“Snow Monsters” – silent, twisted, mountain forests of stately conifers draped in frosty rime ice each Japanese winter – are under threat from global warming. This eerily silent, exquisitely beautiful, bizarre landscape results from a unique set of climactic conditions whose balance appears to be shifting, causing the majestic “monsters” to retreat farther up into the mountains as time goes by.
Rime With Reason
Rime is a type of ice that typically forms when tiny water droplets suspended in fog come into contact with objects on the ground whose temperatures are below the freezing point. These ice deposits can build up thick, layered coverings on mountain forests – the high elevation of the trees brings them into frequent contact with low clouds that hug the mountain slopes.
Meteorologists describe “hard rime” as occurring on the windward (wind-facing) side of tree branches or other solid objects, with ideal conditions being high wind velocities and air temperatures varying between −2 °C (28 °F) and −8 °C (18 °F).
“Soft rime”, on the other hand, forms when water droplets in mist or light freezing fog adhere to the outer surfaces of objects when the winds are mainly calm. The Snow Monsters of northern Japan display both types of rime, and lots of it!
Fog Thorns
Northern Japan presents a perfect storm, as it were, of meteorological and geological conditions that act together to facilitate the formation of winter rime. Prevailing westerly winds drive moisture-laden air from the Sea of Okhotsk inland, where it’s forced upwards against heavily forested mountainsides. Moisture condenses out of the air as snow and as rime.
Rime accumulations on conifer trees can grow to astonishing thicknesses but usually the trees can support the weight. This is partly due to rime formation being a gradual process. In addition, the affected trees have been blanketed with rime since they first sprouted – their summer shapes owe much to “sculpting” by annual rime formations. One might say these trees are Mother Nature’s bonsai.
Though rime-encrusted Snow Monsters occur at a number of locations in northern Japan, some of the largest and best-known gatherings can be found in the Hakkōda Mountains of Aomori prefecture, along the slopes of Mount Moriyoshi in Akita prefecture, and at the Zao ski resort in Yamagata prefecture.
Skiing and hiking amidst the Snow Monsters is a surreal experience to say the least, especially when they’re illuminated at night with multicolored spotlights! Here’s a short video showing just the thing, though the Snow Monsters weren’t at their most monstrous level of snowiness that year:
Zao ski resort was the focus of an investigation by a team from Yamagata University, the results of which have disturbed and even alarmed scientists monitoring the ever-increasing signs of global warming.
Melting Monsters Of Mount Jizo
Investigators led by Yamagata University geochemistry professor Fumitaka Yanagisawa recently made observations and took measurements of the many ice-covered trees found around the Jizo-Sancho ropeway station 1,661 meters (5,450 ft) above sea level.
The measurements were compared with those taken at the local meteorological observatory. The station was established in 1914 shortly after the mountain’s extensive ranks of Snow Monsters were first noted by outside observers visiting the Zao hot spring resort near 1,736 meter (5,695 ft) high Mount Jizo.
Snow Monsters on Mount Jizo occur today at altitudes higher than 1,550 meters, or 5,085 feet. An examination of the weather station’s records, however, revealed that nearly a century ago the frozen manifestations extended down to 1,400 meters or 4,595 feet above sea level. As the years progressed, the “starting line” for Snow Monster sightings has inexorably shifted higher up the mountain’s slopes.
Temperature measurements on the mountain tell a similar story, as average January temperatures in the area have risen by 2.38 degrees Celsius over the past 80-odd years. To put things in perspective, the average January temperature from 1926 through 1930 was minus 2.16 degrees Celsius. Over the past four years (2008 through 2011), the average January temperature at the Mount Jizo weather station had risen to 0.22 degrees Celsius.
According to professor Yanagisawa, if temperatures in the region continue to rise at the current rate, “trees will only freeze at an altitude of 1,700 meters (5,575 ft) or higher after three to four decades, in theory.” Yanagisawa points out. The problem is, trees don’t grow at altitudes over 1,700 meters on Mount Jizo. No trees, no Snow Monsters. In effect, the immovable abominable snowmen will have become extinct.
Snow Time Like The Present
Sadly, what happens on Mount Jizo doesn’t stay on Mount Jizo. Global warming skeptics shouldn’t be fooled by the fact that during the winter of 2010-11, Yamagata experienced the heaviest snowfalls in the past five years and January’s average temperature registered minus 1.6 degrees Celsius. Snow Monsters followed the chilly air down the mountainside and could once again found at altitudes as low as 1,500 meters (4,920 ft).
Not so fast: “Temperatures fluctuate, but they are rising gradually,” warns professor Yanagisawa, who reminds us that long-term climate trends need to be respected and “the average temperature has risen over the past five years.”
Based on the overall trends noted since 1914, experts are predicting that assuming temperatures continue to rise at current levels, conditions by 2050 will no longer support the growth of Snow Monsters on Mount Jizo – and likely elsewhere as well. A chilling forecast indeed.



