Why do geologists disagree on the Anthropocene epoch? Explained by the professors of UL / Article

Earth was formed more than 4.5 billion years ago.

Associate Professor of the Department of Bedrock Geology of the University of Latvia (LU) Ģirts Stinkulis explained: “Even as a geologist with considerable experience, it seems funny to me: a million years – how can it be understood and understood? But there is enough evidence both from the remains of organisms and minerals, their age dating, which allows to prove these numbers. Basically, as in many places, this structuring is made more widely and also more and more detailed. The largest time units are eons.”

We are currently living in the Quaternary period, which began 2.58 million years ago, and – after an even more detailed division – the Holocene epoch, which began 11.7 thousand years ago. There is debate that this latest phase of geological history could be renamed the Anthropocene. The professor pointed out that the Anthropocene should not be confused with the Anthropocene, as they are “two different things”. The entire Quaternary period was once called the Anthropocene, while the “Anthropocene” refers to human influence on nature.

Evidence left by people over the past 75 years can be seen everywhere.

Professor Normunds Stivriņš of the Department of Geomorphology and Geomatics of the Lithuanian University emphasized: “A large part of the public, scientists are starting to use this term – “anthropocene”, emphasizing a set of rapid, influencing, far-reaching consequences of humans. Therefore, it is thought that a new time should be distinguished.”

Researchers consider microplastics found in sediments, radio isotopes left by atomic bomb tests and other evidence of human impact on Earth to be markers of the new era. However, human activity began long before that.

“The new geographical discoveries when Europeans went to the Americas; millions of people died out, so there were no more people to work the agricultural land – overgrown with forests. Removed CO from the atmosphere₂ more, and released more oxygen, and this affects the climate. There are many such factors, so there is controversy and no consensus [vienprātības – red.] about this issue,” admitted Stivriņš.

In order to carve out a new distinct time period, there must be clear consequences and evidence that can be seen all over the world. There is data on fossils, there is data on mineral ages, and we can trace these layers, but in the case of microplastics, we can unwittingly mislead future generations of researchers.

“This plastic migrates in deeper layers, so it can be found at different depths, and we cannot say – this is where microplastic or plastic started in sediments, and this is the time when man lived. Because plastic extends much deeper than we expected,” Stivrins explained.

Human impact in space and nuclear weapons

Some researchers believe that the Anthropocene began in 1950. However, human influence can also be observed far away from Earth – in space. Raitis Misa, an astronomy enthusiast and representative of the editorial board of the “Starry Sky” magazine, stated that October 4, 1957, when the first artificial satellite of the earth was launched, could be considered the beginning of human influence outside the earth’s atmosphere.

“Currently, there are thousands of man-made objects, satellites and things that are no longer used – the so-called space debris – in the earth’s orbit. And, of course, there are also a lot of objects located on other celestial bodies – on the Moon, on Mars, on Venus and there are still traces of man here and there. If an extraterrestrial archaeologist were to look, they would surely find and realize that this is not a natural object,” Misa said.

Space debris closer to Earth orbit will burn up, but it may take 100 or even 1,000 years, and in space exploration the debris we create and leave behind will cause more and more problems.

However, Misa believes that this is not a reason to single out a new geological time scale: “The activities of space exploration are not so pronounced and have such a significant impact. On the other hand, the use of nuclear weapons or plastic – this could serve as some kind of starting point for changes in the earth’s geology in general.”

The beginning of the era of nuclear weapons is 1945. The number of tests exceeds 2000 – both surface and underground. Nuclear weapons have been used twice, when the USA used them against Japan, and more than 200 thousand people died, including the effects of radiation, because after the nuclear combustion reaction, uranium-235 and plutonium-238 split into lighter elements that are still radioactive for a long time. It is quite clear that it has had a significant impact on nature.

Man as an event in the history of the earth

One of the reasons why the decision to distinguish the Anthropocene as a separate era has not been made – researchers believe that a new stage in geology must be radically different from the previous one and must exist for a long time, millions of years.

“And the point being made about human impact, we don’t know when it’s really going to end and whether it’s just an event because we don’t know if humanity is going to be around. We may still be living in the Holocene, and the Holocene will continue when it comes, maybe , the new ice age. Will something else happen, or will the environment change. And man may have already ceased to exist, and from that point of view – philosophically – we are like an event in the history of the earth,” concluded Stivriņš.

It is to be hoped that future generations will live with less damage to the environment, but our “fingerprints” will not disappear anywhere.

“For example, in the oceans, a layer of sediment less than a millimeter thick will probably form in 100 years. But in peat bogs, for example, the peat regenerates at an average rate of 1-3 millimeters per year, so there could even be 10-30 centimeters of sediment in 100 years. Sediment also accumulates in lakes. For example, in such a swamp environment, you can very well recognize everything that has come from the air and, to some extent, from the waters, and find out what kind of impression a person has left. In principle, everything is preserved everywhere,” explained Stinkulis.

On the one hand, people should not overestimate themselves, because we are nothing so unique in the history of the Earth, but on the other hand, it is our duty not to destroy the Earth beyond recognition.

“The conditions are fantastic for us to be able to live here. We have a sufficient concentration of atmospheric gases so that we can breathe. There are no more dinosaurs, there are no more others that we have to compete with, that would have already condemned us in their lunch,” emphasized Stivriņš. “And here come again these natural disasters, which repeat themselves cyclically from time to time. They, so to speak, erase all the previous ones – not all, but a large part – and give room for new development…”

Usually, an interglacial lasts for 10-15 thousand years. This means that, in theory, there could be another 3,000 years of this warm weather. But predictions are also made that the next ice age has moved away by several tens of thousands of years, but theoretically the ice age can also come much faster. Predicting the future is difficult.

“Natural disasters are what we can’t really prepare for – earthquakes, tsunamis, volcanic eruptions. There’s also the North Atlantic Current – the Gulf Stream, which is why we can live so far north in these latitudes. And what’s being observed now that this Gulf stream is slowing down, the heat is not transferred to the European part, therefore so much,” Stivriņš explained.

Several models predict cooling for Northern Europe, while others predict direct warming. Volcanic eruptions also complicate calculations.

“Models are good tools, but it just shows that we don’t really have clear mechanisms of how nature works in general. So we can’t predict what these end effects will be. And if more volcanic eruptions come, it just complicates the calculations, ” admitted the professor.

In March, the international meeting of geologists rejected the idea of ​​distinguishing the Anthropocene, so no new time scale has been distinguished, but at the same time, the term for human-made influence will be heard more and more often in society and humanities.