Specific data of global temperature

Yesterday (9th), the State Bureau of Surveying and Mapping released the latest elevation data of Mount Everest to the world: 8844.43m ... This new data is 3.7m lower than that published by 1975.

"When rocks rise, snow falls"

"This does not mean that the height of Mount Qomolangma is decreasing." 1975 Chen Junyong, the designer and organizer of Mount Qomolangma elevation survey and academician of China Academy of Sciences, said yesterday that in the past 30 years, driven by the Eurasian plate, Mount Qomolangma has been growing slowly at an irregular speed, but its ice and snow layers have been decreasing.

An Baosheng, a researcher at the Qinghai-Tibet Plateau Institute of China Academy of Sciences, confirmed to China Business News last night that the top of Mount Everest has been decreasing since 1966, but the main reason for the decrease is the thickness of snow. According to observation, from 1966 to 1999, the top of Mount Everest dropped from 8849.75 meters to 8848.45 meters, with a total drop of 1.3 meters. According to the annual reduction, the reduction at the top of Mount Everest is relatively fast during the period from 1966 to 1975, which is close to 0. 1 m every year. From 1975 to 1992, the descending process is weakened, only 0.01m; From 1992 to 1998, the decline process increases rapidly, approaching 0.1m; From 1998 to 1999, it reaches 0.13m.

Yao Tandong, director of the Qinghai-Tibet Plateau Research Institute of China Academy of Sciences, concluded that the sharp decrease of the top of Mount Qomolangma in a short period of time is definitely not the result of crustal movement, and can only be explained by the response of glaciers to climate. In fact, the period when the top of Mount Qomolangma drops sharply from 1992 corresponds to the period of rapid warming. The annual average temperature in Dingri County, where Mount Everest is located, especially in winter, has obviously increased in recent decades. From 197 1 to 1992, the annual average temperature increased by about 2.6 degrees Celsius, which was 1.7 degrees Celsius higher than that from 1960 to 1967. Since 1993, the annual average temperature has increased more obviously. From 1998 to 2002, the annual average temperature rose continuously above 3.3 degrees Celsius.

Significance of measuring Everest

Wang Fuzhou, one of the earliest mountaineers in China and executive vice chairman and secretary general of China Scientific Investigation Association, said: "The global influence of the height change of Mount Everest and related measurement data can not be ignored." The geological changes of Mount Everest will affect the changes of biosphere, atmosphere and lithosphere, so measuring the altitude of Mount Everest is closely related to people's lives in a sense.

According to experts from the National Basic Geographic Information Center, in April 2004, Vice Premier the State Council approved the 2005 Everest Elevation Survey Report submitted by the State Bureau of Surveying and Mapping, and the Everest Elevation Survey was formally established in the State Bureau of Surveying and Mapping. On the one hand, this high-level survey is to show the national strength, especially the scientific and technological strength, on the other hand, it is also an important part of the national important geographic information survey.

In the Tenth Five-Year Plan, the State Bureau of Surveying and Mapping put forward that it will fully promote the construction of the geospatial framework of digital China and build a1:50,000 digital line map database and meta-database covering about 80% of China's land area. "Organizing the elevation measurement of Mount Everest" was listed as the focus of work in 2005.

The most accurate and reliable data

For this measurement result, Wang Fuzhou thinks it is "the most accurate and reliable data so far".

On July 18, 2005, the State Bureau of Surveying and Mapping and the Bureau of Surveying and Mapping of the General Staff Department jointly held the acceptance review meeting of the "2005 Everest Elevation Survey" project in Beijing. "The question of whether this result will be accepted by the international community was raised at the meeting." Wang Fuzhou said that experts believe that most people will agree with this measurement result and question the specific measurement methods or means at most.

"But I believe this result is credible." Wang Fuzhou explained that foreign scientists and technicians have measured Mount Everest before, but the technical means are not as good as this one.

According to reports, in this survey of Mount Everest, 30 points of GPS monitoring network of Qinghai-Tibet plate movement and 32 points of GPS control network of Mount Everest were set up, and the geoid of this area was refined by means of leveling and gravity measurement, thus accurately determining the starting point of Mount Everest elevation survey and the elevation values of six intersections. After the peak beacon was set up on May 22nd, six intersections were continuously measured for 48 hours with theodolite, laser rangefinder and other equipment. The peak finder performs GPS high-precision positioning, and the radar detector measures the thickness of the ice and snow layer at the target. On June 12, all the field survey data were delivered to the Geodetic Data Processing Center of the State Bureau of Surveying and Mapping in Xi 'an, and then data processing and calculation such as leveling, GPS positioning, triangulation, gravity geoid and radar sounding began. At the same time, the State Bureau of Surveying and Mapping also invited experts from the Chinese Academy of Sciences, the General Staff Bureau of Surveying and Mapping, Wuhan University and other units to conduct a comprehensive inspection of the calculated data to ensure the accuracy of the results.