Scott L. Wing is a research scientist and curator at the Smithsonian’s Museum of Natural History.
One of Scott's major research interests is the PETM.
"The Paleocene-Eocene Thermal Maximum (PETM) was an abrupt global warming event.
It occurred at the beginning of the Eocene Epoch, about 55.8 million years ago.
At the start of the event something like 5-10,000 gigatons of carbon were released into the ocean and atmosphere in less than 10,000 years.
As a result of the carbon release, temperatures rose 5-9˚C globally.
The PETM is widely recognized by scientists as the best geologic analogy for the human-induced global warming that is happening now."
However, the current production of greenhouse gases by humans is far faster than the events that caused the PETM.
It took around 150,000 years for ecosystems to recover from this event.