- The gravitational pull Mars exerts on Earth may be strong enough to impact ocean currents.
- The red planet can cause deep-sea currents to change over a 2.4 million-year cycle, a study said.
- The study could help scientists create better climate models of Earth.
Mars may be 140 million miles away, but its gravitational pull could be impacting Earth's oceans.
Scientists at the University of Sydney in Australia believe the red planet's tug is creating "giant whirlpools" in the oceans called eddies, which can shift the deep-sea floor.
This, they claim, is part of a 2.4-million-year climate "grand cycle" on Earth that has been ongoing for at least 40 million years.
"We were surprised to find these 2.4-million-year cycles in our deep-sea sedimentary data," said Adriana Dutkiewicz, a geosciences researcher at the University of Sydney
"There is only one way to explain them: they are linked to cycles in the interactions of Mars and Earth orbiting the sun."
Tiny changes can have huge effects
If the climate crisis has taught us one thing, it's that seemingly insignificant events — such as humans picking carbon-based fuels to power their industry — can unleash catastrophic impacts on our delicately balanced climate down the line.
How humans are causing the rapid warming of the planet today is very clear.
But what scientists are increasingly figuring out is how even smaller changes to the planet, like tweaks to its position in the solar system, can influence long-term trends in the climate.
Previous studies have suggested that tiny wobbles of our Earth's axis can tip the scales for the climate on the scale of tens of thousands of years.
Now, scientists are proposing an "astronomical grand cycle" on the scale of millions of years, which they say is caused by the subtle effect of Mars's gravitational pull.
"Mars's impact on Earth's climate is akin to a butterfly effect," said study author Dietmar Müller, a professor of geosciences at the University of Sydney, to New Scientist.
Earth resonates with Mars, and that slowly shifts the climate and oceans
The evidence for this theory lies in almost 300 cores deep-sea cores tracking ocean sediments back more than 65 million years.
These revealed that sediment deposits follow a very long period, ebbing and flowing every 2.4 million years.
This suggests something weird is happening on that time scale, which lines up suspiciously with periods of a warmer climate, Müller, Dutkiewicz, and their co-author said in a study published Tuesday.
For the scientists, there's one culprit: Mars.
The red planet's orbit and ours are locked in an intricate dance, and every so often, these line up so that Mars' gravitational pull on Earth is just a little more intense — this is called resonance.
This, in turn, could pull Earth ever so slightly toward the sun, increasing the surface temperature and solar radiation.
That can have a knock-on effect on the climate through the seas. Oceans are known to create giant whirlpools ahead of warming climates.
This effect wouldn't upheave the climate on its own, but it could nudge our planet toward a slightly warmer system by tweaking the Atlantic current that regulates the Gulf Stream, for instance.
The findings were published in the peer-reviewed journal Nature Communications.
More evidence is needed
Not everybody agrees that the case is closed on these million-year variations.
Matthew England at the University of New South Wales in Sydney, told New Scientist he was "skeptical" given Mars's weak gravitational pull.
"Even Jupiter has a stronger gravitational field for Earth," he said.
Still, if correct, this theory would add precious understanding to these "megacycles." This information is crucial when refining models helping us see how our planet's intricate climate will progress over time.
"Many of us have seen these multi-million-year cycles in various different geological, geochemical and biological records — including during the famous explosion of animal life in the Cambrian Period," Benjamin Mills a biogeochemist at the University of Leeds who wasn't involved in the study told New Scientist.
"This paper helps cement these ideas as key parts of environmental change," said Mills.