Mars’s gravitational pull may be strong enough to stir Earth’s oceans

An analysis of deep-sea drill cores suggests that Mars may have enough gravitational influence to shift sediment within Earth’s oceans on a 2.4-million-year cycle

By James Woodford

12 March 2024

The planets are in a gravitational dance around the sun

Shutterstock/Johan Swanepoel

The gravitational tug of Mars may be strong enough to stir up Earth’s ocean, shifting its sediments as part of a 2.4-million-year climate cycle, researchers claim.

It has long been accepted that wobbles in Earth’s orbit around the sun influence the planet’s climate, with these Milankovitch cycles operating on periods measured in thousands of years. Now, Adriana Dutkiewicz at the University of Sydney and her colleagues say they have found a 2.4-million-year “Grand Cycle”, which they believe is driven by Mars and has had dramatic impacts on currents in Earth’s oceans for at least 40 million years.

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The evidence for this cycle comes from almost 300 deep-sea drill cores that reveal unexpected variation in the deposition of ocean sediment. During periods of stable ocean currents, oceanographers expect sediment to settle in steady layers, but unusual currents and eddies can see it accumulate elsewhere.

According to the team, absences or hiatuses in the sediment deposition record line up with times when Mars’s gravity exerts maximum force on Earth, subtly impacting our planet’s orbital stability. This changes solar radiation levels and climate, manifesting as stronger currents and eddies in the oceans.

Team member Dietmar Müller, also at the University of Sydney, acknowledges that the distance between Earth and Mars is so vast that it is hard to conceive of any significant gravitational force being exerted. “But there are so many feedbacks that can amplify even subtle changes,” he says. “Mars’s impact on Earth’s climate is akin to a butterfly effect.”