Here's what fossils can tell us about ancient periods of climate change

A study reveals that two dramatic episodes of global warming occurred over 50 million years ago. Image: Shutterstock

While the scale of human-induced global warming is unprecedented, this is not the first time the planet has experienced periods of significant temperature rise. A new study reveals that two significant episodes of global warming occurred over 50 million years ago.

The current climate crisis caused by human activity dates back to the beginning of the last century, and perhaps as far back as 1860. But this is not the first time the planet has been confronted with a significant rise in temperatures. Research by geologists at the University of Utah (USA) suggests that “dramatic” periods of warming occurred around 60 million years ago. "Driving this planetary heat-up were massive emissions of carbon dioxide (CO2) and other greenhouse gases, but other factors like tectonic activity may have also been at play," the researchers note in a news release.

To make these discoveries, the scientists studied microscopic fossil samples taken from drilling cores from an undersea plateau in the Pacific. Specifically, the fossils in question were carbonate shells from creatures similar to plankton. Using a sophisticated statistical model, the researchers were able to reconstruct ocean surface temperatures and atmospheric CO2 levels over two distinct sudden warming events, known as hyperthermals, occurring 54 and 56 million years ago respectively. "The findings indicate that as atmospheric levels of CO2 rose, so too did global temperatures," the news release explains.

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Anticipating future carbon emissions 

Published in the journal Proceedings of the National Academy of Sciences (PNAS), the study suggests that the CO2 emissions released into the air during these two periods are "similar enough to today’s anthropogenic climate change to help scientists forecast its consequences." "Today, human activities associated with fossil fuels are releasing carbon 4 to 10 times more rapidly than occurred during these ancient hyperthermal events. However, the total amount of carbon released during the ancient events is similar to the range projected for human emissions, potentially giving researchers a glimpse of what could be in store for us and future generations," reads the study news release.

Surprising as these results may seem, this is not the first time that studying fossils has revealed the occurrence of global warming. Research, published at the beginning of August, revealed that Greenland was largely ice-free at some point within the last million or so years, when atmospheric CO2 levels were much lower than today. This finding, discovered thanks to the analysis of fossils, is not good news. On the contrary, it could herald a greater risk of sea-level rise than previously predicted.