Why divide the Anthropocene?
The “Anthropocene Working Group” believes that the “Anthropocene” has arrived and plans to submit a formal proposal to the International Stratigraphic Commission in 2021. What is the “Anthropocene”?
The earth has gone through five great time scales: Archean, Proterozoic, Paleozoic, Mesozoic, and Cenozoic. These five great time scales have witnessed the earth-shaking evolution of geological structure and the evolution of species. Now we are in the seventh generation of the Cenozoic—the Holocene. . The Holocene began at the end of the last ice age on the earth. With the retreat of large-scale glaciers, the earth became warmer and wetter. Human agriculture began to multiply and grow. To this day, the Holocene has been 12,000 years old.
However, since modern times, human beings have become stronger and stronger, and they have begun to have a non-negligible impact on the earth. As early as the middle of the 19th century, scholars began to think about this kind of impact of humans on the earth and regarded human activities as a kind of Special geological action. This influence has only increased in modern times, so some people began to think whether we have entered a new era? So the concept of the Anthropocene began to appear.
In 2000, at an academic seminar held in Mexico, the concept of the Anthropocene attracted attention for the first time. At that time, Nobel Prize winner and Dutch atmospheric chemist Paul Kruzen believed that we are no longer in the Holocene, but in the Anthropocene.
Since then, this idea spread quickly and attracted the attention of scholars in different fields. In 2009, the International Commission on Stratigraphy established the “Anthropocene Working Group” and formally began to study the feasibility of the Anthropocene as a new chronostratigraphic unit.
In 2016, the working group found multiple evidences in the sediments of Bingxin, rivers and seas, proving that since the middle of the 20th century, the earth has entered a completely different era from the Holocene.
On May 21, 2019, 34 members of the Anthropocene Working Group initiated a vote and decided to formally submit an application to the International Geosciences Union for “joining the Anthropocene on the Representative of Geological Years” and set the beginning of the Anthropocene at In the middle of the 20th century, it finally won 29 votes in favor.
Why divide the Anthropocene?
In the history of the earth, the dinosaurs, the behemoths we know and once rulers of the earth, completely withdrew from the stage of history because of the collapse of the global ecosystem caused by the impact of asteroids on the earth. What followed was the decline of reptiles and gymnosperms, as well as the rise of mammals and angiosperms. The earth’s topography has undergone completely different changes. Geologists classified this period as the end of the Mesozoic and the beginning of the Cenozoic. The earth entered the Paleogene from the Cretaceous.
Just like dividing the 4.5 billion-year-old earth into several stages according to different characteristics, it is very necessary to divide the Anthropocene to study and understand the earth. Although the difference between the Anthropocene and the Holocene is not as significant as the previous historical period, it is still sufficient to meet the criteria for dividing the new geological era.
The standard for dividing the Anthropocene is based on changes in the earth’s environment and this change is caused by humans. So what impact did humans have on the earth?
As early as 8,000 years ago, humans started agricultural activities, burning forests and planting plants, which increased the carbon dioxide and methane content in the atmosphere. Some scholars believe that humans began to have an impact on the ecology of the earth during this period, so the Anthropocene should start from this time. This idea is of course undesirable, because although early agricultural activities did have an impact on nature, the impact was minimal and left no corresponding traces. At that time, the changes in the atmosphere were probably just the fluctuations of the atmosphere itself, not by humans.
After the British Industrial Revolution in the 18th century, large-scale industrial production burned a large amount of coal, resulting in a significant increase in the carbon dioxide content in the atmosphere, which exceeded the natural fluctuation range. Therefore, there is a view that this period should be used as the starting point of the Anthropocene. However, the industrial revolution only changed the composition of the atmosphere and did not bring about global changes in other aspects of the earth, so this view is also untenable.
Since the end of the Second World War, human society has developed rapidly in an all-round way, the population has doubled, and fossil fuels have been consumed in large quantities. The ability of humans to transform nature has been different from the past. The impact of human activities on nature has expanded to the entire earth. It is changing this planet at an unprecedented speed, surpassing the power of nature itself, and becoming the first factor that dominates the earth’s environment. Therefore, it is scientific and reasonable to regard the 1950s as the starting point of the Anthropocene.
Since its birth, the earth has undergone 4.6 billion years of magnificent vicissitudes of vicissitudes. Life has been endless and reincarnated in several epochs. Recently, “Nature” magazine reported that the authoritative scientific research group “Anthropocene Working Group” passed a vote and recognized that mankind has officially entered a new geological era-the Anthropocene!
What changes has the earth entered into the Anthropocene?
With the big explosion of science and technology and the advancement of globalization, human behavior has affected every corner of the world, but the Anthropocene is a geological age, and geologists not only consider “influence” and “change” in classifying a new geological age. It is mainly based on the changes of the strata. This change must be very obvious and can form a permanent mark, which can be used as a reference for later generations. Therefore, geologists have selected several typical geological features as the basis for the existence of the Anthropocene.
The first is the sediment from a nuclear explosion. On July 16, 1945, the first nuclear test in human history conducted by the United States in New Mexico marked the beginning of the nuclear age.
For geologists, nuclear explosions have also formed a comparable chronological layer on a global scale. Because the power of the atomic bomb comes from the energy generated by the instantaneous fission of two radioactive isotopes of uranium-235 and plutonium-239. After a nuclear explosion, these isotopes and their products are also carried into the atmosphere, and reach all parts of the world with the atmospheric circulation and are deposited. Therefore, deposits containing nuclear explosion products can be found in the sediments of lakes, glaciers and oceans all over the world. Moreover, a substance like uranium-235 has a very long half-life, about 700 million years, which can be discovered by later generations a long time later.
The second is that chemical fertilizers such as nitrogen and phosphate fertilizers used by humans in agricultural production have left obvious records in the soil layer and water bodies, changing the characteristics of rivers, oceans and other water sediments, making nitrogen and phosphorus in soil and water sediments. Significant changes have taken place in other elements, causing the largest nitrogen cycle change on the earth in 2.5 billion years.
The third characteristic is brought about by human life equipment. Man-made objects such as plastics and buildings are almost everywhere in the world. Among them, plastic has entered every corner of the earth along with human activities or water cycles. From the depths of the oceans to polar glaciers, there are shadows of plastic, which will surely leave obvious geological records.
The fourth characteristic is created by humans’ extensive use of fossil fuels. After the Industrial Revolution, coal became the main fuel for industrial production; after World War II, oil became an indispensable blood for Ding Ye. If fossil fuels are not fully burned, carbon will be produced and emitted into the air. As the air circulates around the world, it will be deposited and become an obvious layer of black carbon. There is also the emission of greenhouse gases, which is carbon dioxide. The carbon isotope composition of fossil fuels and other environments in nature is significantly different. Extensive use of fossil fuels will significantly change the carbon isotope composition of the atmosphere and water bodies, leaving obvious geological traces in stalagmites, glaciers and other sediments.
A lonely North American spruce on Campbell Island in the southern hemisphere. Its annual ring layer shows that radiocarbon peaked in 1965, and researchers tend to mark this year as the beginning of the Anthropocene.
Scientists believe that the deposition of radioactive materials caused by nuclear tests can serve as the “golden nails” that define the Anthropocene.
The fifth and final feature is that the rate of biological extinction has been greatly accelerated, no less than any major biological extinction in history. Without control, 75% of species will disappear forever in the next few centuries.
Dividing the Anthropocene into a new geological age is not only a need for scientific research, but also a reminder to human beings that as a species on the earth, our influence on the earth’s environment has surpassed that of the earth itself, and our capabilities and responsibilities match. Mankind must shoulder the heavy responsibility of defending the earth and protecting our homeland!