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The Earth, although spherical, is in no way a perfectly ball-shaped body, its weight is not evenly distributed on the surface. So, while an office globe with a fixed north and south pole rotates smoothly on its axis, the Earth is wobbling on its axis of rotation, the imaginary straight line that connects the North Pole to the South Pole crossing the planet.
This oscillation of the axis of rotation, explains NASA, calls the polar movement and its drift has, during the 20th century, derived from about 10 cm per year. Over a hundred years, this translates to about 10 meters of drift.
NASA has identified three major causes of axial drift using observational data as well as data based on 20th century models: loss of Greenland ice mass, glacial rebound, and mantle convection.
"The traditional explanation is that a process, the glacial rebound, is responsible for this movement of the earth's axis of rotation.But recently, many scholars have speculated that others processes could have significant effects on him, "said the first author Surendra Adhikari. Jet propulsion laboratory.
"We have assembled models for a suite of processes that are considered important to drive the movement of the axis of rotation," he explained. He then identified three series of processes that he describes as "crucial": the merger of the "global cryosphere (especially Greenland) during the twentieth century". Yes, it's related to climate change.
In a generalized view, the redistribution of land mass, both on and off the planet, is known to influence rotation. This includes, but is not limited to, changes in land, ice caps, oceans, and mantle circulation, NASA explains.
The ever increasing global temperatures of the 20th century caused the decline of the Greenland ice mass – in fact, about 7,500 gigatonnes (7,500,000,000,000 tonnes) of Greenland ice melted and fell into the atmosphere. ocean during this century. As a result, Greenland is one of the major contributors to mass transfer in the world's seas, leading to sea-level rise and hence drift on the earth's axis of rotation.
"There is a geometric effect that if you have a 45-degree mass in relation to the North Pole – what Greenland is – or the South Pole (like the Patagonian glaciers), this will have a greater impact on the rotation of the Earth "is close to the pole," said co-author Eric Ivins, also of the JPL.
The article was published for the first time in the Letters of the Earth and Planetary Sciences, entitled "What motivates the polar movement of the twentieth century?
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