![\\"logo\\"](\\"/img/logo-dpa-factchecking.svg\\"/) *About ![\\"IFCN](\\"/img/ifcn-certificate.png\\"/) ![\\"EFCSN](\\"/img/efcsn- certificate.png\\"/) ## Fallacious reasoning # Less and less snow in the northern hemisphere Published on 22.3.2023, 14:14 (CET), updated on 22.3.2023, 15:02 (CET) In winter, the snow cover in the northern hemisphere still seems as more extensive than 50 years ago. However, the snowy season tends to decrease under the effect of global warming. Many Internet users claim, on Facebook and Twitter in particular, that “ the extent of snow in the northern hemisphere" is almost identical to that which prevailed 50 years ago. According to these publications, the increase in emissions of carbon dioxide (CO2) in the atmosphere - the main cause of climate change - wouldn\'t change anything. The snow would still fall abundance in this part of the globe. But is this allegation correct? ? ## Assessment This statement is false. As two climatologists explain to the dpa, trends observed over several decades show that the coat snow tends to decline in the northern hemisphere. This phenomenon, described in several studies and summarized in the Group's sixth evaluation report of intergovernmental experts on climate change (IPCC), is observed more particularly in spring. Alongside the snow cover, the mass snowfall also tends to decrease. ## Facts The publications relaying this false information are based on two images from the Global snow lab at Rutgers University, in the United States, specializing in the study of snow cover on a global level. On the first of them, we can see that in January 2023 no less than 46.27 million km2 were covered with snow in the northern hemisphere. The second shows the extent of snow 50 years earlier: we see that in January 1973, this covered a comparable area of ​​46.25 million of km2 in the same part of the globe. But can we, on the basis of this simple observation, call into question the global warming? As climatologist from the University of Liège Sébastien explains to the dpa Doutreloup, “in climatology, it is necessary to study trends over several decades, otherwise the analysis is biased by the climate's own variability. In other words, we cannot compare two meteorological phenomena punctual (such as snow cover measured during two months of January, For example). “A real analysis must take into account every month between year X and Y to see the real trend,” he explains. Concerning snow cover in the northern hemisphere, "observations show a decrease over the last decades in spring (April) », underlines the climatologist Hugues Goossens of the Catholic University of Leuven. “Changes in snow cover are less clear in the heart of winter. Despite global warming, January remains a very cold month and therefore the presence of snow is possible in many regions. However, in April, warming pushed many regions towards temperatures more often positive, which prevent the snow from holding for a long time on the ground, hence the clearer trend for this month (and the trend towards shorter periods of snow cover),” he adds. These observations can be found in particular on the website dedicated to climate information from the American Ocean Observing Agency and atmospheric (NOAA). The IPCC also mentions this in its sixth assessment report, published in 2021. The group of experts affirms with a “high degree of certainty" that the snow cover tends to decrease in the northern hemisphere, particularly in spring. Extent does not equal quantity Comparing only snow cover, posts shared on social networks also sow doubt about the quantity. “What is analyzed here is the extent of the snow cover, this does not say absolutely nothing on quantity,” notes climatologist Sébastien Doutreloup. Because although the snow level can vary greatly from one year to the next due to climate fluctuations, the mass of snow also tends to decline in the northern hemisphere, he adds. This is notably demonstrated in this study, published in the scientific journal The Cryosphere, in 2020. When snow cover occasionally increases during certain periods or in some regions, "it is simply because the atmosphere is more hot (because of global warming). Therefore, she can accommodate more humidity and therefore potentially more precipitation snowy if the air temperature is equal to or lower than 0°C. But even if the winter temperature warms up significantly in the northern hemisphere, it has not yet passed the 0°C mark everywhere. We can therefore still locally have a larger extent of snow than in the past, even if this snow is less thick and lasts less long,” explains Sébastien Doutreloup. Simplistic and fallacious reasoning False information fueling doubt about climate change are legion on social networks. They often aim to discredit scientifically validated results through simplistic and fallacious reasoning. Their authors generally use the same process. By comparing phenomena occasional meteorological events, they establish an erroneous link between them, without take into account climatic changes observed over the long term. This recurring strategy has already been the subject of several verifications, including one from AFP also on snow cover (here) and the other from the dpa on the area of ​​the Arctic sea ice (in Dutch, here). Note: A faulty link was later replaced (Situation as of 03.22.2023) ## Links Facebook post (archived version) Twitter post (archived version) Global slow lab at Rutgers University (archived version) Original illustration January 2023 (archived version) Original illustration January 1973 (archived version) About climatologist Sébastien Doutreloup (archived version) About snow cover in the northern hemisphere (archived version) IPCC Sixth Assessment Report (archived version) IPCC website (archived version) Snow mass study (archived version) AFP-Factual fact-check (archived version) dpa fact check ### About dpa fact checks This fact check was written as part of the independent program of Facebook/Meta check. More information about this program can be found here. To learn more about how Facebook/Meta manages accounts that spread misinformation, click here. 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Snow cover in the northern hemisphere is almost identical despite 50 years of CO2 emissions