At the tidal waves that lead the Mongolian climate to a turning point
According to the International Group of Climate Scientists, Mongolia’s semi-arid plateau could soon become as barren as parts of the southwestern United States due to the “vicious cycle” of heat waves, which deepens the drying of the soil and eventually produces more heat waves.
Writing in a magazine Science:Researchers warn that over the past two decades, the number of heat waves and droughts has risen sharply, with far-reaching consequences. Using data from tree rings that provide a glimpse of the regional climate ahead of modern weather logs, researchers have developed records of heat waves և soil moisture that suggest record high temperatures and droughts in recent years are unprecedented in more than 250 years.
According to the study, record high temperatures in the region are accelerating due to soil drying, and together these changes are increasing soil water loss. “The result,” said Deliang Chen, co-author of the University of Gothenburg in Sweden, “is that there are more heat waves, which means more groundwater losses, which means more heat waves, where that can end.” We can not say. “
When the soil is wet, evaporation cools the air to the surface. However, when the soil no longer has moisture, the heat is immediately transferred to the air. In their paper, Beyond the Revolution, a sharp transition to a warmer, drier climate in inland East Asia, the authors note that the last 260 years alone have “shown significant fluctuations in the frequency of heat waves, including soil moisture.” Scientists note that in Europe, a number of recent heat waves in North America have revealed a link between nearby surface air and soil moisture, suggesting that “the region’s semi-arid climate has entered a new mode in which soil moisture is no longer abnormally reduced.” high air temperature. “
Already, the Mongolian plateau lakes have been rapidly shrinking. As of 2014, researchers from China found that the number of lakes per square kilometer decreased by 26%, with even greater reductions in the size of the largest lakes in the region.
“Now we see that not only large masses of water are disappearing,” said e-Hun Je Yeong, a corresponding author from South Korea’s Chonnam National University. “Water in the soil also disappears.”
“It can be devastating to the region’s ecosystem, which is important for large herbivores such as wild sheep, antelope and camels,” said Peng Hang Ang, lead researcher at the University of Gothenburg. “These amazing animals are already living on the edge. These effects of climate change can drive them.”
Jin Yin-ho Yoon, co-author of the Guangzhou Institute of Science and Technology in South Korea, said that data from the centennial of tree rings make it clear that the mixture of hot summer droughts and droughts is unique in the context of the past. 260 years from the University of Gothenburg, co-author Hans Linderholm said that the trees used in the analysis seem to “feel” the heat waves throughout their lives.
“Conifers respond strongly to abnormally high temperatures,” said Linderholm. “Looking at their growth rings, we can see how they have reacted to the latest heat waves. We can see that they do not seem to have had anything like this in their very long lives.”
The tree rings studied during the study were mainly collected from the Mongolian Plateau, which suggests that rising temperatures are affecting plants even at high altitudes.
Daniel Griffin, of the Department of Geography, Environment and Society at the University of Minnesota, who was not involved in the study but who reviewed the article, said the long-term outlook for these tree rings shows a subtle picture of the changing climate now afflicting Inland East Asia. large areas of the region.
“One thing is for sure, the ‘normal’ climate is changing. However, what worries me the most is thinking about the extreme events of the future. How cruel can they become? ” Griffin asked. “And if the ‘new normal’ is too hot-dry by historical standards, future extremes may not be what they used to be.”
Although there are warmer and drier trends in Europe and Asia, Mongolia and its environs are of particular interest to climate scientists, as this region of Inner East Asia is closely linked to global atmospheric circulation.
“Summer atmospheric waves tend to create a high-pressure mountain range around Mongolia that can last for weeks, generating heat waves,” said Simon Wang, co-author of Utah State University. “The mingling climate is amplifying these atmospheric waves, increasing the likelihood of prolonged or intensified high pressure on Mongolia; it may have branches in the Northern Hemisphere.”
“Such large-scale atmospheric force is further enhanced by local interactions with the land surface,” said co-author Hyunjun Kim of the University of Tokyo in Japan. “It is possible that a worse problem has already arisen, as a result of which irreversible feedback is created, accelerating the region towards a hotter and drier future.”
Indeed, researchers have found that recent heat waves have brought warmer air under a higher pressure range than previous heat waves.
The research team found that the overlap between warming and drying seems to be approaching a “turning point” – potentially irreversible, which could push Mongolia into a state of permanent dryness.
Reference. “Abrupt Transition from East Ang to a Warmer, Dryer Climate in Inner East Asia” by Zhang, P., J.-H. Ong eong, -.- H. Yun, H. Kim, S.-Y. Wang, HW Linderholm, K. Fang, X. Wu, D. Chen, 27 November 2020, Science:,