Shifting Of Earth’s Axis

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    According to the study published in Geophysical Research Letters of the American Geophysical Union (AGU), the significant melting of glaciers because of global temperature rise is causing movement of Earth’s axis of rotation more than usual since the 1990s.

    Earth’s Axis Of Rotation

    • It is the line along which it spins around itself as it revolves around the Sun.
    • The points on which the axis intersects the planet’s surface are the geographical north and south poles.

    Image Courtesy: Universetoday

    • The location of the poles is not fixed, however, as the axis moves due to changes in how the Earth’s mass is distributed around the planet. Thus, the poles move when the axis moves, and the movement is called “polar motion”.
    • Generally, polar motion is caused by changes in the hydrosphere, atmosphere, oceans, or solid Earth. But now, climate change is adding to the degree with which the poles wander.
    • According to NASA, data from the 20th century shows that the spin axis drifted about 10 centimetres per year

    Major Highlights of The Study

    • Since the 1990s, climate change has caused billions of tonnes of glacial ice to melt into oceans. This has caused the Earth’s poles to move in new directions.
    • As per the study, the north pole has shifted in a new eastward direction since the 1990s, because of changes in the hydrosphere (meaning the way in which water is stored on Earth).
    • From 1995 to 2020, the average speed of drift was 17 times faster than from 1981 to 1995. Also, in the last four decades, the poles moved by about 4 metres in distance.
    • The calculations were based on satellite data from NASA’s Gravity Recovery and Climate Experiment (GRACE) mission as well as estimates of glacier loss and groundwater pumping.

    Factor responsible for change of the polar drift 

    • The faster ice melting under global warming was the most likely cause of the directional change of the polar drift in the 1990s.
    • The other possible causes are (terrestrial water storage) change in non?glacial regions due to climate change and unsustainable consumption of groundwater for irrigation and other anthropogenic activities.

    Gravity Recovery and Climate Experiment (GRACE) Mission 

     

    • It was a joint mission of NASA and the German Aerospace Center (DLR), now, the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission is the successor of this.
      • The GRACE orbited Earth from 2002-2017 and now GRACE FO is in working.
    • Purpose: It measures variations in gravity over Earth’s surface, producing a new map of the gravity field every 30 days.
      • GRACE-FO will continue the work of tracking Earth’s water movement to monitor changes in underground water storage, the amount of water in large lakes and rivers, soil moisture, ice sheets and glaciers, and sea level caused by the addition of water to the ocean.

    Source: IE