The Earth seems immobile in its fundamental rules. The sun rises, sets, and each day lasts twenty-four hours. A structure so stable that it seems as natural as breathing. Yet reality is much more dynamic than we imagine. Our planet continually changes pace, like a living organism reacting to what happens on its surface.
In recent years, science has begun to observe a surprising phenomenon: human activities are even influencing the speed with which the Earth spins. This is not a perceptible variation in daily life, but a powerful scientific signal that tells something enormous: climate change is modifying the movement of the planet.
According to research published in the scientific journal JGR Solid Earththe melting of ice and the redistribution of water in the oceans are causing a measurable effect on the Earth’s rotation. The result is tiny, but concrete: the days are getting slightly longer.
How climate change is lengthening the days on Earth
To understand what is happening we need to take a step back in the history of the Planet. When Earth formed about 4.6 billion years ago, a day lasted just six hours. Over the course of geological eras, the planet’s rotation has progressively slowed down until it reaches the current duration of approximately twenty-four hours.
For a long time, scientists have attributed this slowdown mainly to the influence of the Moon, whose gravitational force acts as a sort of natural brake on the Earth’s rotation. However, new studies suggest that today there is a further factor capable of influencing this millennial balance: the impact of human activities on the global climate.
A group of researchers from the University of Vienna has reconstructed the history of the Earth’s rotation over the last 3.6 million years using a surprising natural archive: the fossilized shells of benthic foraminifera, tiny single-celled marine organisms that live on the ocean floor.
When these microorganisms die, they leave behind calcareous shells that preserve valuable chemical information about the environment in which they lived. In practice they work like geological diaries of the past, capable of recording the temperature of the water, the volume of the oceans and the quantity of ice present on the planet at that precise moment.
By analyzing these fossils and integrating the data with a sophisticated artificial intelligence model called Physics-Informed Diffusion Model, researchers were able to reconstruct with great precision how the distribution of water on Earth has changed over time and how this has influenced the planet’s rotation. The result is surprising: current climate change is already having a measurable effect on the length of days.
Why does melting ice slow the Earth?
To understand the mechanism you need to imagine a very simple scene: a figure skater rotating on herself. When the skater keeps her arms tucked close to her body, she spins quickly. However, when it widens them, the rotation slows down. This happens due to a law of physics called conservation of angular momentum, which states that the rotation speed changes when the mass distribution varies. The Earth behaves the same way.
When huge masses of ice remain concentrated at the poles, much of the planet’s mass is found relatively close to the rotation axis. However, when global warming melts these ices, the water flows towards the oceans and is progressively distributed towards the equator. In practice, the mass of the planet moves away from the axis of rotation, just like the skater’s arms. The result is a slowdown, however minimal, of the Earth’s rotation.
Scientists have calculated that this phenomenon is lengthening days by about 1.33 milliseconds per century. A tiny variation for our daily perception of time, but extremely significant from a scientific point of view. Even more surprising is the comparison with the past: according to the data reconstructed in the study, such a rapid change had not occurred in the last million years.
Because this discovery is also important for our daily lives
At first glance it might seem like a purely scientific detail. A few extra milliseconds in the duration of a day certainly won’t change the way we organize our days. In reality this phenomenon tells something much bigger.
When we talk about rising sea levels we immediately think of the most obvious consequences: coasts receding, cities at risk of flooding, aquifers becoming salinised. However, there is also a less visible but equally important effect: the redistribution of the mass of the entire planet. This study demonstrates that oceans, ice, atmosphere and Earth’s crust function as parts of a single interconnected system. Changing one of these elements inevitably means influencing the others too.
Then there is a very concrete aspect that concerns technology. Some modern systems require extreme timing precision to function properly. Let’s think, for example, of GPS systems, Earth observation satellites, space missions and telecommunications.
These technologies must know with great precision the position of the planet and its rotation in space. Even changes of a few milliseconds can require updates in the models used to calculate Earth coordinates. In other words, climate change is not only affecting the environment and ecosystems, but also the way the planet moves through space.
There is something deeply symbolic in this discovery. Humans have burned so many fossil fuels, melted so much ice mass and changed climate balances so profoundly that they have even managed to alter the planet’s rotation rate. This is a tiny variation, imperceptible to our daily experience. Yet, the scientific message is very powerful. For the first time in Earth’s recent history, a species is leaving a measurable imprint on even the time at which the planet spins.
You might also be interested in:
