In a quiet, yet remarkable turn of planetary behavior, Earth is accelerating — ever so slightly. Scientists have observed that the planet is spinning faster than it has in decades, a shift that is gradually shortening the length of a day and prompting international timekeepers to consider something unprecedented: the subtraction of a second from global time.
In recent years, Earth has recorded several of its shortest days since atomic clocks began measuring time precisely. On July 26, 2022, the planet completed one full rotation in 1.50 milliseconds less than the standard 86,400 seconds — a subtle change, but one with ripple effects across science and technology.
A Spinning World in Flux
Earth’s rotation isn’t fixed. It varies constantly due to complex interactions between the planet’s core, oceans, atmosphere, and celestial mechanics. Known influences include the Chandler wobble — a small, irregular movement in Earth’s rotational axis — as well as glacial rebound, seismic activity, and even climate change, which redistributes mass on the Earth’s surface.
“There’s no single explanation,” said Dr. Leonid Zotov, a geophysicist who studies Earth’s spin dynamics. “But the combination of factors, from melting ice sheets to fluid shifts in the inner core, is causing a noticeable acceleration.”
Although Earth’s rotational speed has fluctuated throughout its 4.5-billion-year history, the recent pattern stands out. Traditionally, scientists have added “leap seconds” to keep Coordinated Universal Time (UTC) in line with Earth’s gradual slowdown. But now, the planet may be speeding up fast enough to require the first-ever negative leap second — subtracting time to catch up with the Earth.
Why Milliseconds Matter
While a millisecond-level shift may seem trivial, the implications are anything but. The modern world runs on time — from GPS satellites and aviation systems to global stock markets and the internet. These systems rely on ultra-precise atomic clocks, and even the slightest drift between Earth time and atomic time can create technical complications.
“If Earth’s rotation continues to accelerate, timekeeping authorities may have to remove a second from UTC,” explained Dr. Demetrios Matsakis, former chief time scientist at the U.S. Naval Observatory. “That’s something we’ve never done before — and we’re not entirely sure how our infrastructure would respond.”
The prospect of subtracting a second has triggered concern among engineers and programmers, who warn of potential disruptions similar to the Y2K bug or leap second glitches that previously crashed major servers.
A Global Discussion Begins
Timekeepers from the International Earth Rotation and Reference Systems Service (IERS) and the International Bureau of Weights and Measures (BIPM) are now considering whether to revise global standards to account for Earth’s quickening spin. Some argue for eliminating leap seconds altogether, as their unpredictability complicates modern computing.
Others suggest updating how time is defined, possibly breaking with centuries-old astronomical conventions.
“We’re learning that time, once thought to be immutable, is just another moving part of our living planet,” said Matsakis.
The Bigger Picture
This planetary acceleration is a reminder that Earth, while familiar, is still a dynamic celestial body. The interplay between geophysics, climate, and rotation underscores how interconnected — and fragile — our systems truly are.
Scientists emphasize that the changes are not cause for alarm, but they do reflect deeper shifts within Earth’s interior and surface. Whether due to melting glaciers, shifts in ocean mass, or variations in the planet’s core, one thing is clear: time — quite literally — is changing.
