Permafrost is mainly distributed in the Antarctic, Arctic and some countries near the Arctic Circle, as well as high-altitude areas in China, Russia and Europe. According to data provided by the International Frozen Soil Association, permafrost occupies approximately 25% of the land in the northern hemisphere, and 63% of Russian territory is located above permafrost. In my country, the area of permafrost accounts for 21.5% of the total area of the country, most of which are distributed in the Greater Khingan Mountains, Qinghai-Tibet Plateau, Qilian Mountains and Himalayas.
Unlike the desolate scene in the imagination, the permafrost is rich in fresh water, minerals, forests and other resources, and its water content accounts for 69% of the earth's available fresh water resources. Studies have shown that the carbon content in permafrost is about 1.6 trillion tons, which is about 1/3 of the total carbon in the world's soil and twice the carbon content in the atmosphere.
Climate change will cause the permafrost to melt rapidly. Experts predict that by the end of this century, the Arctic permafrost, once the size of Russia, may shrink to the size of Alaska.
In the context of global warming, a series of ecological and environmental changes have occurred in cold regions that are extremely sensitive to climate change, such as permafrost degradation. Part of the permafrost regions are degraded into seasonal frozen soil regions. At the same time, the maximum freezing depth of permafrost is also changing. Studies have shown that the degradation of frozen soil has caused the increase in winter (dry season) runoff, the decrease in summer runoff, and the slowing down of the annual runoff process.
Once the frozen soil melts, the environmental changes and the harm to humans caused should not be underestimated. Mainly include:
mercury poisoning. According to statistics from the United Nations Environment Department, 56,700 cubic meters of mercury are stored in the Arctic permafrost. The most immediate problem caused by the melting of permafrost is mercury poisoning.
Geological disaster. Due to the thawing of frozen soil due to climate change, cities built on permafrost in Siberia, Russia, will face the threat of collapse in the next 35 years. By 2050, the land carrying capacity of these permafrost regions may be reduced by 75% to 95%. The fundamental reason for the devastating disasters in these cities is the repeated freezing and thawing of the surface rock and soil in the frozen soil area due to temperature changes, that is, freezing and thawing.
Freezing and thawing can cause a variety of geological disasters, such as frost heave, thermal thawing collapse, and thermal thawing subsidence. These disasters often damage railways, highways, bridges, houses and other engineering facilities, resulting in swelling or subsidence of roadbeds, cracking and deformation of houses, etc. The loess collapse accident that occurred in Yangqu County, Shanxi Province in 2010 was a large-scale collapse of geological disasters caused by a sudden rise in temperature and rapid thawing of surface frozen soil.
In recent years, the permafrost regions of my country's Qinghai-Tibet Plateau have undergone many freezing and thawing effects due to changes in the natural environment and human activities. At present, the permafrost in the Qinghai-Tibet Project Corridor is degraded significantly, freezing and thawing disasters are increasing, and the alpine ecosystem is facing new challenges.
Ecological deterioration. The water seeping out when the frozen soil melts, as well as the increase in melting water from glaciers and rising temperatures, may promote the growth of vegetation on the plateau in the short term, resulting in partial improvement of Tibet's ecosystem. However, in the long run, the weakening or loss of the water conservation function of frozen soil may cause soil drought in the frozen soil area, trigger and aggravate the degradation of the alpine grassland on the Qinghai-Tibet Plateau, thereby further deteriorating the ecology of the Qinghai-Tibet Plateau.
Related studies on alpine meadows in the Naqu Basin of Tibet show that as the frequency of freezing and thawing increases, the root damage of alpine meadows increases, and the ability of symbiotic nitrogen fixation and disease resistance is significantly reduced, which will accelerate the loss of soil nutrients and the freezing process. Increase the damage to the soil structure. Under this series of influences, the biomass of alpine meadows in the Naqu Basin of Tibet will eventually decrease, and the growth and survival of alpine meadows will be threatened.
Release greenhouse gases and ancient viruses. What worries the scientific community even more is that in the Arctic permafrost, there are a large amount of greenhouse gases (methane and carbon dioxide, etc.) that have accumulated for tens of thousands of years, and there are even "sleeping" ancient viruses. Once the frozen ground melts, it is likely to release these "devils" outwards.
Scientists have found the remains of a 1918 flu victim in Alaska's permafrost, reconstructed the virus through modern technology, and used it to infect cells and mice cultured in vitro. The results show that the virus's ability to infect mice and to cause disease is stronger than the existing influenza virus.
In addition, American and German researchers have discovered that the formation of a lake called "thermokarst" causes the sudden melting of the Arctic permafrost. Studies have shown that a large amount of ice in the frozen soil layer becomes smaller after melting into water, causing the surface to sink. Rain and melting water fill it into a "hot karst" lake, and the lake water will cause the shore and lake bottom frozen soil layer to suddenly melt. The rate of global warming caused by the melting of frozen soil is at least twice as fast as previously predicted.
Scientists estimate that if the Arctic permafrost is completely melted, the amount of greenhouse gases in the atmosphere will double the current level, causing the global average temperature to rise by 3.5 degrees Celsius. The high temperature will evaporate more rivers, leading to large-scale droughts and desert climates, and the frequency of extreme weather such as hurricanes, heat waves, heavy rains, wildfires, and droughts will increase.
