Impact of Rising Temperatures on Mountain Ranges
According to a new UNESCO report, soaring temperatures are causing rapid and largely irreversible changes in mountain ranges globally. Higher elevations are warming faster, glaciers are melting, permafrost is thawing, snow cover is declining, and snowfall patterns are becoming erratic.
Glacier Melting
- Glaciers have lost over 9,000 billion tonnes of mass since 1975, equivalent to an ice block the size of Germany with a thickness of 25 meters.
- The last three-year period recorded the largest glacial mass loss on record, with 450 gigatons of mass loss in 2024 alone.
- Factors contributing to glacier melting include increased wildfires and dust storms, depositing black carbon and other particulate matter on glaciers, enhancing solar radiation absorption and melt rates.
Accelerating Permafrost Thaw
- Permafrost, ground frozen for at least two years, is rapidly melting, releasing organic carbon into the atmosphere, exacerbating climate change.
- Mountain permafrost contains approximately 4.5% of global soil organic carbon.
- Permafrost stabilizes rock slopes and debris-covered areas; its melting increases erosion and landslide risks.
Decline in Snow Cover
- There is a significant decline in snow cover, especially in spring and summer, with a global mean decline of 7.79% between 1979 and 2022.
Erratic Snowfall Patterns
- Atmospheric warming is shifting the elevation at which rainfall transitions to snowfall, reducing snow cover depth and duration at lower elevations.
- Increased fraction of precipitation falls as rain instead of snow, leading to shorter snow duration and earlier snowmelt.
Significance of Mountain Changes
Mountains cover 33 million sq km of Earth's surface and are crucial for sustaining life. Around 2 billion people depend on mountain freshwater resources, and continued climate-induced glacier melting can have catastrophic impacts. Changes in water flows, increased erosion, sediment loads, and GLOFs impact water resources downstream.
Glacial Lake Outburst Floods (GLOFs)
- Caused by the failure of natural dams containing glacial lakes, GLOFs have resulted in over 12,000 deaths in the past 200 years and severe infrastructure damage.
Contribution to Sea Level Rise
- Melted glacier ice accounts for 25 to 30% of the observed increase in global sea levels.
- Between 2006 and 2016, glacier ice mass loss amounted to 335 billion tonnes per year, leading to nearly 1 mm annual sea level rise.
- Each millimeter rise in sea level can expose up to 300,000 people to annual flooding.
Sulagna Mishra, a scientific officer at the World Meteorological Organization, highlights the urgent need for awareness, policy changes, and resource mobilization to mitigate these impacts.