Human-driven climate change is slowing Earth's rotation at a rate not seen in 3.6 million years, with sea level rise increasing the length of days by 1.33 milliseconds per century, according to a new study.

Earth spins faster when its mass is more concentrated, just as twirling figure skaters pull in their arms to speed up and spread out their arms to slow down. Rising sea levels have long been known to redistribute that mass and change the planet's spin, but the newly identified rate is unprecedented, scientists say.

Many factors influence Earth's spin speed. The moon's pull on the planet is the most significant over the long term. Its gravitational pull creates a bulge in the planet that slows Earth's rotation rate, Michael Mann, a climatologist at the University of Pennsylvania who was not involved with the new study, told Live Science. The moon's influence increases Earth's day length by about 2.4 milliseconds per century.

Although the impact would likely not be perceptible to humans, the findings have other real-world implications. For example, Mann said, instruments that require precise knowledge of Earth's rotation rate, such as those on spacecraft, may need to be recalibrated. Other precise timekeeping applications, such as in computing, could be affected, Shahvandi said.

The findings also underscore the rapidity of modern warming. "It tells us about the rapid climate change," Shahvandi said, "[the] melting of snow and ice in polar ice sheets and mountains glaciers, and increase in the sea levels."