A new study suggests that climate change is changing the very essence of the Earth.
As polar and glacial ice melts due to global warming, water that was once concentrated at the top and bottom of the globe is being redistributed toward the equator. The extra mass at the center of the Earth slows its rotation, creating a lengthening effect on our days.
A new study provides more evidence of this dynamic, and also suggests that changes in the planet’s ice are deep enough to affect Earth’s axis—the invisible line at its center around which it spins. Together, these changes cause feedback below the surface, affecting fluids moving through Earth’s molten core.
The findings were published last week in the journals Nature Geoscience and Proceedings of the National Academy of Sciences.
The studies, along with similar research published in March, suggest that humans are tinkering with fundamental elements of the planet’s physical properties and that this process will continue until global temperatures stabilize and glaciers melt to reach equilibrium.
“You can add the Earth’s rotation to the list of things that humanity has completely influenced,” said Benedikt Soja, assistant professor of space geodesy at ETH Zurich in Switzerland and co-author of the two new studies.
The change in Earth’s rotation is significant enough that it could one day rival the effects of tidal forces caused by the Moon if carbon emissions continue at extreme levels, Soja said.
In general, the Earth’s rotation rate depends on the planet’s shape and where its mass is distributed; these factors are governed by a variety of conflicting forces.
Scientists often use the analogy of a figure skater spinning on ice: When the skaters spin with their arms outstretched, their spin will be slower. But if the skaters’ arms are held tight, they spin faster.
Similarly, the friction of ocean tides caused by the moon’s gravitational pull slows Earth’s rotation. Historically, this has had the biggest impact on the planet’s rotation rate, Soja said.
Meanwhile, the slow recovery of the Earth’s crust in some high-latitude regions following the melting of Ice Age glaciers is having the opposite effect, increasing the planet’s rotation rate.
Both processes have long had predictable effects on the Earth’s angular velocity.
But now, rapid ice melt from global warming is becoming a powerful new force. If humans continue to pollute the planet with carbon emissions, the impact of ice loss could surpass that of the moon, Soja said.
“In the worst-case scenario, yes, climate change will become the dominant factor,” he said.
A fourth important factor affecting the Earth’s rotation is the movement of liquid in its core. Scientists have long understood that this can speed up or slow down the planet’s rotation; this trend can change over 10- to 20-year intervals. Currently, the core is causing the Earth’s rotation to speed up slightly temporarily, offsetting the slowdown caused by climate change.
As a result of melting glaciers and shifts in the planet’s rotation axis, climate change also appears to be affecting the Earth’s core.
The researchers behind the new study created a 120-year model of how the polar motion, or axis, has shifted over time, and found that changes in the distribution of mass across the planet due to melting ice likely contributed to small fluctuations in polar motion.
Soja estimates that climate change is likely responsible for the 1 metre change in 10 years.
The research also suggests that the movement of molten rock within the Earth adapts to changes in its axis and rotation rate, a feedback process whereby the Earth’s surface affects its interior.
“The rotation is changing slightly, and we believe that this could have an indirect effect on the nucleus,” Soja said. “This is something that is not very easy or possible to measure directly because we can’t get down there.”
The findings have implications for how humans measure time and position satellites in space.
“For example, if you want to fly a new mission to Mars, we need to know exactly what the Earth is like in space, and if that changes, we could actually make a navigation error or a mistake,” Soja said.
For example, a 1-meter deviation in the Earth’s axis could mean that a spacecraft will miss its target by 100 or 1,000 meters when it reaches Mars.
As for measuring time, a study published in March suggested that climate change is delaying the need to add “negative leap seconds” to Coordinated Universal Time to keep world clocks in sync with the Earth’s rotation rate.
Duncan Agnew, a geophysicist at the Scripps Institution of Oceanography at the University of California, San Diego, who led the earlier study, said the new research “corresponds very well” with his own work.
“It extends the conclusion far into the future and looks at multiple climate scenarios,” Agnew said, adding that Soja and other authors reached a similar conclusion to his, though they took a different approach.
“It’s almost a rule in science to make multiple discoveries; this is another case,” Agnew said.
Thomas Herring, a professor of geophysics at the Massachusetts Institute of Technology who was not involved in either study, said the new research could provide insight into how changes at the Earth’s surface could affect what’s happening inside.
“I find this plausible for feedback between surface processes and the core,” Herring said in an email, explaining that “large-scale” processes at the surface “could permeate into the liquid core.”
This article was originally published on NBCNews.com