Zao's famed trees' future not frosty

YAMAGATA (Kyodo) Researchers warned Thursday that in 20 years, the popular frosted, snow-sculpted trees in the mountain resort of Zao, Yamagata Prefecture, will be only a memory due to global warming.

Tourists walk among the "ice monsters," created when frost and snow envelop trees, at the Zao mountain resort in February. KYODO PHOTO

The snowed-over trees can now only be seen for two months, almost half the duration of 30 years ago.

"We fear the average temperature may rise by a further 2 degrees in 20 years at the earliest and that hoarfrost may not form on trees in Zao," said Fumitaka Yanagisawa, associate professor of environmental chemistry at Yamagata University. "Urgent measures are needed against warming."

The group has been sampling frost and ice at an elevation of 1,660 meters, near the summit of Mount Jizo in Yamagata Prefecture, every year since 1994 to check the impact of acid from air pollution on frost forming on trees. They also used similar data from the 1970s collected by the late Masajiro Abe, who was also a professor at the university.

The group said trees encased in frost and snow were observed for nearly four months, from mid-December to early April, a year in the 1970s but since 2000, the phenomena lasts for just two months, from early January to early March.

Yanagisawa said the rapid pace of global warming is responsible, noting that the average temperature in city of Yamagata, which encompasses the Zao peaks, has risen by around 2 in the past 100 years -- and by around 1 in the last 30 years alone.

The group also said the area where frost- and snow-covered trees can be seen has gotten smaller in the past decades. People could see them at an elevation of around 1,450 meters in the 1970s but they have had to climb to around 1,550 meters since 2000. This year, which has seen a warm winter, they can only be seen at around 1,600 meters.