Mayank Chhaya-
Has Earth already entered the Anthropocene Age, or the age of humans?
It is more than likely that it has, and it has done so faster than any geological age so far. At the heart of this global transformation is human activity since the mid-20th century.
For geologists to declare a new epoch takes a great deal of time because geological epochs take thousands of years or even millions of years to make in order for them to identifiably alter Earth’s surface.
However, the Anthropocene seems to have unfolded disturbingly fast and propelling its advent goes to the very heart of the raging climate crisis debate. That is because several markers which are considered evidence in the way Earth’s surface has changed since the mid-20th century are direct consequences of human activity.
Professor Jan Zalasiewicz, a geologist at the University of Leicester in the United Kingdom and a former chairman of the Anthropocene Working Group (AWG), tasked with determining the rise of the new age, listed them in a conversation with the online show Mayank Chhaya reports (MCR).
“There is a whole range of what you call stratigraphic proxies, that is markers of some kind of environmental change and which are trapped within sediments. One kind is simply physical (such as) plastic particles, microplastics, fibers which are washed into lakes and seas. They are found worldwide in sedimentary layers, and they begin to appear about the mid-20th century,” he said.
Being a global surface impact is the primary condition for a period to be classified as a distinct geological period.
Other markers that Professor Zalasiewicz listed are different types of new chemicals such as pesticides and DDT in trace amounts found in sediments, chemistry of carbon because of the largescale burning of coal, oil and gas that has changed the isotopic chemistry, proportion of light Carbon12, heavy Carbon13, fly ash as well as radioactive particles unleashed by hydrogen bomb tests in the early 1950s. All of these show upsurge around the mid-20th century, a period which is now beginning to seem most likely when the rise of the Anthropocene may be pegged. As pointed out by Zalasiewicz, all these markers are found globally.
Of course, whether there will be a scientific consensus over the advent of the Anthropocene Age is a subject of voting by the members of the AWG that is currently ongoing. There are expectations that the process will be over by end of this year and new age declared where for the first time in Earth’s 4.54 billion history a single species, namely humans, would have impacted the planet so dramatically.
According to Professor Zalasiewicz, the early 1950s seem to be the “sharpest most applicable time marker to mark the beginning of a unit of time.” That would seem to indicate that the beginning of the new epoch, the age of humans, would be likely fixed in the early 1950s.
There are nine sites worldwide which are being examined to establish changes in sedimentary layers which could be directly attributed to human activity. According to the AWG, the nine sites are in Beppu Bay near Kyushu Island, Japan, Flinders Reef, Coral Sea, Australia, Gotland Basi, Baltic Sea, Palmer ice core, Atlantic Peninsula, Searsville Lake, California, U.S., Sihailongwan Lake, Jilin Province, China, Śnieżka peat bog, Sudetes Mountains, Poland and West Flower Garden Bank, Gulf of Mexic.
If the 1950s-time marker is indeed confirmed, then it would mark the end of the Meghalayan Age, named after the northeastern Indian state of Meghalaya. Geologically, we currently live in what is known as the Meghalayan Age named after the northeastern Indian state. It began some 4200 years ago, and its onset saw widespread droughts across the world that disrupted civilizations in Egypt, Greece, Syria, Palestine, Mesopotamia, the Indus Valley, and the Yangtze River Valley.
For a period to be called an Age on a geologic timescale its climatic impact has to be as global as possible and has to be associated with a rock or sediment type. In the specific case of the Meghlayan Age, it was about a spike as evident in perturbation of oxygen atoms present in the layers of a stalagmite rising from the floor of Mawmluh Cave in Meghalaya.
The Meghalayan Age itself is part of the 12000-year-long Holocene Age.
One of the controversies about the Anthropocene Age is that many geologists do not yet accept it to be an epoch. As Zalasiewicz pointed out, they find it “disturbingly short, lasting a human lifetime” compared to other ages which were thousands of years and even millions in the making. The formalization of the new epoch depends first on the AWG voting followed by several other rounds of back and forth within the scientific community.
Zalasiewicz acknowledged that the Anthropocene condition, the planetary state, will be very long-lived. He said it is hard to see how the climatic consequences “will not last many tens of thousands of years.” He also said it is already the beginning of a “different kind of planet” given that the course of biological evolution is already changing and therefore Earth’s future paleontological evolution will also change.
The rapidity of the likely emergence of the new epoch from the mid-20th century can only be compared, according to Zalasiewicz, to the meteor strike that wiped out dinosaurs and ended the Cretaceous Period some 65 million years ago. He said that is the only boundary on Earth that is sharper than what we are experiencing now in terms of geological transformation. “It is a hammer blow,” he said.
Taken together, the recognition of a new epoch has global political, economic and sociocultural consequences and that may make the debate more difficult.
(Photo of Zalasiewicz is courtesy of the University of Leicester.)
