A New Ice Age Was Beginning. Then Humans Started Burning Fossil Fuels
Burning fossil fuels may have prevented Earth from entering another ice age, according to a new study published in Science.
The Barnes Ice Cap, covering parts of Canada's Baffin Island, started growing a few thousand years ago before rapidly reversing course beginning in the 1960s as carbon pollution ramped up. This ice cap is the last remnant of the Laurentide Ice Sheet that once covered most of North America.
The research used samples of ancient vegetation and rock records to analyze the growth and retreat of this ice cap. Unlike glaciers, the Barnes Ice Cap is frozen to bedrock, preserving a vegetal record that allowed scientists to reconstruct its history.
Natural climate cycles
Earth regularly goes through ice ages and interglacial periods due to natural shifts in its rotation and orbit, known as Milankovitch Cycles. The last ice age ended 12,000 years ago, and scientists had evidence suggesting another glaciation period was beginning.
The planet's natural climate cycles would have led to another ice age without human intervention, according to the study. The Barnes Ice Cap had been growing for about 2,000 years before human-caused warming interrupted this natural progression.
Scientific evidence
Scientists used exposure dating techniques to determine when the ice cap first reached its modern size around 3,600 years ago. They then analyzed preserved mosses and lichens to track when the ice expanded again about 2,000 years ago, signaling the potential start of another ice age.
Historical aerial photos showed the ice cap began retreating significantly in the 1960s, reversing 2,000 years of net expansion. The Barnes Ice Cap's edges have retreated an average of 4 meters per year since the 1980s, coinciding with rapidly increasing carbon emissions.
Modern retreat of this glacier has reversed 2,000 years of net expansion—that's a pretty decent chunk of time.
Broader implications
The findings validate a decades-old hypothesis about an impending ice age that climate deniers have misrepresented. In the early 1970s, scientists warned President Richard Nixon about an imminent glaciation period, but this new research shows human-caused warming prevented it.
Media coverage of the 1970s meeting and a colder period at that time have been used by climate deniers as "proof" that global warming isn't happening. The new study adds to evidence that human activity has significantly altered natural climate cycles.
Even as we were just starting to ramp up emissions, we've already done enough damage to cause the major North American ice sheet to already start retreating. That's significant.
The research demonstrates that even as emissions were beginning to increase, humans had already done enough to cause major ice sheets to retreat. This underscores the significant impact human activity has had on Earth's climate system.
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