The climate in Central Asia underwent irreversible change 30 years ago, becoming hotter and drier, and the Mongolian plateau — as well as parts of the U.S. southwest — could soon be subject to the same arid conditions.
Academics writing in the journal Science, and quoted by the Utah State University press service, said the conditions were created by a “vicious circle” of heat waves — discovered by observing the rings of Siberian larch trees in Mongolia and neighbouring countries.
The conifers, they said, undergo the strongest reactions to abnormally high temperatures. An analysis of the tree’s rings showed that larches were suffering from unprecedented drought and the highest temperatures recorded in the last 250 years.
By measuring the width, colour and other properties of the rings, researchers said the climate in Central Asia was altered in irreversible fashion against a background of constant heat waves in the 1990s.The unprecedented rise in average temperatures over the years led to a ripple of repetitive processes of drying out the soil – which contributed to a rise in temperatures.
When soil is moist, evaporation humidifies the air and surface of the earth — but if there is no moisture, heat transfers directly to the air. That results in new and more frequent heat waves and researchers are unable to say when this process might end.
Academics believe that a series of recent heatwaves in Europe and North America are directly linked to moisture in the soil and the state of the air on the Earth’s surface. They say that the semi-arid climate of the region has entered a new phase in which moisture in the soil no longer reduces abnormally high air temperatures.
The number of lakes on Mongolia’s plateau has already been seriously reduced – Chinese academics in 2014 found a 26 % fall in the umber of lakes with a surface area greater than one sq. km. Even greater reductions were noted in larger bodies of water.
“Now we are seeing that it isn’t just large bodies of water that are disappearing,” said Jee-Hoon Jeong of Chonnam National University in South Korea, one of the authors of the research. “The water in the soil is vanishing, too.” The researchers concluded that this could have disastrous consequences for the region’s ecosystems, including the herbivores within them.