Recent studies reveal that climate change is not only affecting our environment but also the Earth's rotation and the length of our days. Researchers from ETH Zurich, supported by NASA, have uncovered how melting ice masses in Greenland and Antarctica are causing shifts in the Earth's mass distribution, leading to changes in rotational dynamics.
Professor Benedikt Soja of ETH Zurich explains that as water from melting ice flows into the oceans, especially around the equator, it shifts the Earth's mass away from the axis of rotation. This phenomenon is similar to a figure skater extending their arms during a spin, causing the rotation to slow due to increased inertia. This principle is governed by the law of conservation of angular momentum, which dictates that a slower Earth rotation leads to longer days. While these changes are minimal, they highlight the extensive impact of climate change.
Researchers show that climate change is extending the day by a few milliseconds in a ground-breaking study that was published in the Proceedings of the National Academy of Sciences (PNAS). The study highlights that human activities and the resulting greenhouse gas emissions are now more influential in altering the Earth's rotational speed than the moon's tidal forces, which have dominated for billions of years. This revelation underscores the profound impact humans have on our planet's dynamics.
The melting of polar ice is not only slowing the Earth's rotation but also shifting its axis. This shift means that the points where the axis intersects the Earth's surface are moving, a phenomenon known as polar motion. Over a century, these shifts can amount to several meters. Researchers attribute these changes to both surface mass redistribution and internal movements within the Earth's mantle and core.
A comprehensive study published in Nature Geoscience by Soja and his team presents the first complete explanation of long-period polar motion. They used advanced modelling techniques to show how climate-induced surface changes and internal dynamics in the mantle and core are interconnected.
To model these complex interactions, the researchers utilized physics-informed neural networks. This innovative AI method, developed with the expertise of Professor Siddhartha Mishra, Professor of Mathematics at ETH Zurich, combines physical laws with machine learning to create highly accurate models. These models have successfully recorded and predicted the Earth's rotational pole movements since 1900, aligning well with historical astronomical and satellite data.
Understanding these changes is crucial for space navigation. Even minor shifts in the Earth's rotation can significantly impact the accuracy of space missions. For instance, a deviation of just one centimeter on Earth could translate into a miscalculation of hundreds of meters over interplanetary distances, potentially jeopardizing missions to land on specific Martian craters.
The findings from ETH Zurich highlight the far-reaching consequences of climate change, extending even to the Earth's core dynamics. While these effects are minor and not immediately threatening, they serve as a powerful reminder of the interconnectedness of our planet's systems and the significant impact of human activities. As Soja emphasizes, "We humans have a greater impact on our planet than we realize," urging a sense of responsibility for future generations.
