Milankovic’s cycles are not responsible for the fact that our planet is getting hotter

Fake News Tragač

Original article (in Serbian) was published on 04/08/2023; Author: Ivan Subotić

What unites Gavrilo Princip and Milutin Milankovic? Serbian origin, some would say. A vision, others might say. “Pecat”, we add, in case you missed the mental acrobatics from one of the recent covers of this paper.

In the edition from June 16, while answering the question “What connects them?”, this paper published the following:  “Our scientist Milutin Milankovic could therefore have the same effect on the geopolitical strategy of ‘climate change’ as Gavrilo Princip had on the Austro-Hungarian Empire”.

Pecat’s unusual pairing of famous Serbian personalities is based on disinformation that Milankovic’s cycles are proof that the warming we are witnessing is a natural phenomenon and that human influence on climate change is negligible.

The text about the connection between current climate changes and Milankovic’s cycles was written for Pecat by Nebojsa Radic, a correspondent of this paper from Cambridge. By the way, Radic earned a doctorate in creative writing in Great Britain, and a master’s degree in teaching with technology in Vancouver and Italian language in New Zealand. He currently works as the director of the language program at the University of Cambridge.

What are “Milankovic’s cycles”?

About a hundred years ago, Milankovic made a great contribution to science by helping us to understand how the change in the position of the Earth in relation to the Sun affects long-term climate changes on our planet. These changes in the position of the Earth affect – among other things – ice ages, and they were named Milankovic’s cycles. Specifically, Milankovic based his theory on three changes. Here we will also provide rough estimates of their duration, while the oscillations that occur in this regard should also be taken into account.

  1. Change in the shape of the Earth’s orbit (eccentricity): a cycle that spans about 100,000 years and involves a change in the form of the Earth’s orbit from approximately circular to slightly elliptical. This change occurs primarily under the influence of the gravitational forces of the two largest planets of the Solar System – Jupiter and Saturn.
  2. The change in the tilt of the Earth’s rotation axis during its orbit around the Sun: a cycle that spans about 41,000 years and implies a change in the tilt of the Earth in its orbit around the Sun, which affects the change in intensity of the seasons.
  3. Change in the position of the Earth’s axis (precession): a cycle that spans about 23,000 years and involves the ternary “swaying” of the Earth’s axis, which is a consequence of the gravitational influence of the Sun and the Moon.

All these changes affect the amount of solar radiation that reaches the top of the atmosphere, as well as the range of radiation. The climate does indeed change under the influence of these changes, but in extremely long periods: changes based on Milankovic’s cycles occur over tens or even hundreds of thousands of years.

How did Pecat present Milankovic’s cycles?

In just a few sentences, Pecat’s correspondent explains that Milankovic “studied the documentation on climate change” and “noticed that changes occur over time”.

“His explanation for these changes was that the Earth’s orbit around the Sun is irregular, elliptical, so that sometimes our planet is further away and sometimes closer to the Sun. Such minor changes occur approximately every 22,000 years, and larger oscillations in this orbit occur every 100,000 years. He also calculated that every 41,000 years the Earth tilts to one side or the other, so that it moves the frozen poles closer or further away from the Sun”, writes Radic.

It can be concluded from these statements that the author confuses the change in the shape of the Earth’s orbit and the change in the position of the Earth’s axis, explaining the first phenomenon as a major change in the Earth’s orbit, and the second as a minor one. However, as we have already stated, Milankovic’s cycle of about 100,000 years refers to the Earth’s orbit, while the cycle of about 23,000 years refers to the change in the position of the Earth’s axis, not its orbit.

At the end of his presentation of Milankovic’s cycles, the author makes another assessment: “Milankovic worked a century ago and stated that at that moment the planet Earth has been approaching the Sun for a hundred years, which causes warming. If we add another hundred years, we arrive at the mentioned UN figure of two hundred years”.

Here, Pecat’s correspondent tries to make a connection between Milankovic’s cycles and the assessment of the United Nations and numerous climate change experts suggesting that global warming is connected to the industrial revolution that began about 200 years ago. However, as experts from NASA explain, the Earth is currently in an interglacial period (a period of mild climate between two ice ages), which means that it should be gradually cooling, not warming, if we were to follow Milankovic’s theory.

Does the climate crisis we are facing have anything to do with Milankovic’s cycles?

In short – no. The thesis about the connection between Milankovic’s cycles and global warming has been spreading on the Internet for years. Numerous media that deal with data verification reacted to such claims, including Snopes, Logically Facts, as well as our partner web portal from Croatia, Faktograf. The news agencies Reuters, AFP and AP, and even the American space agency NASA, wrote that Milankovic’s cycles cannot explain the current global warming.

In the podcast of the web portal Klima101, dedicated to misconceptions about climate change, meteorologist and professor of the Faculty of Physics in Belgrade, Vladimir Djurdjevic, explains that it would be nice if Milankovic’s cycles could save us from climate change or that they are the cause of it, but that – unfortunately – this is not the case.

“Milankovic’s cycles take place on very long time scales. You have to wait several thousand or 10,000 years to see some change that introduces you to the ice age or returns you from the ice age to the interglacial. When we talk about current climate changes, things happen on much shorter time scales. They happen on a scale of several decades. From the moment I was born until today, the temperature has risen close to one degree. When we talk about Milankovic’s cycles, even if I were the pyramid of Cheops, I probably wouldn’t notice anything in terms of climate”, says Djurdjevic.

FN Tragac also discussed the alleged connection between Milankovic’s cycles and current climate changes with climate change expert Danijela Bozinovic, who explains that the characteristics of climate conditions on Earth are influenced, among other things, by changes in the position of the Earth in relation to the Sun, which Milankovic’s theory deals with. However, she also draws attention to the fact that “these changes are not significant on smaller time scales and cannot be felt during a person’s lifetime, or even during the lifetime of ten or more generations”.