My attention was drawn to the Himalayas this past week. It was the peak of mountain climbing season, and powerful Cyclone Fani was approaching the region. I wrote in Forbes about my concerns that Fani could cause snow, wind, and avalanche problems for climbers if a certain track was taken, my colleague Professor Tom Gill alerted me of something else. Gill, a professor of geological sciences at University of Texas-El Paso, was focused on another hazard. Gill said, "If and when storms like the massive tropical cyclone (Fani) currently hitting India now slam into the Himalayas, it will increase glacial melt and runoff and heighten the risk for these types of lake outbursts and floods." What are these outburst floods, and why are scientists concerned?
I will circle back to answer that question after I establish a few geologic and geographic facts. The 3rd tallest mountain in the world is called Kanchenjunga Massif. Its peak elevation is 28,169 feet (8,586 meters, and it is situated near the border of India (Sikkim state) and Nepal. It is found within the Great Himalaya Range along with its record-breaking family members, Mt. Everest (1st) and K2 -Chhogori (2nd). As a reference point, it is located about 75 miles (120 kilometers) to the southeast of Mt. Everest.
In April 2019, NASA released stunning satellite images of a glacial lake that sits at the foot of the mountain. Using images from the Landsat 5 and Landsat 8 satellites respectively, scientists determined that the lake doubled its size (graphic above) in just three decades. Mauri Pelto is a glaciologist at Nichols College. He told NASA:
This lake growth is not unusual at all in recent decades in the area....Just in that little tiny region, there have been a dozens of new lakes filling formerly glacier filled valleys and fed from melting glaciers.
In 1988, the lake, which is found in the Sikkim province of India, was 2600 feet (800 meters). In 2017, the lake was measured at roughly 5200 feet (1600 meters).
Glacial lakes are formed when a mountain glacier forms, expands, and then melts. I had the opportunity to witness a spectacular glacial lake with my own eyes on a recent family trip to Glacier National Park in Montana. According to NASA's Earth Observatory website,
Around the world, mountain glaciers are retreating due to rising snowlines: warmer air is rising to higher elevations, promoting more melting and less snow accumulation. (In some places, it also means more rain.) That has been the consistent observation around the world’s tallest and coldest mountains over the past few decades.
This is precisely why Pelto says such activities are not unusual in recent decades. He also points out that other glacial lakes in the Himalayas have experienced rapid growth as well. The trends from the NASA press release tell the story:
- A 500-meter long lake formed by 2012 from the Changsang Glacier, which is located north of the same mountain.
- The retreating Lhonak Glacier fed a lake which has expanded by 1,900 meters from 1962 to 2008.
- 85 new glacial lakes formed during the period 2003 to 2010 in the Sikkim Himalaya region along.
Professor Gill's concern about future cyclones and extreme activity is rooted in his knowledge of "glacial lake outburst floods." The lake at Kokthang is likely not going to experience this because of a prominent barrier ridge. However, other glacial lakes in this region and elsewhere around the world are vulnerable to these sudden runoff events whereby water breaks through soil, sediment and rocks. Nearby mountain communities are at risk, and an extreme precipitation event like a Cyclone can amplify the situation quickly.
When I visited Glacier National Park, I explained to my kids the reason that it was so urgent that we visit the park. I shared this Tweet from the National Park Service with them:
In 1910, the park had over 100 glaciers but by 1966 only 35 remained. Today, rising temperatures are shrinking every glacier in the park. In 2015, 26 met the size criteria to be designated active glaciers.
For us, it was a matter of seeing a glacier while we could. For mountain communities vulnerable to glacial lake outburst floods, it could be a matter of life and death.
