A severe cold wave is descending on Japan this week. On the other hand, global warming is causing the melting of ice sheets and glaciers around the world.

A paper published in Nature on January 18 showed that temperatures on the Greenland ice sheet in recent years are 1.5°C higher than in the 20th century, indicating that the impact of anthropogenic warming has reached the central and northern parts of Greenland, accelerating massive ice sheet melting.　

A paper published in Science in early January also warned that glaciers in mountainous regions, excluding Greenland and the Antarctic ice sheets, are facing a warming-related crisis. The 2.7°C temperature rise projected under the commitments of countries at COP26 is expected to result in widespread glacier melting in mid-latitude regions by 2100. This could contribute to sea level rise.

Not only glaciers, but also snow cover reduction has been reported. A recent paper in Nature observed that over the past 50 years, the duration of snow cover in the Alps has decreased by 5.6% per decade. Using dendroclimatology, a method that analyzes the annual rings of common juniper trees in areas 2,000 meters above sea level, the authors report that the current snow cover period is 36 days shorter than the long-term average and that the Alps is facing a decrease in snow cover that has not been experienced in the past 60 years.

The editorial in Science points out that the melting of mountain glaciers, although on a smaller scale than the Greenland and Antarctic ice sheets, which could bring about a tipping point with massive changes that would gradually become irreversible, support the livelihoods of those who depend on them for their water supply. The loss of these sources would result in the loss of water sources for millions of people and increase the risk of sudden floods and landslides, and the need for action to curb global warming will be emphasized.

Contributor: IIYAMA Miyuki (Information Program)