Mars may be around 240 million miles from Earth, but the red planet affects our deep oceans by helping to move “giant eddies”, according to new research.
To better understand the power of deep ocean currents, scientists analyzed sediments excavated from hundreds of deep-sea sites over the past half-century to peer into tens of millions of years of Earth’s history.
What they found surprised them.
The sediments revealed that deep-sea currents weakened and strengthened over a 2.4-million-year climate cycle, according to the study published Tuesday in the journal Nature Communications.
Study co-author Adriana Dutkiewicz, a sedimentologist at the University of Sydney, said scientists did not expect to discover these cycles and that there was only one way to explain them: “They are linked to cycles in Mars’ interactions.” and the Earth’s rotation around the Sun,” he said. The authors say this is the first study to establish these connections.
Two planets influence each other through a phenomenon called “resonance”; it is a gravitational push and pull between two orbiting bodies on each other; It is sometimes described as a kind of harmony between distant planets. This interaction changes the shape of their orbits, affecting how close they are to the circle and their distance from the sun.
For Earth, this interaction with Mars means periods of increased solar energy (meaning a warmer climate), and these warmer cycles are associated with stronger ocean currents, the report found.
Geophysics professor Dietmar Müller said that although these 2.4-million-year cycles influence Earth warming and ocean currents, they are natural climate cycles and are not linked to the rapid warming the world is experiencing today as humans continue to burn planet-warming fossil fuels. at the University of Sydney and co-authored a study.
The authors describe these currents, or eddies, as “giant eddies” that can reach the bottom of the deep ocean, eroding the seafloor and causing large accumulations of sediment such as snowdrifts.
Scientists were able to map these powerful eddies through “breaks” in the sediment cores they analyzed. Deep-sea sediments form in continuous layers during calm conditions, but strong ocean currents disrupt this, leaving a visible trace of their presence.
Because satellite data that can visibly map changes in ocean circulation has only been available for a few decades, sediment cores that help build a picture of the past going back millions of years are very useful for understanding circulation changes in a warmer climate. Müller told CNN.
If today’s human-induced warming continues on its current course, Müller said: “This effect will dwarf all other processes for a long time.” “But the geological record still provides us with valuable information about how the oceans functioned in a warmer world.”
The authors suggest that these eddies may even help mitigate some of the effects of the potential collapse of the Atlantic Meridional Overturning Circulation (AMOC), a key ocean circulation that operates like a giant conveyor belt carrying warm water from the tropics to the oceans. far North Atlantic.
Scientists are increasingly sounding the alarm about the health of this critical current system. As global warming warms oceans and melts ice, disrupting the delicate balance of heat and salt that determines the AMOC’s strength, there are fears it could even give early signs of collapse.
A collapse would have catastrophic consequences for the climate, including temperatures falling rapidly in some places and rising in others.
“Our study says nothing about what may or may not happen to AMOC,” Müller said. “What we’re saying is that even if the AMOC shuts down, there are other processes that will stir up the ocean, even if their effects are quite different.”
There are fears that shutting down the AMOC will mean that oxygen-rich surface waters will no longer mix with deeper water, leading to a stagnant ocean largely devoid of life. “Our results suggest that more intense deep ocean eddies in a warmer world could prevent such ocean recession,” he said.
Joel Hirschi, deputy head of marine systems modeling at the National Oceanography Center in the United Kingdom, who was not involved in the research, said the study’s finding of the existence of a 2.4-million-year cycle in marine sediments was remarkable. He added that the methodology was sound and a connection with Mars was possible.
But “the proposed link to ocean circulation is speculative, and the evidence that deep ocean circulation associated with eddies is stronger in warm climates is weak,” he told CNN.
Satellite observations have shown that these eddies have become more active in recent years, but the currents do not always reach the ocean bottom, meaning they cannot prevent sediment buildup, he said.
The authors of the study said in a statement that it remains unclear exactly how the different processes affecting deep ocean currents and marine life will work in the future, but they hope this new study will help better model future climate outcomes.
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