56 million years ago, a shocking warm period appeared out of nowhere. In just 500,000 years temperatures throughout the planet shot up by as much at 8 degrees Celsius, triggering regional extinctions and sparking chaos in ecosystems.
Now, a new study from an international team of researchers led by the University of Southampton is attributing the dramatic change to a volcanic supereruption. The team reached their conclusion after taking another look at the Palaeocene-Eocene Thermal Maximum (PETM). The researchers were determined to find the source of the huge release of carbon dioxide that took place at the time.
As we know, carbon sources often leave a signature. Carbon-12, for instance, is the primary variant of the element that is trapped within the fossil fuels that we burn. It is by tracing this fingerprint that we understand our own contribution to the carbon dioxide in the atmosphere.
The team analyzed the geochemistry of the remnants of tiny sea creatures known as foraminifera. Their shells are typically made of calcium carbonate, and the carbon within them can help researchers determine what kind of carbon releases were featured in the sea 56 million years ago. By combining this data with a climate model, the team was able to calculate not only how much carbon was unleashed during the PETM, but also where it came from.
They determined that the final carbon amount in the atmosphere was 30 times the amount humanity has created to date. At the time, the only thing that could have caused such a release was the continental rifting that occurred when Greenland was splitting from Europe, and large upwellings of mantle material were triggering a high degree of melt, generating volcanism.
Essentially, the PETM was caused by a gigantic melting zone that permitted a long-lasting volcanic supereruption to change the world. This is, by far, the most convincing theory that has been introduced to date. And it’s worth noting that the rapidity of the climate change taking place back then is still being overshadowed by the warming caused by humans today.
Source: IFL Science