Located on Campbell, New Zealand, a remote island in the middle of the Pacific Ocean, this rare 100-year-old Sitka spruce is known as the loneliest tree in the world. There is no other around this. The closest is more than 200 km away in the Auckland Islands. In this state of isolation, you might think that nothing affects you, that the vicissitudes of the rest of the planet are alien to you in your natural paradise, but nothing is further from the truth. As suggested by an international team of researchers, this fir tree is the signal of the arrival of a new geological era, the Anthropocene, marked by human action.
Loneliest tree in the world
The Sahara desert is the largest of its kind and the trees are not exactly the beings that inhabit it the most. However, from time to time it is possible to admire the occasional acacia emerging from the desert terrain. The most isolated tree in the world was an acacia with a crooked, spindly trunk, the only tree to stand for at least 250 miles around, and for 300 years it was the only testament that the desert was once a greener place and more fertile.
This new era began between October and December 1965, as published by the team in the journal “Scientific Reports”. The researchers were able to identify this profound change so precisely because of what is known in geology as a “golden nail” found in the heartwood, the central part of the trunk, of the solitary Campbell fir. It is a radioactive carbon spike created by the culmination of testing of most of the Northern Hemisphere’s atmospheric thermonuclear bombs in the 1950s and 1960s. The signal was fixed in spruce wood by photosynthesis.
‘A worrying change’
“The impact that nuclear weapons tests have had on the Earth’s atmosphere provides a global signal that demonstrates unequivocally that humans have become the primary agent of change on the planet. This is an important but worrying finding.” says Christopher Fogwill, director of the School. Geography, Geology and Environment at Keele University and lead author of the study. The global atomic bomb signal, captured in the annual rings of this invasive tree species, represents a line “after which our collective actions have left an indelible mark, which will define this new geological epoch for generations to come,” he says. the investigator
Scientists have been debating for years about the existence of a new geological epoch called the Anthropocene, which indicates the point at which human influence on the planet significantly changed the natural world. However, for a new epoch to be officially declared, there must be a clear and precise “global” signal that can be detected in the geological formation materials of the future. For the authors of the new study, this radiocarbon peak is that signal.
“We are incredibly excited to have found this signal in the southern hemisphere on a remote island because for the first time we have a well-defined global signature for a new epoch that could be preserved in the geological record. Thousands of years from now, this ‘golden nail’ should still be a detectable marker of humanity’s transformation of the Earth,” said Chris Turney of the University of New South Wales, also the lead author of the report.
A world brand
In the northern hemisphere, the atmospheric radiocarbon peak occurred in 1964, a signal that is preserved in European trees. It wasn’t until late 1965 that that same peak reached the atmosphere of the southern hemisphere. With that, the signal became global, precise, and detectable in the geological record, meaning it was a perfect fit as a marker of a new epoch.
The tree, from the fir family, is itself an anomaly in the Southern Ocean. It occurs naturally along the Pacific coast of North America but is credited with being planted on Campbell Island by the Governor of New Zealand in 1901. Oceanic weather has had an unusual effect on the spruce. Although it has grown to 10 m tall, it has never produced cones, suggesting that it has remained in a permanently juvenile state.
For Mark Maslin, from University College London, co-author of the study, this extraordinary tree, planted far from its normal habitat by humans, has become a marker of the changes we have made to the planet. In his opinion, he clearly shows that “in this new era no part of our planet is spared from human action.”
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