The new height of Mount Everest refers to the International Height Reference System (IHRS), a major enterprise of GGOS.

In December 2020, the Chinese and Nepalese Governments announced the new height of Mount Everest. Heights are usually determined with respect to the mean sea level registered at a tide gauge. Depending on the geographical location of the tide gauge and the time interval considered for averaging the tide gauge records, the height reference level may vary up to 2 m worldwide. Thus, referring the height of a point to different mean sea levels produces different height values for the same point.

The International Association of Geodesy (IAG) and its Global Geodetic Observing System (GGOS) are intensively working on the establishment of a global unified height system that supports the height determination with respect to one and the same reference level worldwide. All concepts needed for this goal are grouped under the International Height Reference System (IHRS) and its establishment is a major enterprise of GGOS (Focus Area Unified Height System).

A prominent example of the importance of the IHRS is the recent height determination of Mount Everest in 2020. Referring this height to the Chinese height system or to the Nepalese height system would produce different values, making difficult to decide which one is the appropriate one. To avoid discrepancies, the Chinese and Nepalese Governments agreed to refer the new Mount Everest’s height of 8848.86 meter to the IHRS,

see http://www.xinhuanet.com/english/2020-12/08/c_139573400.htm.

Author: Laura Sánchez