Global Warming Increased Snowfall by 10–20%: Hokkaido University Uses AI Analysis to Demonstrate Causal Relationship in 2021 Heavy Snowfall*

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Associate Professor Tomonori Sato of Hokkaido University (Meteorology) and his research team announced on the 16th that the record-breaking heavy snowfall in Hokkaido in December 2021 was influenced by global warming, which increased the snowfall amount by 10–20%. This marks the first study to demonstrate a causal relationship between snowfall in Hokkaido and global warming.

The study employed a new analytical method combining machine learning, a form of artificial intelligence (AI) capable of analyzing vast amounts of data, and high-resolution simulations.

According to the Sapporo District Meteorological Observatory, from December 17 to 18, 2021, areas like Sapporo and Otaru experienced record-breaking heavy snowfall exceeding 50 centimeters within 24 hours. This was due to the passage of a low-pressure system and a strengthened winter weather pattern.

北海道新聞デジタル

温暖化で降雪量10～20％増　2021年道内大雪をAI解析　北大准教授ら因果関係を実証...

https://www.hokkaido-np.co.jp/article/1101496/

北海道大学の佐藤友徳准教授（気象学）らの研究グループは16日、2021年12月に道内で発生した記録的な大雪について、温暖化の進行で降雪量が10～20％増えたとする分析結果を発表した。　道内での降雪量と...

Niseko Real Estate CEO’s Perspective

“When Stink Bugs Abound, Heavy Snowfall Follows” — A Tale from Niseko

There’s a local saying in Niseko that if stink bugs are plentiful, a snowy winter is on its way. Indeed, stink bugs were abundant this year, and many wondered, “Could this mean heavy snow?” Sure enough, a once-in-a-decade cold wave struck, bringing relentless snowstorms. Years with increased stink bug populations often correlate with hot, humid summers. Such climatic conditions align with weather patterns conducive to heavy snowfalls on Japan’s Sea of Japan coast during winter.

As the 2024 winter season kicks off, Niseko is already experiencing continuous heavy snowfall. It’s shaping up to be another unforgettable “powder year.”

While the relationship between stink bugs and heavy snow remains scientifically unproven, the connection between global warming and extreme snow events is more evident. At first glance, global warming and heavy snowfall might seem contradictory, but in reality, they are closely linked. Here’s why:

1. Climate System Changes Due to Global Warming

Global warming leads to an overall rise in temperatures, but it doesn’t necessarily reduce the likelihood of heavy snow. Instead, it complicates climate systems, increasing the frequency of extreme weather events.

• Increased evaporation: Rising temperatures cause more evaporation from oceans and lakes, boosting atmospheric moisture. This additional moisture often leads to increased snowfall in colder regions.
• Changes in precipitation: In areas with low temperatures, higher moisture levels result in more snow, potentially causing heavy snowfalls.

2. The Impact of Jet Streams

Global warming accelerates the melting of Arctic ice, leading to higher temperatures in the polar region. This disrupts jet stream patterns.

• Weakened jet streams tend to meander, allowing Arctic air to push further south into mid-latitude regions like Japan or parts of North America. This can trigger record-breaking heavy snow and cold waves in these areas.

3. Regional Differences in Impact

The effects of global warming on snowfall vary by region:

• In Japan: During winter, cold air from Siberia crosses the Sea of Japan, picking up significant moisture. This often results in heavy snowfalls, especially along Japan’s Sea of Japan coast. As global warming raises sea temperatures, moisture levels increase, amplifying the risk of heavy snow.
• In North America and Europe: While warming may occasionally lead to snowstorms due to cold waves, some regions may see a long-term decline in snowfall.

4. Future Trends with Global Warming

As global warming progresses, the following trends are expected:

• Decreased frequency of heavy snowfalls: In urban and low-lying areas, rising temperatures may cause rain to replace snow.
• Increased occurrence of extreme snow events: In the early stages of warming, greater atmospheric moisture may lead to sporadic, exceptionally heavy snowfalls.

Conclusion

Global warming raises overall temperatures but also destabilizes climate systems, increasing the likelihood of extreme weather events, including heavy snow. In regions like Japan, global warming can intensify the factors that lead to heavy snowfall. Rather than being contradictory, these phenomena are interconnected, revealing the complexities of a warming planet.