Amidst the global challenges posed by climate change, such as the refugee crisis and more severe allergy seasons, a new concern has arisen: the potential need for a "negative leap second" to synchronize our clocks with the Earth's changing rotation.
Researchers have uncovered a complex relationship between Earth's melting ice caps and its core's shifting spin, which has a surprising impact on time.
Jacqueline McCleary, a physics professor at Northeastern University, explains this phenomenon.
"For as long as societies have existed, we've sought to track time, seasons, and days," says McCleary. "Factors like the core, crust, oceans, climate change, and glacial isostatic adjustment all contribute to Earth's changing rotation rate, which accumulates to about a second per year."
To understand this discovery, it's crucial to explore two primary timekeeping methods: Universal Coordinated Time (UTC) and International Atomic Time (TAI).
UTC, based on Earth's rotation and celestial positions, has been the global standard. However, Earth's rotation is influenced by various factors, causing it to fluctuate. This led to the development of TAI, a more precise standard.
By 1972, Earth's rotation had slowed slightly, causing UTC and TAI to diverge. To keep them synchronized, scientists introduced the leap second.
Factors such as tidal locking and glacial melt have contributed to Earth's slowing rotation. As glaciers and polar ice melt, the redistributed mass affects Earth's rotation rate, lengthening the day.
Recent discoveries indicate that Earth's rotation is now speeding up slightly. While climate change has slowed it down, the liquid core of Earth is also fluctuating, impacting the planet's surface spin.
This fluctuation could lead to a negative leap second in the future to keep atomic and astronomical time aligned, although the impacts of polar ice melt could delay this need.
McCleary warns that while our computer systems can handle positive leap seconds, they are unprepared for negative leap seconds, similar to the Y2K bug.
In conclusion, as we grapple with a changing planet, the potential need for a negative leap second highlights the impact of climate change on our world and the importance of adapting to these changes.