At several points in the history of our planet, increasing amounts of carbon dioxide in the atmosphere have caused extreme global warming, prompting the majority of species on Earth to die out.
In the past, these events were triggered by a huge volcanic eruption or asteroid impact. Now, Earth is heading for another mass extinction – and human activity is to blame.
I am an Earth and Paleo-climate scientist and have researched the relationships between asteroid impacts, volcanism, climate changes and mass extinctions of species.
My research suggests the current growth rate of carbon dioxide emissions is faster than those which triggered two previous mass extinctions, including the event that wiped out the dinosaurs.
The world’s gaze may be focused on COVID-19 right now. But the risks to nature from human-made global warming – and the imperative to act – remain clear.
Past mass extinctions
Many species can adapt to slow, or even moderate, environmental changes. But Earth’s history shows that extreme shifts in the climate can cause many species to become extinct.
For example, about 66 million years ago an asteroid hit Earth. The subsequent smashed rocks and widespread fires released massive amounts of carbon dioxide over about 10,000 years. Global temperatures soared, sea levels rose and oceans became acidic. About 80% of species, including the dinosaurs, were wiped out.
And about 55 million years ago, global temperatures spiked again, over 100,000 years or so. The cause of this event, known as the Paleocene-Eocene Thermal Maximum, is not entirely clear. One theory, known as the “methane burp” hypothesis, posits that a massive volcanic eruption triggered the sudden release of methane from ocean sediments, making oceans more acidic and killing off many species.
So is life on Earth now headed for the same fate?