NASA: Earth Surface Mass has deviated

The National Aeronautics and Space Administration recently announced that the Earth Mass has deviated in August 2020 as compared to that of 2004-09. According to NASA, the sea level increase may be due to the change in earth mass.

Findings of NASA

The change in earth mass is mainly caused due to land movement relative to sea. The changes in land movement was more in snow- and ice-covered regions. This is because, here the ice cover is disappearing. In other words, here the surface mass of the earth is being lost.

NASA released maps showing how several factors affect the sea level increase.

Land Motion

The natural drivers such as shifting of tectonic plates, compression of buried ocean sediments produce gradual motion. Apart from these, the human driven factors such as ground water extraction, oil production and drying of peat soils also cause land motion.

The Global Navigation Satellite System (GNSS) helped analyse land movement. According to NASA, oil production and ground water extraction can produce subsidence at the rate of centimetres per year as compared to milli metres per year as caused by natural processes.

Ocean Alimetry

The Alimetry missions of Oceans are used to learn about ocean topography. The Radar Alimeters send out pulses of radio waves that bounce the surface of ocean and reflect back towards the satellite. The satellite calculates the time taken for the signal to return. Using this, the scientists can determine the height of the sea.

Reasons for change in earth masses

The changes were mainly because changes in amount of water, ice and snow. These changes were calculated by GRACE Mission. It was a joint mission by NASA and Germany. GRACE mission found that there were mass losses of Greenland ice sheet between 2002 and 2016. Also, the mission found that between 2002 and 2017, there were mass losses of 1.2 milli metres per year.

Greenland

The losses in ice masses in Greenland was more than that of Antarctica. Greenland lost around 200 Gigatonnes of ice per year from its coastal glaciers alone.

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