Mars Has an Unexpected Influence on Earth’s Oceans and Climate, Repeating Every 2.4 Million Years, Study Finds

In an astonishing cosmic cycle that occurs every 2.4 million years, Mars’ gravitational pull is shifting Earth’s path around the sun, warming its climate and increasing vigorous deep ocean circulation, according to a new study published this week in the journal Nature Communications.

“Mars’ impact on Earth’s climate is akin to a butterfly effect,” study co-author Dietmar Müller, a geophysicist at the University of Sydney in Australia, tells New Scientist’s James Woodford. He acknowledges the Red Planet is too far to have an immense gravitational impact on our world. “But there are so many feedbacks that can amplify even subtle changes.”

By poring through 65 million years of deep-sea sediment records, researchers analyzed Earth’s history of ocean current behavior. They sampled nearly 300 drill cores, which documented how these currents behaved over time. Breaks in sedimentation indicated the presence of vigorous deep-sea currents, while continuous sedimentation represented calmer conditions.

The team found the strength of these currents waxed and waned over 2.4-million-year cycles, known as “astronomical grand cycles.” Comparing this fluctuation to astronomical events, researchers found an unexpected connection: Each cycle coincided with records of gravitational interactions between Earth and Mars.

“We were surprised to find these 2.4-million-year cycles in our deep-sea sedimentary data,” says Adriana Dutkiewicz, lead author of the study and sedimentologist at the University of Sydney, in a statement. “There is only one way to explain them: They are linked to cycles in the interactions of Mars and Earth orbiting the sun.”

As the two planets chart their orbital paths, their gravitational fields interact in a process called resonance, Müller says in the statement. This cosmic exchange alters how circular Earth’s orbit around the sun is—and consequently, how close the planet is to solar energy. During periods with greater exposure to solar radiation, the Earth adopts a warmer climate. And with this warmer climate, the amount of vigorous ocean currents was found to increase.

Researchers describe the currents, also called eddies, as “giant whirlpools” that often stretch down to the abyssal seafloor and erode the area, driving the accumulation of large amounts of sediment in snowdrift-like walls.

These natural, gravitationally induced climate cycles are not tied to the current and rapid global warming, which is a product of excessive greenhouse gas emissions. However, studying the eddies’ response to warmer climates across long periods of time can provide scientists with crucial insight into how climate change affects ocean circulation.

If human-produced global warming continues along its current path, “this effect will dwarf all other processes for a long time to come,” Muller tells CNN’s Laura Paddison. “But the geographical record still provides us with valuable insights about how the oceans operate in a warmer world.”

With climate change, scientists have suggested a vital ocean current system called the Atlantic Meridional Overturning Circulation (AMOC)—which transports warm water north and cold water south—could soon collapse. A study last year found the system will likely shut down sometime this century—and as soon as 2025.

The new research indicates the cosmic cycle that drives deep ocean eddies could help bolster ocean circulation in the event of an AMOC collapse.

“We know there are at least two separate mechanisms that contribute to the vigor of deep-water mixing in the oceans. AMOC is one of them, but deep ocean eddies seem to play an important role in warm climates for keeping the ocean ventilated,” says Müller in the statement.

Still, some scientists remain unconvinced by certain aspects of the research. Matthew England, who studies ocean circulation at the University of New South Wales in Australia and was not involved in the study, tells New Scientist he isn’t sure the Red Planet is to blame for these cycles.

“I’m skeptical of the link to Mars, given its gravitational pull on Earth is so weak—at only about one one-millionth of that of the sun,” he tells the publication. “Even Jupiter has a stronger gravitational field for Earth.”

Joel Hirschi, associated head of marine systems modeling at the National Oceanography Center in England who was not involved in the study, tells CNN that the findings in relation to Mars’ influence on ocean currents were significant. But, he adds that the “proposed link with the ocean circulation is speculative.” Though eddies have grown in activity over the past decades, satellite observations have shown their currents aren’t always able to reach the seafloor and maintain effective ventilation, he tells the publication.

Still, researchers remain hopeful that the 2.4-million-year cycle, and the increased circulation it may regulate, could provide a necessary fallback for ocean systems in the climate crisis.

“Our deep-sea data spanning 65 million years suggests that warmer oceans have more vigorous deep circulation,” adds Dutkiewicz in the statement. “This will potentially keep the ocean from becoming stagnant, even if Atlantic Meridional Overturning Circulation slows or stops altogether.”

Catherine Duncan | READ MORE

Catherine Duncan is an intern with Smithsonian magazine.