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Among all scientists, geologists are the guardians of time. They do it through a branch called statigraphy that studies the layers of rock - or strata - of the earth's crust. This fossil record allows them to divide the 4.6 billion years of Earth's history into an International Chronostratigraphic Table, classified based on the great changes that have occurred on the planet. 12,000 years ago - at the end of the last ice age - the current era, the Holocene, began . However, since the Nobel Prize winner in chemistry Paul Crutzen proposed the term anthropocene, more and more scientists from different disciplines are using it to describe a new era defined by the changes caused by human beings .
Initially the concept of anthropocene was welcomed with skepticism by geologists, for whom 50, 500 or 5,000 years are only a sigh. But a group of dissidents, headed by stratígrafo Jan Zalasiewicz, accepted that it was an idea worth exploring, both for its scientific base and for its political connotations. Zalasiewicz formed a group to assess whether it was feasible for anthropocene to become part of the Chronostratigraphic Table. In addition to geologists, he invited astrophysicists, environmental science experts, chemists, paleoecologists and archaeologists. In 2016 they stated in an article in the journal Science that the anthropocene is "functionally and stratigraphically distinct" from the Holocene and that, in his opinion, it is a new era. Before being approved, your proposal must be put to the vote in the International Stratigraphy Commission (ICS).
Meanwhile the great debate on the anthropocene keeps other smaller ones inside. It remains to define its starting point . In this aspect, scientists disagree according to the different disciplines.
Geologists believe that the end of World War II is the most coherent date; Industrial activity and nuclear tests of the 1950s will leave an indelible mark on the fossil record. From the environmental sciences the industrial revolution is committed to the beginning, because that was when the concentrations of CO2 and methane began to accumulate significantly in the atmosphere. Archaeologists, on the other hand, oppose both and remember that the ecological footprint accompanies man from the beginning of civilization.
Footprint on the planet
To support this thesis they publish a study in the latest issue of the journal Science - in which 250 scientists have collaborated - and which shows how the first sapiens already had an impact on their environment more than 10,000 years ago. "Even before the first great societies appeared, humans have transformed the landscapes using fire, propagating the species that interested us or clearing and tilling land," explains Erle Ellis, a researcher at the University of Maryland and one of the drivers of the study. . " We have remodeled biodiversity through extinctions and other changes in plant and animal populations and altered greenhouse gas emissions in the atmosphere, which has affected the global climate."
The authors point out that hunting, gathering and fishing were common in most parts of the world 10,000 years ago, but that by the year 1,000 BC they had already been replaced by agriculture and grazing in more than half of the planet. "All these cumulative anthropogenic changes have created the world we live in today," says Lucas Stephens, a researcher at the University of Pennsylvania and first author of the work. "Of course, the scale and pace of these changes have increased dramatically since the beginning of the industrial era."
Learn from the past
Although the authors point out that the current destruction of the environment is happening at an unprecedented rate, they hope this study will help provide a historical context to the problems of the 21st century. "There is a long history of societies that have failed to respond to the environmental challenges of sustainability, especially for social reasons, such as political elites insensitive to the needs of society as a whole," warns Ellis. "Others managed to develop more intensive agricultural techniques that allowed them to increase productivity without extending arable land, through the use of fertilizers, irrigation, the selection of more efficient animals and vegetables. Those societies also distributed food more equitably and others. resources through the use of public barns. "
The study is part of a large project called ArchaeoGLOBE, which uses a system of joint surveys put in common by researchers from around the world to gather a large database that allows analyzing how the relationship with the land has changed throughout the History in 145 different regions. "Our project helps to relate environmental sciences to archeology worldwide," explains Stephens. "Many people have realized that the study of interactions between man and the environment must include archaeological knowledge."
The author cites the publication in early August of a report on land use by the United Nations Intergovernmental Panel on Climate Change. " There is a long history of man-made changes on the planet that has not yet been significantly incorporated into these discussions. That has to change," he adds.
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