The research published by scientists in the journal Geophysical Research Letters on June 15 has reported that there is a measurable tilt in the Earth’s axis due to anthropogenic factors (direct or indirect environmental change caused by people). The major reason for this shift is unchecked groundwater extraction. During the years 1993-2010, the recorded groundwater extraction from the underground reservoirs was 2,150 Giga tonnes which led to the shift of the North Pole by 80cm towards the East.
Let’s take an example of a filled ball to understand the concept. Imagine there is a filled ball that makes an angle while rotating around a fixed axis. If some material extraction from the filled ball, it will start tilting towards the vacuum created due to extraction. The fixed axis of the ball will also sway towards the vacuum created. The reason is the shift of the internal mass distribution. The same applies to planetary objects like our Earth.
Scientists have discovered that these planetary wobbles are natural. There is a change in the Earth’s axis due to natural forces like movements in the ocean currents and changes in atmospheric masses while seasonal changes. These causes led the Earth’s poles to shift every year by several meters. One of the causes stated for the shift in the rotational axis of Earth is a shift in the distribution of the mass of water and the extraction of groundwater.
It has been observed that the amount of groundwater extraction during the study period from the year 1993 to 2010 corresponds to the amount of water required to cause the sea level to rise by 6 millimetres. However, the exact data is difficult to measure.
Before 2016, scientists claimed that there is a shift in the Earth’s rotational axis due to the redistribution of water like the shrinking of ice sheets in Antarctica or Greenland. But in the year 2016, Surendra Adhikari, scientist at the Jet Propulsion Laboratory, NASA with his team claimed that the change in Earth, rotational axis is also due to land water distribution.
According to the findings of the study conducted in the year 2016, there was a shift in the Earth’s rotational axis due to a massive loss of groundwater in the Indian subcontinent and the Caspian Sea. Since then scientists are working on enquiring how the shift in the rotational axis is caused by the land water redistribution focusing on the mid-latitude region of the planet. The mid-latitude regions of North America and northwest India were reported for the maximum groundwater extraction during the mentioned study period of 1993-2010.
Ki-Weon Seo, the corresponding author for the findings of the study mentioned how the drift can be minimised due to land water redistribution. It can be done by slowing down the groundwater depletion rate in the sensitive areas but this approach should be applied for almost a decade to get the desired result.
Seo, along with his team have considered ice sheets, glacier melting and groundwater extraction as the reason behind the shift in the rotational axis of the Earth but released that only melted water is not responsible for the shift so probably it was the effect of the massive groundwater extraction.
In the year 2021, a study was published in the Geophysical Research Letters that reported the shift of the north pole in the year 1995. The shift became 17 times speedier during the year 1995-2020 as compared to 1981-1995.