As the climate warms, glaciers bear the brunt. According to a “comparison map of global temperature in 2021 and the average value of 1951-1980” released by NASA, it can be seen that the temperature in the polar regions, Greenland, and my country’s Qinghai-Tibet and other alpine regions has a large temperature change. These are the areas where glaciers are widespread.
A “Glacier” Funeral
The Ok Glacier, located in Reykjavik, the capital of Iceland, was formed about 700 years ago, but in just over a hundred years, the area has been reduced from 16 square kilometers to less than 0.7 square kilometers. It was officially declared in 2014 “Dead”, becoming the first glacier to be declared dead. On August 18, 2019, major Icelandic officials and scientists went to the original site of the glacier to hold a “funeral” for the glacier. Its tombstone is engraved with “a letter to the future”, calling for global attention to the impact of climate warming on glaciers.
In China, the problem of melting glaciers is equally serious. The “Second Glacier Catalogue in China” released in 2014 shows that there are 48,571 glaciers in China with an area of more than 0.01 square kilometers, with a total area of 51,766 square kilometers. However, in the past 30 years, the number of glaciers in China has decreased by about 20%. .
On the earth, 85% of the fresh water resources that human beings rely on are stored in glaciers. Melting glaciers will also greatly affect hydrological conditions and the ecological environment. At the same time, the melting of glaciers will also increase the instability of glaciers, which will lead to a series of disasters.
Sea level rise 20 cm in 40 years
According to NASA data, the current global sea level has risen by 20 cm compared to 1870, and the rate of sea level rise is also accelerating, from 2.5 mm/year in the 1990s to the current 3.4 mm/year. According to a report published by the Antarctic Scientific Research Council (SCAR), the melting of glaciers in West Antarctica is accelerating. It is estimated that by 2100, the global sea level will rise by 1.4 meters, and more than 10% of the world’s population will lose the land on which they live.
Ice avalanches occur frequently
Ice avalanche refers to the rapid toppling, sliding and falling of large ice bodies or even the entire glacier along the internal fracture surface or fragile surface of the glacier on a slope with a large slope. It is the most violent glacier. disaster form. Historically, ice avalanche disasters have occurred many times, but usually on a small scale and with low frequency. However, in recent years, ice avalanche disasters have occurred frequently and on a large scale, and the causes are closely related to climate warming. On the one hand, the melting of glaciers itself will increase the instability of the ice body. On the other hand, the meltwater entering the cracks will also exert pressure on the ice body and play a lubricating role, greatly increasing the risk of collapse.
On July 17, 2016, Glacier No. 53 of the Glacier Group in the Aruco Lake District of the Ngari Region of the Qinghai-Tibet Plateau broke from an altitude of about 5,800 meters, with a cross-section width of 2.4 kilometers and a fan length of 5.7 kilometers. Covering 9.4 square kilometers, 9 people were killed. Two months later, glacier No. 50 on the south side also suffered an ice avalanche. Such a large-scale ice avalanche occurred in the northwest of the Qinghai-Tibet Plateau where glacial activity has been relatively stable. It is really rare and has aroused great repercussions at home and abroad.
Ice avalanche triggers secondary disasters
On February 7, 2021, a glacier collapsed in the Chamori area of Uttarakhand, India, triggering large-scale flooding of the Alleghenda and Duli Gang rivers, destroying residential houses and two hydropower projects along the banks, causing thousands of deaths in the surrounding areas. People were forced to evacuate urgently, and more than 200 people died or disappeared.
On July 3, 2022, an alpine glacier in the Marmolada mountain range (Marmolada) in northern Italy also collapsed. After the ice cap on the top of the mountain collapsed, it was mixed with rocks and poured down the mountain at an altitude of more than 3,300 meters, killing 11 people , 8 people were injured.
If the glacier occurs at a higher altitude, it can further induce secondary disasters such as moraine debris flow, glacier debris flow, and glacier lake collapse.
Glacier surge cannot be ignored
Glaciers are not static, but under the influence of gravity or the deformation of the underlying bedrock, they are moving slowly at all times, with speeds ranging from a few meters to hundreds of meters per year. The glacier jump is a special phenomenon of glacier movement. It means that the glacier advances at a speed dozens or even hundreds of times higher than the normal movement speed within a few days or tens of days. It is a manifestation of glacier instability. form.
Glacier jumping, one type is under the cold climate, caused by the increase of subglacial pressure and melting and lubricating the glacier; The pressure rises and the lubrication pulsates. The pulsating glaciers will flood pastures, farmland, houses, and cause damage to infrastructure.
Glacial lake burst causing floods
Glacier lakes are natural water bodies formed by melting water from modern glaciers or accumulating water in moraine ridge depressions, including glacier terminal lakes, glacier surface lakes, and glacier recharge lakes.
Glacial lake outburst floods refer to sudden floods caused by the collapse of glacial lake dams and massive drainage. There are many reasons for the collapse of the glacial lake dam, such as glacier movement, flowing water erosion, water pressure exceeding the bearing capacity of the dam body, rock and ice collapse, and earthquakes, all of which will lead to the collapse of the glacial lake. The warming of the climate and the melting of ice caused by high temperature weather have also become one of the important reasons for the collapse of glacial lakes in recent years.
The Qinghai-Tibet Plateau in my country is a high-incidence area for glacial lake outbursts, where the terrain is high, the climate is cold, and glaciers are widespread. The melting water of glaciers converges into rivers, making this place the birthplace of several major rivers such as the Yangtze River and the Yellow River. Therefore, it is known as the “Water Tower of Asia”, and the melting water also converges into many ice lakes. According to statistics by some scholars, glacial lake outburst floods occur frequently in the Tianshan Mountains, Karakoram Mountains, Himalayas, Nyainqentanglha Mountains, and Hengduan Mountains, among which the Himalayas are the most frequent. Since the 1980s, there have been an average of 1.3 collapse events per year in the Himalayas and Nyainqentanglha Mountains. Ice avalanches, glacial slides, and upstream water are the main reasons for the collapse of glacial lakes, and these are inseparable from climate warming.
Glacial lake outburst floods are sudden and often cause catastrophic erosion and damage to the downstream. For example, on July 5, 2013, Ranri A Co in Jiali County, Tibet Autonomous Region collapsed, 49 houses were destroyed, a large number of farmlands and bridges were damaged, and the direct economic loss was as high as 270 million yuan.
Glacial mudslides are destructive
Glacier debris flow refers to the sediment flow formed by glacier floods and glaciers or other frozen weathered sediments in the alpine glacier environment. It is sudden, fast (up to 200km/h), and long spread over tens of kilometers), large-scale (volume up to one million cubic meters) features. Like general debris flow, its occurrence also requires energy (steep terrain provides gravitational potential energy), material source (rich loose accumulations such as moraines, ice water sediments) and water source (ice and snow melt water or glacier lake outburst floods) ) of these three conditions. According to their different causes, they can be divided into glacier melting debris flow, glacier avalanche debris flow and glacial lake outburst debris flow.
The China-Pakistan Karakoram Highway, which connects China and Pakistan, passes through the Karakoram-Himalayan region. Under the influence of many environmental factors such as disparate terrain drop, frequent earthquakes, active glacier movement and extreme rainfall, glacial debris flows are extremely developed, making this one of the most dangerous roads in the world.