Predicting climate change, and the effects thereof, has never been easy. Generally, when scientists need to figure out how something like that will play out, they look to the past to see how things have gone before. That’s precisely what a team from the University of Hawai’i – Manoa School of Ocean and Earth Science Technology was trying to do by looking at the Paleocene-Eocene Thermal Maximum (PETM), an event that happened about 56 millions years ago.


PETM was a pretty dramatic, albeit long-term change in the Earth’s climate. During that time, over a period of about 4,000 years, carbon output increased to about 4 billion metric tons per yea, which is quite a lot. Overall, it’s the largest carbon release in the past 66 million years, pretty much since the dinosaurs died out. So the team has been investigating that period to try and see what might happen to the Earth in the future as a product of human activity over the last century or so.

Here’s the problem though: we’re outputting carbon at almost ten times the rate of PETM. 2014 saw a record high of 37 billion metric tons of carbon introduced into the atmosphere. That is a far higher, and more sudden, impact than was seen during PETM. And that means that we can’t really predict what’s going to happen based on the past. We know that there were a number of extinctions and ecosystem disruptions during PETM, and that we can expect much the same, but at a significantly higher rate, and much faster. Most people are only concerned with the rest of this century, but our actions will have an impact on the Earth for much, much longer. PETM lasted 4,000 years, but at the rate we’re going, we’re going to produce the same amount of carbon in something like 400 years. Kicking a system like the global climate, instead of just nudging it, is going to work out very differently.