Two new studies published by ETH Zurich suggest that the Earth’s rotation is being significantly impacted by climate change.
The research, supported by NASA, explored how climate change is altering the length of the day on Earth and polar motion.
Climate change is causing ice masses in Greenland and Antarctica to melt, with water from both regions flowing into the world’s oceans, which is impacting the rotation of the planet.
Benedikt Soja, Professor of Space Geodesy at the Department of Civil, Environmental and Geomatic Engineering at ETH Zurich, explained: “This means that a shift in mass is taking place, and this is affecting the Earth’s rotation.
“It’s like when a figure skater does a pirouette, first holding her arms close to her body and then stretching them out.
“The initially fast rotation becomes slower because the masses move away from the axis of rotation, increasing physical inertia. In physics, we speak of the law of conservation of angular momentum, and this same law also governs the Earth’s rotation.
“If the Earth turns more slowly, the days get longer. Climate change is, therefore, also altering the length of the day on Earth, albeit only minimally.”
Leveraging AI technology
In their study, the researchers used physics-informed neural networks, which are advanced AI methods that integrate the principles of physics to create robust machine learning algorithms.
These algorithms uniquely capture and model the various interactions between the Earth’s surface, mantle, and core.
The resulting calculations accurately trace the movement of the Earth’s rotational poles since 1900.
These model predictions align closely with historical astronomical observations and recent satellite data, enabling reliable future forecasts.
Influence of climate change on Earth’s rotational speed
The first study revealed that climate change is extending the length of a day by a few milliseconds from its current 86,400 seconds.
This occurs as water moves from the poles to lower latitudes, slowing Earth’s rotation. Tidal friction from the Moon also contributes to this slowdown.
However, the study concludes that continued greenhouse gas emissions and global warming could ultimately impact Earth’s rotational speed more than the Moon, a factor for billions of years.
Additionally, shifts in mass caused by melting ice and internal Earth processes not only alter rotational speed and day length but also the axis of rotation, as detailed in the second study.
This causes polar motion, where the points where Earth’s axis meets the surface shift by about ten metres per hundred years. Besides ice melt, movements in Earth’s mantle and heat flows in the liquid metal of Earth’s outer core contribute to these changes.
The study highlights the interconnection of Earth’s processes, noting that climate change affects the Earth’s axis and may alter the dynamics of the core.
The researchers added that ongoing climate change could influence processes deep within Earth more than previously thought. However, these effects are minor and unlikely to pose a significant risk.
