The third pole of the earth includes the Qinghai-Tibet Plateau and its surrounding mountains, known as the "water tower of Asia", and has the world's largest alpine ecosystem. On April 28, the reporter learned from the Institute of Tibetan Plateau of the Chinese Academy of Sciences that the United Nations Environment Programme released the "Third Pole Environmental Science Assessment Report".
The report shows that the Third Pole region has shown an overall warming and wetting trend in the past two thousand years, resulting in rapid changes in water bodies in the past 30 years, and the intensification of the water cycle has led to frequent geological disasters such as glacial lake collapse and ice avalanche. Ecosystems in the Third Pole region have generally improved since the 1980s, and biodiversity has remained well under anthropogenic conservation interventions, but it still faces many challenges, including climate change.
More than 10,000 lakes in the Third Pole provide freshwater sources
The Third Pole of the Earth includes the Qinghai-Tibet Plateau and its surroundings, west to the Pamir-Hindu Kush Mountains, east to the Hengduan Mountains, north to the Tianshan Mountains and qilian Mountains, and south to the Himalayas, the water tower of Asia, with the world's largest alpine ecosystem. With a total area of more than 5 million square kilometers and an area of about 100,000 square kilometers of snow and ice, the Third Pole is the largest ice and snow reservoir on Earth outside the North and South Poles.
The Tibetan Plateau, the rolling glaciers of Coco Siri. Figure/IC photo
As the world's highest ecosystem, the area has developed 14 world-class peaks and provided fresh water for more than 12,000 lakes and more than 10 major river basins. Because of its vast area and complex and diverse ecosystems, the Third Pole is of great significance in terms of climate change, hydrological cycles and changes in the terrestrial surface environment. It is not only an important Asian water tower, but also has a unique alpine ecosystem and biodiversity, which is of great significance to many peoples and countries.
Alpine ecosystems at the third pole are fragile, and global warming is having a much higher impact on the region than other regions. In the context of global warming, the third pole glaciers are melting at an accelerated pace, and ice avalanches and glacial lake ruptures are frequent. Environmental change has a direct impact on the stability of water towers in Asia, which in turn threatens ecosystems, biodiversity and the daily lives of ordinary people. This requires a better understanding of the science of climate warming and its impact on ecosystems in order to provide decision makers with information and recommendations on disaster mitigation and adaptation to achieve sustainable regional development.
Warming and humidity lead to frequent natural disasters related to the cryosphere
The report presents the latest research findings on the climate, water bodies, ecosystems and biodiversity, surface changes and human impacts of the Third Pole.
Ice core and tree ring paleoclimate indicators show that the third pole climate has experienced multiple cold and warm events and has shown an overall warming and wetting trend over the past two millennia. Warming intensified further in the 20th century and peaked in this century. Similar to the warming trend, the increase in precipitation began in the 20th century and continues to this day.
On the Qinghai-Tibet Plateau, the meltwater of the glacier snow mountains forms a plateau water system. Figure/IC photo
As a result of changes in temperature and precipitation, glacier area and mass in the Third Pole region have decreased, with more glacial matter loss in the Himalayas and less glacial matter loss in the Hinterland of the Third Pole. This change has also led to the frequent occurrence of natural disasters related to the cryosphere in recent years. There are indications that the frequency of natural disasters will increase in the future as the climate changes. Snow thickness, area and duration have decreased over the past few decades. At the same time, the runoff of most major rivers in the Third Pole region has an increasing trend.
External human activities have a negative effect on the third pole environment
The report notes that human activities outside the Third Pole, including air pollution such as black carbon emissions, heavy metal pollution and persistent organic pollutants, have a negative impact on the environment in the region.
Studies have found that the Indian monsoon, the westerly belt and local circulation systems (e.g., valley winds) may all transport pollutants from different source regions to the sky above the third pole. Although the current levels of atmospheric pollutants such as black carbon, heavy metals and persistent organic pollutants in the Third Pole region are relatively low compared to cities, there is an upward trend. The transport of atmospheric pollutants from neighboring countries to the Third Pole is not only harmful to human health, but also accelerates glacier melting.
Biodiversity is well maintained under anthropogenic conservation interventions
The Third Pole is one of the most biodiverse regions in the world, home to rare and endangered species of flora and fauna on Earth. Although there is a greater threat to biodiversity on Earth, with genocide rates of about 20 per cent, the extinction rate of vertebrate species in the Third Pole is about 9 per cent and the extinction rate of plant species is about 5 per cent.
Due to the conservation of some Third Pole countries, the number of some species has increased, such as Przewalski's hartebeest and Tibetan wild ass. The report believes that it is necessary to survey biological species in the third pole, obtain basic data on biodiversity, increase cross-border conservation efforts, enhance public awareness of conservation, further improve monitoring and management capabilities, and strengthen law enforcement. Establish early warning mechanisms for invasive alien species to mitigate the ecological effects of climate change.
Tibetan wild donkey migrating in the snow of Coco Siri. Figure/IC photo
The Third Pole will warm further and wetter by the end of the 21st century
Model projections indicate that the temperature of the third pole will rise by 1.4-5.6°C in the late 21st century compared to the reference period (1995-2014). If the global warming rate had been maintained at 1.5°C by the end of the century, the rate of warming that would have intensified with elevation would have remained at 1.8±0.4°C, and the model estimates that precipitation would increase by a corresponding 6%-15% by the end of the 21st century.
Scientific projections suggest that a warmer, wetter climate in the future will have consequences that cannot be ignored. In the next century, glacial ice reserves will decline rapidly, and glacial material in the southeast of the Third Pole region will be reduced by 2/3 compared to today. In addition, the area of snow cover will also be significantly reduced in the next century, which in turn will have a significant impact on the seasonal replenishment of river runoff.
The domino effect of changes in temperature and precipitation projections will significantly affect the cryosphere and hydrosphere, which in turn affect ecosystems and biodiversity. Increased temperature and precipitation will enhance plant photosynthesis. Vegetation distribution will "march" towards higher elevations. Ecological models estimate that this trend will significantly increase the risk of extinction of species with narrow survival intervals and other species in climate-sensitive areas, such as the plateau sand lizard.
Beijing News reporter Zhang Lu
Edited by Chen Jing, proofread by Li Lijun