The world is home to natural spectacles so surreal they seem plucked from fantasy. Among winter's most breathtaking displays are Japan's eerie 'juhyo', or snow monsters, on Mount Zao. These ghostly, frozen figures draw thousands of visitors each year. However, this iconic phenomenon is now facing a silent crisis, threatened by the dual forces of climate change and forest pests, endangering a symbol of Japan's wilderness and a cornerstone of local tourism.
What Are Japan's Snow Monsters?
Japan's 'juhyo' are far from ordinary snow-laden trees. They are a rare natural sculpture formed under specific conditions. When persistent, strong westerly winds blow supercooled water droplets from the Sea of Japan, these droplets instantly freeze upon hitting the evergreen Aomori todomatsu fir trees on Mount Zao's summit. This process, called rime ice accumulation, builds thick, fantastical layers of frost. The ice forms distinct shapes resembling 'shrimp tails', which cluster together to create the towering, monster-like figures that make the landscape between Yamagata and Miyagi prefectures so unique.
As Emeritus Professor Fumitaka Yanagisawa explained to the BBC, "Because such precise meteorological and ecological conditions align in very few places, Zao's snow monsters are a phenomenon almost unique to northern Japan." This rarity is what makes their decline so alarming.
The Alarming Shrinkage of a Winter Icon
Recent research led by Professor Yanagisawa has uncovered a disturbing trend: the snow monsters are getting smaller. By analysing summit photographs dating back to 1933, the research team tracked a dramatic reduction in size. In the 1930s, these icy sentinels stood impressively at 16-20 feet tall. This size decreased to 7-10 feet in the postwar decades. Shockingly, since 2019, many juhyo now measure a mere 1.6 feet or less.
Scientists point to two primary culprits for this decline:
- Rising Winter Temperatures: Warmer conditions disrupt the formation of the necessary supercooled droplets and rime ice.
- Damaged Fir Forests: The host Aomori todomatsu trees have been severely weakened. A devastating moth infestation in 2013 stripped the trees of their needles. This was followed by bark beetles attacking the already vulnerable trunks. Yamagata officials report around 23,000 fir tree deaths, accounting for roughly one-fifth of the prefecture's fir stands.
Race Against Time: Conservation and Revival Efforts
Recognising the urgent threat, Yamagata Prefecture launched the Juhyo Revival Conference in March 2023. This initiative brings together researchers, local residents, and business owners to strategize the protection of Mount Zao's iconic winter figures. Practical conservation work is already underway. Since 2019, the local forest office has transplanted over 190 naturally regenerated saplings to the summit areas. However, patience is key, as these firs take 50 to 70 years to reach full maturity.
Local students are also joining the fight. Pupils at Murayama Technical High School are actively cultivating seedlings and experimenting with regeneration techniques, facing challenges like field mice damaging young shoots. For the community, the stakes are high. "If the juhyo disappear, it would be a huge blow," Genji Akiba of the Zao Onsen Tourism Association told the BBC. The snow monsters attract tens of thousands of visitors annually, forming a vital pillar for the local economy.
The battle to save the juhyo is a long-term commitment. Conservationists emphasise the need for patience and sustained effort across generations. For students and locals alike, these snow monsters represent a precious natural legacy—a rare wonder of Japan they are determined to preserve and pass on to the future.
