Focus – The Earth is changing shape faster than before

WASHINGTON, Oct 3 /ATSH/ – A new scientific study shows that the shape of the solid Earth is undergoing measurable changes, with polar areas rising faster and regions near the equator gradually sinking, according to “Daily Galaxy”.

The research, published in the journal “Journal of Geophysical Research”, analyses movements of the planet’s surface during the period 1997–2015, revealing that these processes have accelerated over the years.

According to researcher Christopher Kotsakis, from the Aristotle University of Thessaloniki in Greece, data collected from a global network of GNSS satellite stations show changes in the height of the Earth’s surface.

In the period 1997–2000, polar areas were rising by around 0.5 millimetres a year, while by 2015 this rate reached approximately 1.0 millimetre a year.

The changes are partly linked to the melting of ice in Greenland and Antarctica.

When ice sheets lose mass, the weight pressing on the land beneath them decreases, allowing the surface to rise gradually. Meanwhile, the meltwater passes into the oceans, redistributing mass across the planet and affecting the load on the seabed.

Scientists explain that the Earth is not a perfect sphere, as its rotation creates a slight bulge at the equator and a flattening at the poles.

According to the study’s results, the rise of polar areas and the sinking of equatorial regions make the shape of the solid Earth slightly less flattened. This change is very small and cannot be noticed with the naked eye.

Another important aspect of the research is the distinction between the planet’s physical surface and the geoid, which represents the shape linked to the Earth’s gravitational field.

While the solid surface may become less flattened, the redistribution of water and mass may affect the gravitational shape in the opposite direction.

The observed movements are part of long-term processes affecting the planet, including the land’s adjustment after the disappearance of the large ice sheets during the last ice age. Although that period ended thousands of years ago, the Earth’s crust and mantle continue to react to changes in load. Modern ice loss adds another factor to this dynamic.

Researchers use precise satellite measurements to record changes at the millimetre level and to better understand the link between climate, oceans, gravity and the Earth’s structure. These data can help in studying sea-level changes, because not only the water changes height, but the land and seabed can also move. / /Ad.Ab./ a.jor.