If the data collected can be used to build high-quality climate models of the Earth, they can be applied to the study of the ancient climate of Mars and other rocky worlds.
Scientists have long argued that periodic fluctuations in the Earth's climate are due to cyclical changes in the distribution of sunlight reaching its surface. This is due to the rotation around the axis, the ellipticity of the orbit and subtle gravitational interactions with other planets, asteroids and bodies of the solar system.
Planetary routes change over time and this can change the length of the cycles. This makes it difficult for scientists to unravel what caused many ancient climate changes. And, the further into the past, the stronger this problem.
“Tiny changes in the movement of one planet affect others. Over the millennia, these changes resonate with each other, and the entire system transforms in a way that cannot be predicted using even the most advanced mathematical calculations,”says Paul Olsen, a geologist and paleontologist at the Lamont-Doherty Earth Observatory at Columbia University (USA).
The alignment of the three planets (Jupiter, Mars, Venus) and the Moon that have the greatest impact on the Earth's orbit. The prototype of the picture was a photograph of NASA astronaut Scott Kelly, taken on October 7, 2015 from the International Space Station. Credit: Paul Olsen.
Until now, researchers were able to calculate the relative motions of the planets and their possible influence on the Earth's climate with sufficient accuracy in just 60 million years, negligible compared to 4.6 billion years of history.
However, Paul Olsen and his team have now pushed those boundaries to a record 200 million years ago. In 2018, comparing periodic changes in ancient sediments collected in Arizona and New Jersey, researchers identified a 405,000-year cycle of the Earth's orbit, which does not appear to have changed in the last 200 million years - a kind of metronome from which they can all other cycles be measured.
Using the same sediments, in a new study presented in the journal Proceedings of the National Academy of Sciences, geologists report finding an even longer climatic period of 2.4 million years, which was previously 1.75 million years.
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Geologist Paul Olsen at Arizona's Petrified Forest National Park, where 200 million stones help reveal the orbits of some of the planets in the solar system. Credit: Kevin Krajick / Earth Institute, Columbia University.
Through these two major experiments, scientists learned that changes in tropical climates from humid to dry during the time of the first dinosaurs, from about 252 to 199 million years ago, occurred in orbital cycles lasting about 20 thousand, 100 thousand and 400 thousand years, as well as a much longer cycle of 1.75 million years, which is now 2.4 million years old. According to the team, this difference is caused by the gravitational dance between Earth and Mars. “This difference is the imprint of the chaos in the solar system,” says Paul Olsen.
To test the data obtained on the influence of the Red Planet on the Earth's climate, the scientific team set out to drill samples at higher latitudes from an ancient lake beyond the Palaearctic or Antarctic circles.
If the collected data allows high-quality climate models of the Earth to be built, they can be applied to study the climate of ancient Mars and other rocky worlds. "But more exciting is the opportunity to test such conflicting theories as the possible existence of a plane of dark matter in our Galaxy, through which the solar system periodically passes," the authors of the study report.
Digital elevation map of sediments formed at the bottom of a lake about 220 million years ago near Flemington, New Jersey (USA). Credit: LIDAR image, US Geological Survey; digital colorization by Paul Olsen.
Paleoclimatic research not only reveals the past, but is also directly related to the present. While climate is highly dependent on orbit, it is also influenced by the amount of carbon dioxide in the Earth's atmosphere. We are now approaching a time when CO2 levels could be as high as they were 200 million years ago. Combining the data will give climatologists the opportunity to see the interaction of all factors, and will also help in the search for life on Mars and habitable exoplanets.
