Mars effects Our Ocean's Depths after every 2.4 Million Years

 New Study revealed that Mars tugs on Earth so hard it changes the ocean floor

A slow cosmic dance between Earth and Mars has a hidden effect on cycles in the deep ocean. A new geological study suggests that Mars' gravitational field pulls the Earth closer to the sun over cycles lasting millions of years, warming our climate. According to analysis of the deep-sea geological record, the gravitational interaction between the two planets results in cyclic changes in deep ocean currents that recur every 2.4 million years. It's a finding that will help scientists be able to better understand and predict Earth's climate going into the future.

Within cycles of millions of years, Mars pulls the Earth closer to the sun which could affect the warming of our planet via changes in ocean circulation. This Mars' gravitational pull on Earth may be influencing the climate on our planet. "We were surprised to find these 2.4-million-year cycles in our deep-sea sedimentary data," says geoscientist Adriana Dutkiewicz of 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." In recent years, scientists have started to identify what they have termed an astronomical "grand cycle". This is a 2.4 million-year pattern linked to an alignment between the orbits of Earth and Mars.

Direct evidence of this interaction in Earth's geological record is scarce, but what we have found suggests that the peak of this cycle is linked to higher solar radiation on Earth, as well as a warmer climate. This is unrelated to the anthropogenic climate change Earth is currently experiencing. Geological evidence tracing back more than 65 million years and taken from hundreds of sites across the world suggests that deep-sea currents have repeatedly gone through periods of being either stronger or weaker. This happens every 2.4 million years and is known as an "astronomical grand cycle." The stronger currents, known as "giant whirlpools" or eddies, may reach the seafloor at the deepest parts of the ocean, known as the abyss. These powerful currents then erode away at the large pieces of sediment that accumulate during calmer periods in the cycle. 

We know that other planets can influence Earth's path around the Sun, tugging it into a more elongated shape on regular cycles known as Milankovitch cycles which coincide with the rise and fall of ice ages. However, these are much more frequent (although also unrelated to anthropogenic climate change), occurring over tens of thousands of years, and they're created primarily by interactions with Jupiter and Saturn – far heftier planets than the relatively titchy Mars. These cycles happen to coincide with the timing of known gravitational interactions between Earth and Mars as the two planets orbit the sun. "The gravity fields of the planets in the solar system interfere with each other and this interaction, called a resonance, changes planetary eccentricity, a measure of how close to circular their orbits are," study co-author Dietmar Müller, a professor of geophysics at the University of Sydney, said. Milankovitch cycles were confirmed in 1976 when scientists found they had been recorded in ocean-floor sediments.

Dutkiewicz and her team were looking for something different. They were trying to determine if the currents at the bottom of the ocean change when the climate is warmer – whether they become more vigorous, or slow down. A break in sediment means faster eddies on the seafloor, while steady sediment accumulation indicates calmer conditions. Due to this resonance, the Earth is pulled slightly closer to the sun by Mars' gravitational pull, meaning our planet is exposed to more solar radiation and hence has a warmer climate, before drifting backward again — all over a period of 2.4 million years. The authors of the new study used satellite data to map the accumulation of sediment on the ocean floor over tens of millions of years. They found that there were gaps in the geological records where sediment stopped building up within these astronomical cycles. They believe that this could be linked to stronger ocean currents as a result of warmer weather caused by Mars' gravitational influence on Earth. 

They based their analysis on 293 scientific deep-sea drill holes around the world, in which they found evidence of 387 breaks in the sediment over the past 70 million years. While plotting these breaks over time, they noticed a curious clustering – the 2.4 million-year cycle that matched the astronomical grand cycles of Earth and Mars. These findings support the idea that the Red Planet influences the climate on Earth, just as passing stars and other astronomical objects have been theorized to. However, the observed warming effect is not linked to global warming that is being driven by human greenhouse gas emissions. Nevertheless, although speculative at this stage, the findings suggest that this cycle may help periodically maintain some of the ocean's deep currents in the event that global warming decreases them. 

In addition, the breaks lined up with known periods of warmer climate, including the famous Paleocene-Eocene thermal maximum which took place some 56 million years ago, when Earth's temperature rose by up to 8 degrees Celsius (14.4 degrees Fahrenheit). This event has been attributed to a number of different causes, including a glitch in Earth's orbit and a passing comet, so a potential link to Mars could be a contributing factor. It's a surprising finding, because models (and observational evidence) suggest that the circulation system responsible for the Gulf Stream could shut down as global warming melts sea ice. So scientists had thought that a warming climate would result in a deep ocean that is much less active. Now major storms become much more frequent in warmer climates, producing sediment-stirring eddies which can extend as far as the deepest abyssal depths of the ocean. This could mean that the oceans are a little bit more resilient to climate change than we thought they were.

"We know there are at least two separate mechanisms that contribute to the vigor of deep-water mixing in the oceans," Müller said. One of these mechanisms is known as the Atlantic Meridional Overturning Circulation (AMOC), Müller said. This acts as an ocean "conveyor belt," bringing warm water from the tropics to the Northern Hemisphere, pulling heat deep into the ocean in the process. Some scientists predict that the AMOC may collapse over the next few decades so it's possible that the ventilation induced by deep ocean eddies could be beneficial. "Our deep-sea data spanning 65 million years suggests that warmer oceans have more vigorous deep circulation," Adriana Dutkiewicz, lead study author and sedimentologist at the University of Sydney, said. "This will potentially keep the ocean from becoming stagnant even if Atlantic meridional overturning circulation slows or stops altogether."