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About 55 million years ago global temperatures spiked. Then, as now, sea levels rose, the oceans became more acidic, and species disappeared forever.
Little wonder, then, that researchers view this ancient event – known as the "Palaeocene-Eocene Thermal Maximum" or PETM – as a potential goldmine of useful information for understanding modern climate change.
We now know that the PETM was one of the most rapid and dramatic instances of climate change in Earth's history. Its causes are still up for debate, but there seem to be eerie parallels with the causes of modern climate change. What is absolutely clear is that the PETM's effects were far-reaching. It may have altered the course of life on Earth.
(...) the PETM seems to have been caused by greenhouse gases just like modern-day climate change.
(...) Researchers examined another set of muds that formed at the bottom of the ocean 55 million years ago, this time in the north-west Atlantic. They found banding in the muds that they argued was formed by annual cycles.
When they traced the oxygen and carbon isotope blips associated with the PETM, they found that they were contained in just 13 bands. This means, they said, that the PETM temperature surge came in just 13 years.
This does not imply that the PETM came and went in little more than a decade. All researchers agree that the unusually warm conditions, with global temperatures at least 5 °C above average, lasted about 170,000 years.
What it would imply is that global temperatures ramped up to that 5 °C figure in just 13 years. Today, in contrast, global temperatures have risen about 1 °C since the late 19th century.
If PETM climate change really were so rapid, there would be implications for the event that triggered the warming. To create such a rapid rise in global temperature, the atmosphere would have had to be flooded with greenhouse gases almost literally overnight.
Perhaps the release of gases from the melting of a huge carbon-rich comet that flew too close to the Earth would do the trick.
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