What is the root cause of sea level rise?

From 1980 to 20 10, the global average temperature increased by 0. 17℃ every 10 year. Due to the melting of ice sheets and glaciers, the sea level rose by 2.3mm every year from 2005 to 20 10. Scientists say that since 1993, half of the sea level rise is caused by the thermal expansion of the ocean, and the other half is caused by the melting of glaciers. Because of absorbing heat from the atmosphere, the temperature of the ocean has increased by about 27 degrees, which is also the main reason for the rise of sea level.

Sea level introduction

Sea level refers to the calm ideal sea surface, and the water level is the average of the observation results. In essence, the average sea level J can be divided into daily average sea level, monthly average sea level, annual average sea level and multi-year average sea level according to different observation time. The first three are influenced by weather, climate or celestial movement.

For a fixed location, the sea level is relatively stable for a long time, and it is often used as the reference point of elevation measurement system. There is no uniform benchmark in the world. China stipulates that the average sea level of the Yellow Sea determined by the statistical data of Qingdao Tidal Observatory 1956 is the national unified elevation starting surface, and the elevation indicated on the map of China is calculated from this sea level as the starting point.