“The world is changing: I feel it in the water, I feel it on the land and I smell it in the air.” Anyone who has only seen the films in the “Lord of the Rings” series has gotten used to hearing this sentence to hear the sublime voice of Cate Blanchett (the elf Galadriel); In the books, the person who says it is the ent (treelike giant) Treebeard. It is essentially a summary of the conclusion of JRR Tolkien’s fantasy novel: the end of one era and the beginning of a new one, marked by the rule of men. What if it were possible to directly discover something very similar in our 21st century world? Something that proves beyond a doubt that our species irreversibly shaped the Earth?
The answer to this question can be found in many places, but everything points to the fact that the most convincing and consolidated version of it, which will go down in geology and history books, comes from Lake Crawford in Canada. Scientists tasked with formally defining the beginning of the socalled Anthropocene the geological epoch marked by massive human intervention in various aspects of the planet’s functioning use the lake as the epitome of this phenomenon.
Therefore, I invite the reader to take a dip in these alkaline waters. Understanding the details that make the site such a useful example for understanding the Anthropocene is at once a small lesson in the scientific method and a portrait of the often destructive power we have evolved as a species.
One of the most comprehensive analyzes of the Canadian lagoon was published in the journal The Anthropocene Review by a team from Brock University in Canada. The first thing to keep in mind is that Lake Crawford looks like a large funnel: relatively small (2.4 hectares in area) and deep (24 m between surface and bottom). This means that the water layers are well enriched with oxygen, but hardly mix. Due to the high salinity and alkalinity, there is little animal life at the bottom.
And that’s the first big leap: Because of these properties, very stable layers of sediment can be deposited on the bottom of Lake Crawford every year. Every year it’s the same story: in the fall, a darker layer of organic matter sinks to the ground (since we’re in Canada, many trees lose their leaves at this time); In summer, this layer is covered by another, lighter layer of calciumrich minerals. This regularity is never disturbed by socalled bioturbation (e.g. burrowing of aquatic invertebrates into the ground).
In other words: the bottom of the lake is a clock, or rather a calendar. Cylinders of sediment collected from its floor can be dated from year to year with very little uncertainty.
This means that it is possible to accurately determine the appearance of the chemical element plutonium a direct result of the use of nuclear weapons, mainly in military tests from 1948, with a peak in 1967 and a decline in the 1980s Since the elements are radioactive, this signature will strictly be present “forever” (at least from a human perspective).
The same applies to the socalled SCPs (Carbonaceous Spheroidal Particles). They are produced by industrially burning mineral coal and petroleum derivatives at high temperatures. They first appeared in sediments in the second half of the 19th century, but it was not until the early 1950s that their presence increased again. Only human action could cause this phenomenon.
For this reason, scientists propose the year 1950 as the beginning of the Anthropocene. Even if the proposal doesn’t exactly “stick” in this format, it is very difficult to counter the weight of evidence like the layers of Lake Crawford. It is in the water, on land and in the air. And for better or worse, the responsibility lies with us.