Scientists Describe What Would Happen if Earth’s Rotation Accelerated — and Why a Catastrophic Speed‑up Is Implausible

Scientists say a sustained, dramatic increase in Earth’s rotation would reshape oceans, amplify tides and storms, and raise geological stress — but they emphasize that the kind of runaway acceleration depicted in recent fiction is not supported by real‑world physics.

Measurements from atomic clocks show that the length of Earth’s solar day is not perfectly constant and can vary by a few milliseconds. The fastest day recorded to date occurred on July 5, 2024, when Earth completed a rotation 1.66 milliseconds shorter than the standard 24‑hour day. Scientists also reported days between 1.3 and 1.51 milliseconds shorter on July 9, July 22 and Aug. 5 this year. Researchers attribute such tiny fluctuations to a mix of factors, including changes in the atmosphere, seasonal redistribution of water from melting glaciers, motion in the planet’s molten core and variations in ocean and wind patterns.

But even small, measurable speedups are far removed from scenarios in which a day shrinks from 24 hours to a few hours or less. In the novel Circular Motion, by Alex Foster, a network of high‑altitude aircraft allegedly accelerates Earth’s spin until a day lasts two hours, triggering widespread catastrophe. Geophysicists and astronomers who reviewed that premise for news outlets described the plot as fictional and physically implausible.

If Earth’s rotation were to increase substantially, experts say the most immediate large‑scale effect would be a stronger centrifugal force at the equator, producing a more pronounced equatorial bulge. "The largest changes would be in the ocean tides," said Duncan Agnew, a professor of geophysics at the University of California, San Diego. Water currently concentrated at the poles would migrate toward the equator, making equatorial regions relatively more inundated and polar seas shallower. That redistribution could leave some low‑latitude land permanently or periodically under water and increase the risk of tsunamis and coastal flooding.

A faster rotation also would alter tidal timing and amplitude because the regular pattern of two high and two low tides per 24 hours and 50 minutes depends on the interplay between Earth's spin and the gravitational pulls of the moon and sun. "Change that by 10 percent and the tides in some places would get larger and in others smaller," Agnew said, describing how localized tidal impacts would vary with coastline geometry.

Seismically, an accelerated spin would affect tectonic stresses. Agnew said increased rotation would tend to speed plate motions and could add to geological stress, producing more earthquakes. The shifting distribution of mass — from polar ice and oceans toward the equator — would also alter stress on the crust and mantle in complex ways.

Atmospheric and storm systems would respond to a changing rotation rate through the Coriolis effect, which influences the spin and path of large weather systems. "Hurricanes will spin faster and carry more energy," said NASA astronomer Sten Odenwald, warning that intensified storm rotation would increase destructive potential in sensitive regions.

Human systems would face additional disruption. Faster days would shorten daylight periods and could interfere with circadian rhythms that evolved for roughly 24‑hour cycles, with consequences for sleep, productivity and health. Satellites and other space infrastructure depend on predictable rotational timing; significant changes could misalign satellite orbits and ground tracking, disrupting communications, navigation and broadcasting.

Several factors make a dramatic, rapid spin‑up of the planet highly unlikely, scientists stress. Earth’s rotation has been slowing over geologic time due largely to tidal friction with the moon. Over billions of years the length of the day has increased; estimates place the early Earth’s day at a few hours immediately after formation, and perhaps about 19 hours a billion years ago. "In actual fact, the Earth has been rotating more and more slowly over the long term," Agnew said.

Conservation of angular momentum imposes strict constraints on how Earth’s spin can change. Dr. Judah Levine, a fellow at the U.S. National Institute of Standards and Technology, pointed out that any substantial increase in Earth’s rotation would require a corresponding loss of angular momentum elsewhere in the Earth–moon–solar system system, such as a dramatic alteration in the moon’s orbit. If the moon were to transfer angular momentum to Earth, the moon would move closer and tidal effects would grow far stronger and more frequent — itself a catastrophic outcome. A direct impact by a massive body striking Earth at the precise angle and speed needed to speed the rotation would likely vaporize or at least liquefy the crust and mantle, eliminating any possibility of human survival long before new, shorter days became established.

Scientists are continuing to study the small day‑to‑day and year‑to‑year variations that are routinely recorded by atomic clocks and by astronomical observations. Researchers are examining the combined roles of atmospheric circulation, ocean currents, melting glaciers, core motion and interactions with the moon to understand short‑term jitter in Earth’s rotational rate. While unusual weather patterns such as El Niño and rapid summer glacier melt can produce measurable but minute changes in rotation, none of those mechanisms produce the runaway acceleration described in fictional accounts.

The measured millisecond variations are important for precision timekeeping, satellite navigation and geophysical research, and they prompt continued monitoring and study. But leading scientists say the physics governing planetary rotation and angular momentum make an abrupt, civilization‑ending speed‑up effectively impossible under known natural processes.

"This cannot happen and nothing like it has ever been observed for any planet or star," Agnew told reporters, summarizing the consensus view that the dramatic scenarios remain in the realm of speculative fiction rather than near‑term reality. Researchers continue to refine measurements and models to understand small fluctuations and their links to climate and interior dynamics, while underscoring the very different scales between millisecond variations and the catastrophic changes portrayed in some popular narratives.