Scientists argue that human influence on the planet pushed it into a new geological epoch, which they’ve called the “Anthropocene”.
Despite our early existence compared to Earth’s age (humans have only been around for 200.000 years, whereas the planet emerged 4.6 billion years ago), the mark we are leaving on our world is already pretty obvious.
We’ve started by chopping down trees in order to clear the land for agriculture. Then we’ve settled permanently and created the first civilisations, that is to say, the first cities. We have also managed to develop complex technologies and learned how to use external sources of energy, including fossil fuels, with consequences we would soon find out.
And it was over the last two centuries – which cover the Industrial Revolution (18th century) and “The Great Acceleration” onset around the 1950’s – that the global effects of human activities have become clearly noticeable.
Humanity has brought about such a planetary change that Paul Crutzen, a Dutch Nobel laureate chemist, could no longer agree that he was living in the Holocene – the current geological epoch which began around 10.000 years ago. So back in 2000, he and a colleague, Eugene Stoermer, decided to coin what they considered to be the new geological epoch we were entering as the Anthropocene – the age of man.
Since then, a fierce debate has been going on among scientists on whether the Anthropocene should be formally recognised as a geological time unit by the International Commission on Stratigraphy (ICS), the organisation that defines such geological time divisions.
Anthropocene proponents argue that humans have become a major geological force shaping our planet. In a short period of time, we have managed to change the composition of the atmosphere (with the release of carbon dioxide) and the chemistry of the oceans (which are now more acid for the same reason). As a result, our climate is changing, glaciers are melting and sea levels are rising, all at rates that exceed the variations occurred in the Holocene.
We have also changed ecology and biology by domesticating other living species (plants and animals), and by interfering in the way they are distributed in the world in number and abundance. For example, there are now more trees on farms than in wild forests, and cattle population has increased to 1.4 billion, about one cow per family. The way we are altering wildlife is not only leading to accelerating rates of extinction, but it is also turning the planet into a homogenised ecosystem.
And we have changed the Earth’s surface by retouring rivers, eliminating forests, building highways and cities, where more than half of us live. On top of that, we (humans) have exponentially grown in number – 7.4 billion today and an expected 9.7 billion by 2050 – consuming more resources than ever before.
Early this year, a new study by the Anthropocene Working Group, published in Science magazine, provided strong evidence that humanity’s influence on Earth will be imprinted in sediments and rocks for millions of years. The appearance of man-made materials in sediments, including aluminium, plastics, and concrete, are an example of that, forming very characteristic and abundant “technofossils”.
But perhaps the most distinctive mark we have left, according to the study, is the radioactive elements (radionuclides) dispersed around the world from the thermonuclear weapons tests conducted in the 1950s.
The original proposal to when the Anthropocene began (made by Crutzen himself) points to the Industrial Revolution on the 18th century. The working group, however, is leaning more to the mid-20th century, right at the beginning of the nuclear age. This time period also coincides with the “Great Acceleration”, when a huge growth in population and consumption patterns occurred as well as significant changes driven by technological advance.
If we can change the planet, let’s do it for the better
But human capacity for intervening on the planet’s systems may not be entirely bad after all. For many Anthropocene advocates, our “geoengineering” skills should now be put to work for the benefit of the planet. High-tech interventions such as newly designed plants that clean the air, or changing ocean chemistry to increase the amount of carbon it absorbs – actively decreasing its levels in the atmosphere – are among the potential solutions.
This doesn’t mean, however, that efforts to significantly decrease the emission of carbon from fossil fuel combustion should cease. On the contrary, making renewable energies increasingly available and cost-effective is another part of the answer.
In fact, creating a collective conscience that humanity is a major force driving changes on our planet as a whole (not just the atmosphere, but the oceans, the ice, and biodiversity) is ultimately what the Anthropocene Working Group wants to stress with the aforementioned study.
The debate on whether the Anthropocene should be officially declared as a new epoch will most certainly continue, at least until the International Commission on Stratigraphy decides on the matter. On one side, enthusiasts of the concept point out its significance in conveying the magnitude of the changes that mankind has made to Earth. On the other, sceptics question the usefulness of a formal recognition of the term for the scientific community.
There’s one thing, though, which both parts seem to agree on: if humans have a decisive influence on the planet, so can they help to build a more sustainable future.