'The third pole' of the Earth is melting

In addition to the north and south poles of the Earth, there is another place called "the third pole" because of its importance to human life: the Tibetan plateau and the surrounding mountains.

Among the changes in the Earth's surface due to temperature changes, melting is considered the most important. It changes everything, from the land below, the air above and the surrounding life. That's why climatologists care about the north and south poles of the Earth. But these two poles are just two examples and it would be better to study a third pole that is equally important.

The "third pole" of the globe

Although the amount of ice on the Tibetan plateau and the surrounding mountains (such as the Himalayas, Karakoram and Pamirs) are much smaller than at the poles of the Earth, it is still a giant block of ice. About 46,000 of the region's glaciers cover an area of ​​100,000 square kilometers, about 6 percent of the Greenland ice area. In addition, an area of ​​about 1.7 million square kilometers is a permafrost area, which can be as thick as 130 meters, equivalent to 7 percent of the permafrost area in the Arctic.

Unlike ice at the poles, the fate of the ice here directly affects the lives of many people. The Tibetan Plateau and the surrounding mountains are known as Asia's water towers, because it is the source of 10 of the continent's largest rivers (including the Mekong). About 1.5 billion people from 12 countries live in these river basins. So the Tibetan plateau and the surrounding areas are called the "third pole" of the Earth.

Until recently, studies of the "third pole" were still very fragmented. However, since 2009 there has been an international program called "The Third Extreme Environment" (TPE) initiated by three scientists: Cao Dam Dong of the Tibetan Plateau Research Institute in Beijing (China ), Lonnie Thompson of Ohio State University (USA) and Volker Mosbrugger of Senckenberg Biodiversity World University in Frankfurt (Germany). Last month, the fourth TPE conference took place in Dehradun, India.

Difficulties in research

One question is whether the glaciers at the "third pole" are decreasing as they are at one part of the other two poles? The report of the Intergovernmental Panel on Climate Change in 2007 once suggested that the glaciers in the Himalayas would disappear soon in 2035. But this assessment was quickly rejected.

Last year, a study published in Thomas Jacob's Nature magazine of the University of Colorado showed that glaciers in the Himalayas and Karakoram had lost ice between 2003 and 2010, while ice on glaciers in the Tibetan plateau again. increase. However, many glacier researchers disagree with this conclusion.

At the TPE conference, Dr. Tobias Bolch of the University of Zurich explained that Thomas Jacob's research is based on a seven-year measurement of GRACE satellites using an orbital gravity measuring device to measure change of ice cover from the impact on the gravity field of this area.

According to Dr. Bolch, this study encountered two problems. The first is the weak analysis of satellite devices, which cannot determine changes in specific points below a distance of 200km. This ability is only enough to study large areas with homogeneous surfaces such as the Arctic and Antarctic. However, for hilly terrain, the measurement is more complicated.

The third "polar" map of the Earth with the associated mountains and large rivers - (Photo: The Economist)

Second, the more serious problem is that satellites cannot distinguish the difference between solid and liquid water. If a glacier melts but the water is retained as a lake, GRACE will not see a change. While in the Tibetan Plateau there are many "closed" basins (where melting water does not easily escape), a large amount of ice can melt and GRACE is unidentified.

Indeed, a statistic of Dr. Cao and his colleagues showed that the area of ​​glacial lakes on the Tibetan plateau has increased by about 26% since the 1970s. Dr. Bolch suspected that GRACE had mistaken these extended lakes. with big glaciers. Using another satellite called ICESat, which borrowed lasers to measure not only glacier areas, but also the thickening of the surface of those glaciers, Dr. Bolch and colleagues concluded that many glaciers in Tibet is being reduced.

But not all glaciers meet this situation. What Dr. Bolch found supported the works of Dr. Cao and Thompson, who studied reports and satellite images of more than 7,100 glaciers, collected over the past 30 years, not just seven the glacier that GRACE monitors.

Some glaciers are rising, mostly in Karakoram and Pamirs. But glaciers in the eastern Himalaya and western Tibetan plateau are rapidly declining. Glaciers in the middle of the Tibetan plateau are also declining although slower. The result is a large amount of ice lost during the period from 2003-2010 mentioned above.

Climate Change

In an effort to understand what's going on, Dr. Cao and Thompson consulted the weather data. For decades, the monsoon in India, which brought snow to the south of Tibet and the eastern and central regions of the Himalayas, has become weaker, though it is unclear why. However, westerly winds bring snow to Karakoram and Pamirs become stronger.

The west wind is generated by hot air rising from the oceans and moving north (hot air moves from warm to cold) and to the east (because Coriolis force is born from the rotation of the Earth. ). Global warming also means more hot air rises, so the west wind is stronger.

The monsoon comes in summer, the west wind comes in winter. The warmer climate seems to prevent summer snow from accumulating rather than winter snow. In short, changes in wind power and air temperature explain what is going on. And not just glaciers are melting.

According to researcher Vu Khanh Bach of the Institute for Environmental Studies and Structure of Cold and Arid Areas in Lanzhou (China), permafrost in Tibet is also melting rapidly in the past two decades.

Himalayan mission

A conclusion is drawn after the TPE conference: the entire ice sheet at the "third pole" , as well as at the two poles of the Earth, is melting. Another conclusion also shows how the data for the "third pole" is uncertain and fragmented. Therefore, the Chinese Academy of Sciences, where the institutes of Dr. Cao and Vu belong, have created a fund of 400 million yuan (about 65 million USD) to study "the third pole" and the important one. / 4 funds are used for research outside China.

From now on, researchers will follow a group of mainstream glaciers every six months. They will set up observation stations to measure solar radiation, snowfall, melting water and soil changes as well as air temperature, pressure, humidity and wind, and plan to take the core in ice. on the Tibetan plateau. These will help rebuild the climate of this area within hundreds of thousands of years. Thus they will better understand how much and why the "third pole" is changing.