About fifty years ago, researchers discovered that the eccentricity of the Earth was closely related to glacial cycles . In this way, during the last 400,000 years, the cycles between an ice age and an interglacial period have been synchronized with the orbit of the Earth at a speed of about 100,000 years.
It is true that it might seem surprising that such a small variation has an impact on the climate, but in reality the change in the orbit of the Earth has an influence about 10,000 times less than that of the amount of light received (which, by saying incidentally, it depends on the axis of rotation of the Earth, for example).
Hence, for years, scientists have wondered what might contribute to the amplification of these climatic fluctuations.
In a study recently published in Nature , researchers from the CNRS, in Marseille (France), analyzed phytoplankton in order to discover terrestrial climatic variations during the Pleistocene and, in particular, instead in the composition of coccoliths, which are structures limestone that cover the coccolithophore.
These structures provide a good description of the diversity of phytoplankton, since each species produces a different form of coccolith.
During the research, the scientists used artificial intelligence . And, to be precise, a powerful neural network , in order to artificially accelerate the process of formation of coccoliths. Next, they observed that the greater the eccentricity of the Earth, the more diversified the phytoplankton (and vice versa).
Not surprisingly, as indicated in their study, the more eccentric the Earth’s orbit, the greater the seasonal contrasts tend to be , which would allow increasing the number of ecological niches and, therefore, the diversity of phytoplankton.
But what the researchers especially show is that this diversity itself has an effect on climate . For example, they found that the different species of medium-sized phytoplankton, corresponding to less biodiversity, tend to store more carbon in coccoliths in the form of calcium carbon.
Specifically, the study shows what we could understand as two “peaks” of productivity: about 900,000 years ago and 400,000 years ago. That is, the phytoplankton would exert a feedback loop with the orbital cycles, amplifying the climatic variations and the carbon cycle .
Of course, the authors point out that it is quite likely that other factors influence this feedback loop.
For example, it is known that the retreat of both glaciers and islands can separate ecosystems and create more niches, accelerating the rate of phytoplankton renewal.
According to Rosalind Rickaby, a biologist at the University of Oxford, and author of an editorial that accompanies the aforementioned study, “this link between orbital change, climate and the evolution of phytoplankton could constitute an intrinsic rhythm that underlies the earth system”, which which could become an excellent example of the well-known butterfly effect .
