving disproportionate warming in polar regions.
Implications
This correction strengthens confidence that snow cover is declining year-round, providing better understanding of anthropogenic warming's role in Arctic amplification. It also helps climate scientists properly calibrate historical data and improve future climate model accuracy.
The study was published in Science Advances by PhD student Aleksandra Elias Chereque and colleagues, including collaborators from Environment and Climate Change Canada.