In the foreseeable future, a moment in time will be lost worldwide. This unprecedented event is being shaped by human actions, as a recent study reveals that the melting of polar ice caps is modifying Earth’s rotation and, in turn, altering time itself.
Our daily schedules are governed by the rotation of the Earth. However, this rotation isn’t fixed; it can subtly fluctuate based on activities on the Earth’s crust and within its fiery core.
These minute alterations occasionally necessitate an adjustment to global clocks by a “leap second.” While this may seem insignificant, it can significantly impact digital systems.
Over time, numerous seconds have been appended. But following a prolonged period of deceleration, Earth’s rotation is now accelerating. For the first time in history, a second will need to be subtracted.
“An inverse leap second has never been implemented or tested, so the potential issues it could pose are unparalleled,” stated Patrizia Tavella, a Time Department member at the International Bureau of Weights and Measures in France, in an article accompanying the study.
The timing of this event is being swayed by climate change, according to the study published in the journal Nature. The melting of polar ice is reducing the effect on Earth’s rotation and has postponed the date by three years, shifting it from 2026 to 2029, the report discovered.
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Flowing water from melting ice in Scoresby Fjord, Greenland, in August 12, 2023. |
“Understanding the implications of climate change is crucial to predicting future global timekeeping events,” said Duncan Agnew, a geophysics professor at the University of California San Diego and the author of the study.
Before 1955, a second was defined as a specific fraction of the time it took for the Earth to complete one rotation relative to the stars. The advent of highly precise atomic clocks ushered in a more stable method of defining a physical second.
From the late 1960s, the world began using coordinated universal time (UTC) to establish time zones. UTC depends on atomic clocks but still synchronizes with the planet’s rotation.
However, as the rotation speed varies, the two timescales gradually diverge. This necessitates the occasional addition of a “leap second” to realign them.
Long-term changes in Earth’s rotation have been primarily influenced by the friction of tides on the ocean floor, which has decelerated its rotation. Recently, the effects of melting polar ice, caused by humans burning fossil fuels that heat the planet, have become a significant factor, Agnew noted. As the ice melts into the ocean, the meltwater migrates from the poles toward the equator, further decelerating the Earth’s rotation speed.
Ted Scambos, a glaciologist at the University of Colorado Boulder who was not involved in the study, likens the process to a figure skater spinning with their arms overhead. As they lower their arms toward their shoulders, their spin decelerates.
The melting of polar ice “has been substantial enough to noticeably affect the rotation of the entire Earth in a way that is unprecedented,” Agnew stated. “To me, the fact that human beings have caused the Earth’s rotation to alter is quite astonishing.”
While melting ice may be decelerating the Earth’s spin, another factor is influencing global timekeeping, according to the report: processes in the Earth’s core.
The planet’s liquid core rotates independently of its solid outer shell. If the core decelerates, the solid shell accelerates to conserve momentum, Agnew explained, and that is what’s currently transpiring.
Source : CNN
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