The humans have done it again: the Anthropocene, another shameful achievement for mankind

Science books have to be modified again. Joining other famous geological epochs of the Cambrian, Jurassic or Pleistocene another one must be added from now: the Anthropocene. On August 2016 a group of experts confirmed what everyone suspected: mankind have been so interventionist in terrestrial processes that the natural cycle have changed irretrievably. We have already suffering the consequences, and the human footprint on our planet will be present until after our demise. 

INTRODUCTION

The history of the modern man, Homo sapiens sapiens, was not easy in the beginning. It is believed that we appeared on the Middle Paleolithic, about 200,000 years ago in Africa. In those days humans were already good hunters, but also good preys, and although the species was thriving and spreading across the planet, this was done slowly and always influenced by severe climate changes. It took 100,000 years to leave Africa and anothers 80,000 to reach America. During all that time and until almost the present day, humans being was at the mercy of the Earth and its whims, which decided at will the fate of our ancestors. However, the Ice Age ended, the Holocene began and thereby unprecedented technological advancement. The industrial revolution definitely transformed humans and the way they interact with the world, which suffered the devastating consequences of an ambitious and unaware species about their enormous global influence.

Humans have been nomadic most of their existence, with a strong dependence on environmental conditions that conditioned their prey. With the agriculture and lifestock the first villages were created, leading to the modern style. Source: Return of Kings.

WHAT IS A GEOLOGICAL TIME AND HOW IT IS POSSIBLE TO ENTER AND LEAVE IT?

At first glance, it may seem a mere syntactical question or a whim of geologists. However, designate a geological time is important when defining long periods of time sharing similar environmental conditions. Normally, a geological period usually lasts no less than 2 million years, and the fossil record is used to find out a major discontinuity in the typical pattern of the biota of that actual period. Therefore, an epoch tend to finish when an abrupt climate change occur (the Pleistocene ends with the last of the great glaciations), leading to changes in the biota (the meteorite that wiped out the non-avian dinosaurs caused the end of the Cretaceous period). However, these abrupt changes must be occur globally and in a short space of time to really be considered as a different geological epoch.

Earth is divided into periods whichare divided into geological epochs. These periods are marked by relatively stable and / or with a characteristic biota. These epochs are usually finished by events that involve drastic changes for living organisms on a global scale. Source: philipmarshall.net.

THE ANTHROPOCENE

The term is not new (it was used for the first time in the mid XIX century during the industrial revolution) but regained importance in early 2000, thanks to Paul Crutzen. This chemist, together with other colleagues, discovered the compounds that were destroying the ozone layer, which makes him to win the Nobel Prize in Chemistry. In his speech, he had special interest in stressing that the Holocene “was over forever” to make way for the Anthropocene, the age of humans. His article in Nature about the Anthropocene was a reference for many scientists working on projects about environmental problems in the Anthropocene epoche. On August 29, 2016, the expert group of the Anthropocene voted at the International Geological Congress (IGC) to formally establish the Anthropocene as a new geological epoch.

The industrial revolution changed the course of Earth forever. Vast amounts of fossil fuels were burned and their products emitted into the atmosphere. The production system took a turn, giving priority to production and thereby to make unprecedented use of the planet’s resources. In the photo, British workers in a factory of agricultural products in 1928. Source: Daily mail.

BUT, WHY ARE WE IN THE ANTHROPOCENE?

As we mentioned before, to change the geological epoch it has to be evident that environmental conditions are changing on a global scale. And that is what is happening since the early 50s of the last century, date in which researchers have officially marked the beginning of the Anthropocene. In this Science article, researchers from around the world gathered geological evidence showing with certainty that mankind has changed the planet severely and it should already talk about another geological era. The researchers also pointed to the products of the many atomic tests of the 50s as the starting point of the Anthropocene.

The nuclear tests of the 50s, like this one in which the first hydrogen bomb (Ivy Mike) was tested, caused the release of large amounts of radioactive materials into the atmosphere. These particles were settled and that has allowed researchers to have evidence in order to demonstrate the impact of human actions on a global scale. Source: CBC.

EVIDENCE OF THE ANTHROPOCENE

Since the beginning of the industrial revolution, more than two centuries ago, numerous anthropogenic deposits have been accumulated in the earth’s crust, from new minerals and rocks to aluminum, cement and petroleum products such as plastics. Just after these lines, we show the main evidence put forward by researchers to justify the change of epoch:

High levels of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), plastics, fertilizers and pesticides in sediments. The burning of oil, coal and other wood products are the source of large amounts of PAHs in the atmosphere, that they just finally end settling in the earth’s crust and living things.Referring to fertilizers, little abundant nutrients in the soil such as nitrogen and phosphorous have doubled in the last century due to the increasing number of crops, many of which following the intensive model to maximize production. Moreover, plastics are already present worldwide. Its high resistance to degradation prevents natural recycling, which causes large quantities to deposit and, especially, to end in the sea, where there are authentic plastic islands, as the Great Pacific garbage patch .

Plastic is the most widely-product made from oil on Earth. Its impact on the environment is one of the most serious at present, and  global sedimentation leaves traces of our presence until thousands of years after our disappearance. Source: The Guardian.

Radioactive elements of nuclear tests. The detonation of the atomic bomb called Trinity in 1945 in New Mexico (USA), was followed by a long list of other nuclear tests during the Cold War. As a result, large amounts of carbon-14 and plutonium-239, among other molecules, were released into the atmosphere and sedimented years later in many parts of the globe, constituting a proof of the great human impact on Earth.

This core, extracted by the geologists that have determined that we are in a new era, shows the accumulation of human origin material in the sediments of a lake in Greenland. In it was found pesticides, radioactive nitrogen, heavy metals, increases in the concentration of greenhouse gases and plastics. Source: Science.

High concentrations of CO2 and CH4 in the atmosphere. From 1850 and especially in the following decades, the levels of these gases in the atmosphere broke with the typical pattern of the Holocene, getting itself to achieve, in our century, 400 ppm (parts per million) of CO2, an increase of more of 150 points from the pre-industrial situation. This increase in atmospheric CO2 has a direct impact on the temperature of the Earth. It is believed that the global temperature has increased by around 1 ° C since 1900, and will increase between 1.5 and 3.5 ° C by the year 2100.

This chart shows the unprecedented increase in CO2, methane and nitrous oxide in the atmosphere. Although CO2 is the best known gas and which has the greatest impact on a large scale, the other two gases have greater power to limit heat dissipation into space. The increase of these gases is closely related to the increase of global temperature. Source: CSIRO.

The increase of the ratio of extinction of living organisms in all parts of the world as a result of human activities. Since 1500 the extinction of species by humans has increased, but is from the XIX century onwards when the extinctions are present in the entire planet. The distribution of species has been disrupted due to human activities such as agriculture and deforestation and the introduction of invasive species, causing changes in the habits of native species and often come to displace and even to extinguish. This unprecedented high extinction ratio is considered by many people as an unmistakable symbol that we are in front of the sixth mass extinction on Earth.

Since the beginning of the industrial revolution, the rate of extinction of vertebrates is 100 times greater than in the past. At this rate, it is estimated that in the following centuries the number of extinct species will reach 75% of the existing ones. The dotted black line in this graph shows the rate of pre-industrialization extinction, while others refer to the cumulative percentage of extinct species since 1500. Source: Science.

FUTURE

Whatever the fate of humanity and future actions undertaken to mitigate climate change, what is clear is that the human footprint will remain indelible in the earth’s surface for millions of years, similar to what occurred after the Permian or Cretaceous mass extincion. The strata will show the follies and excesses carried out by us, perhaps as a warning for the following species that dares to relieve humanity of its status as the dominant species.

REFERENCES

• National Geographic
  
• Science
• El País: Bienvenidos al Antropoceno
• CBC
• Smithsonian
• La Vanguardia
• Anthropocene info
• The Guardian
• El País: La sexta gran extinción está en marcha
• Imagen de portada: CBC