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New research, building on data from 2024, reveals that accelerating ice melt is not just slowing Earth’s rotation at a rate unseen in 3.6 million years, but also disrupting global technological systems.
When the Earth was first born 4.5 billion years ago, an average day lasted less than 10 hours. Fast forward to 150 to 180 million years ago, during the time of the dinosaurs, that average expanded to 23 hour long days.
An average day on Earth has been gradually increasing in length for many millenniums since the planet’s formation. This is all happening thanks to Moon in an event referred to as tidal acceleration.
Try visualizing the Earth with the Moon orbiting around it. The Moon’s gravity is the strongest on the side of the Earth that is facing it, causing tidal bulges which are essentially just water on the planet’s surface being pulled elliptically towards the Moon.
Since the Earth rotates much faster than the Moon’s orbit, the Earth’s rotation ends up dragging these tidal bulges ahead of the Moon’s position. At the same time, because of the Moon’s gravitational strength, it pulls back on these bulges, creating a sort of braking effect, effectively slowing the Earth’s spin.
However, in 2020, an anomaly occurred when the planet’s spin was temporarily accelerated driven by complex shifts within the Earth’s internal mass distribution and changes in the ‘Chandler Wobble’.
This boost might be short lived as a major study published just last month confirmed a 2024 paper’s theory that human driven-climate change might just be making our days longer.
Before getting into it, here’s a mini-crash course. The Earth isn’t perfectly round but rather is slightly wider at the equator. This is because its rotation pushes mass outward at the equator. When polar ice melts, the mass redistributes away from the poles and further away from Earth’s rotation axis. This is the supposed cause of slower rotation and fractionally longer days.
Two years ago, Duncan Agnew, a geophysicist, found that the accelerated melting of ice in Antarctica and Greenland was decreasing Earth’s angular momentum, or spin rapidly. This study ended up highlighting a previously overlooked relationship between climate change and time and questioned the need for leap seconds – which we will come back to in a moment.
Then, early last month, two researchers, Mostafa Shahvandi and Benedikt Soja, published another major study with a similar focus on climate’s impact on the Earth’s rotation. They took previous research a step further and looked 3.6 million years into the past to model and observe trends in the rate of change. Their goal? To explore how the planet’s Length of Day (LOD) has been altered since the Late Pliocene. Their findings were incredible.
Firstly, it was found that there were massive cycles of thawing and freezing of giant ice sheets that increased the LOD by up to 10 to 30 milliseconds. This is far larger than anything caused by atmospheric or oceanic processes.
But that wasn’t the most critical revelation, as they also found that Earth’s LOD was increasing at an unprecedented rate simply due to human-driven climate change, particularly ice melting. In fact, the current rate of change is among the highest seen in the past 3.6 million years.
