The global conference of the "Third Pole Environmental Science Assessment Report" was held in the form of a combination of online and offline at the Qinghai-Tibet Plateau Institute of the Chinese Academy of Sciences. Photo by Sun Zifa, a reporter from China News Service
Beijing, April 29 (China News Network) -- The latest comprehensive "physical examination" report of scientists on the third pole of the earth, the "Third Pole Environmental Science Assessment Report", was released by the United Nations Environment Programme at the Beijing Department of the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences on the 28th in a combination of online and offline methods. Including Chinese scientists who contributed to the report, scientists have issued "prescriptions" in the report, pointing out that given the complex interactions of the climate and environment in the third pole, multidisciplinary and interdisciplinary approaches are needed to address many challenges.
Fragile impacts of alpine ecosystems at the third pole of the earth "Asian water tower"
The third pole of the earth includes the Qinghai-Tibet Plateau and its surrounding areas, 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, which is the "Water Tower of Asia" and has the world's largest alpine ecosystem. With a total area of more than 5 million square kilometers and an area covered by about 100,000 square kilometers of ice and snow, the Third Pole is the largest "ice and snow reservoir" on Earth outside the North and South Poles.
As the world's highest ecosystem, the Third Pole region has developed 14 world-class peaks, providing 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 land surface environmental processes. It is not only an important "water tower in Asia", but also a globally important alpine ecosystem and biodiversity, which is of great significance to many peoples and countries.
Yao Tandong, one of the main authors of the "Third Pole Environmental Science Assessment Report", an academician of the Chinese Academy of Sciences and a researcher at the Institute of Tibetan Plateau of the Chinese Academy of Sciences, presented the report at the press conference. Photo by Sun Zifa, a reporter from China News Service
Alpine ecosystems at the third pole are fragile, and global warming affects the region much more than other regions, with accelerated glacier melting and frequent ice avalanches and lagoon ruptures in the context of global warming. Environmental change directly affects the stability of the "Asian Water Tower", which in turn threatens ecosystems, biodiversity and the daily lives of ordinary people. There is a need for a better understanding of the science behind warming and its impacts on ecosystems in order to provide decision makers with information and advice on disaster mitigation and adaptation to achieve sustainable regional development.
Four areas, such as climate change, list the multidisciplinary research community consensus
Similar to the work of the United Nations Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), the Third Pole Environmental Science Assessment Report is the first comprehensive assessment of environmental change in the Third Pole, which sets out a group consensus of multidisciplinary research in four areas: climate change, water bodies, ecosystems and biodiversity and the impacts of human activities.
Ice core and treewheel paleoclimate indicators show that the third pole climate has experienced multiple cold and warm events and has shown overall warming and wetting characteristics over the past two millennia. Warming began in the late 19th century, intensified further in the 20th century, and peaked in the current century. Similar to the warming trend, the increase in precipitation began in the 20th century and continues. Both warming and wetting trends are supported by observations of the third pole over the past few decades, while highlighting seasonal and regional differences, warming at higher elevations is more pronounced, and precipitation from extreme precipitation events is increasing.
As a result of changes in temperature and precipitation, the area and mass of glaciers in the Third Pole region have decreased, and the spatial manifestation is that the Himalayan region has more glacial material losses, while the third pole hinterland has less glacial material loss. This change has also led to the frequent occurrence of cryosphere-related natural disasters in recent years, and there are also signs 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, most of the major river runoff in the third polar region has an increasing trend. The change of flow is closely related to the pattern of precipitation and the factors of glacier melting and replenishment.
The third has a wide variety of ecosystems, the most important of which are grasslands, shrubs and tundra, followed by forests, farmland and wetlands. Forest area, which accounted for 11.5 per cent of the total area in 2005, is being transformed from primary to secondary forest. Farmland is mainly located in the Lhasa and Nianchu river basins, where crops are grown once a year. Forests and wetlands nurture vast terrestrial and aquatic biodiversity, providing a wide variety of ecosystem functions. Ecosystems in the Third Pole region are constantly changing, manifested by an early growing season, increased vegetation cover and increased productivity. The expansion of vegetation coverage has enhanced the soil's ability to conserve water, and the third pole, which once experienced the thickening of the permafrost active layer and the increase in the temperature of the frozen soil, also expanded the desertification area of its main river source area. The overall trend of deterioration in soil quality and the situation of soil erosion have improved after entering the 21st century.
Human activities outside the Third Pole region, 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.
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. Despite the greater threat to biodiversity on Earth, the genocide rate is as high as about 20%, the extinction rate of vertebrate species in the third pole is about 9%, and the extinction rate of plant species is about 5%. Due to the conservation of some Third Pole countries, there are also some species that have increased in numbers, such as Przewalski's hartebeest and Tibetan wild ass. At present, it is necessary to survey the biological species in the area, obtain basic data on biodiversity, increase cross-border conservation efforts, enhance public awareness of conservation, further improve monitoring and management capabilities, strengthen the legal system, promote the effectiveness and longevity of conservation means, and establish an early warning mechanism for invasive alien species, so as to mitigate the ecological effects brought about by climate change.
A warmer and wetter climate in the future will have consequences that cannot be ignored
Scientists have used model predictions to indicate that temperatures at the third pole will rise by 1.4-5.6°C in the late 21st century compared to the reference period (1995-2014). If global warming were to remain at 1.5°C by the end of the century, the warming would increase by 1.8±0.4°C at elevated altitudes, and correspondingly, models predict that precipitation will increase by 6-15% by the end of the 21st century, but regional and seasonal differences will always exist. The model also projects a further increase in winter precipitation in the dominant westerly wind belt and summer precipitation in the monsoon zone.
Scientific projections suggest that a warmer and 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 total runoff of rivers in the Third Pole region will rise, with river runoff in the monsoon-dominant region increasing more than in the westerly dominant region. This spatial difference is mainly caused by the difference in runoff recharge sources, with the monsoon area dominated by precipitation replenishment, while the westerly wind region is dominated by glacial meltwater replenishment. In watersheds where glacial meltwater is the main source of recharge, future runoff will generally rise and will decline steadily after peaking, as the retreat of glaciers caused by warming is no longer sufficient to supply sufficient glacial meltwater. When this inflection point occurs depends on regional variation, the rate of warming, and glacial ice reserves, and varies from river to river.
The domino effect of these projected changes in temperature and precipitation significantly affects the cryosphere and hydrosphere, which in turn affects ecosystems and biodiversity. Increased temperature and precipitation will increase plant photosynthesis and net productivity. Future net productivity varies with region, decreasing from east to west. The "greening" caused by vegetation growth and changes in major species also affects albedo and solar radiation, which in turn produces positive feedback.
Vegetation distribution will march towards higher elevations. Ecological models estimate that this trend will significantly increase the risk of extinction for species with narrow survival ranges and other species in climate-sensitive areas, such as the plateau sand lizard. "Therefore, we need to strengthen protection measures while adhering to evidence-based management measures," the report stresses. Scientists stressed in the Third Pole Environmental Science Assessment Report. (End)