Outside In | Long after we are gone, a remote Canadian lake will show how we set about destroying Earth as a habitat

Scientists trying to date the start of the Anthropocene epoch have found in Lake Crawford’s sediment an exquisite record of environmental change over millennia

It’s an important reminder that humans are now a ‘geological superpower’ in the process of changing our planet forever – and not for the better

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Lake Crawford near Milton, Ontario, Canada, on April 12. It could be the geological “golden spike” that marks Earth’s entry into a new Anthropocene era. Photo: AFP

Published: 4:45pm, 14 Jul 2023

Imagine aliens landing on earth 500,000 years from now. By then, humans are likely to be long gone, exterminated by the global warming triggered by our orgy of carbon dioxide generation, environmental destruction and pollution.

This week in Lille in France, the obscure International Commission on Stratigraphy has been holding its fourth congress, focused on work of immense value to visiting aliens: will there be anything in the geological record that shows we were here? If so, what will be the “golden spike” that sets a time and date to when humans set about destroying the balmy equilibrium that, for 11,700 years of the Holocene epoch, enabled Homo sapiens to thrive and distinctively shape the world?

All this revolves around the heated debate among geologists and climatologists about whether humans have had so powerful an impact on Earth that we have tipped us out of the Holocene into the Anthropocene epoch, coined by chemistry Nobel laureate Paul Crutzen two decades ago.

At the heart of the Lille congress, a small but highly influential group called the Anthropocene Working Group reported on these two huge geological questions. Their conclusions? Yes, we have left markers across the globe that are likely to still be clear 500,000 years later; and the date we flipped from Holocene to Anthropocene should be set in the early 1950s.

After examining a shortlist of 12 locations across the world that can provide the clearest markers of this flip, and identify the impact that humans had on Earth, they agreed to focus on Lake Crawford, a tiny, remote lake around 60km west of Toronto in Canada.

Lake Crawford is special because sediments at the bottom of the lake provide an exquisite record of environmental change over millennia, allowing us to see year-by-year changes in Earth’s geological history.

.css-1m2rp1p{color:#34b8b5;}Outside In | Long after we are gone, a remote Canadian lake will show how we set about destroying Earth as a habitat

Outside In | Long after we are gone, a remote Canadian lake will show how we set about destroying Earth as a habitat