The Last Time CO2 Emissions Were This High the Arctic Had Palm Trees: It's Terrifying

greenhouse gas emissions
Carbon emissions reached an all-time high in 2018. iStock

The rate at which carbon dioxide is being pumped into the atmosphere is now about 10 times higher than what was produced during the last major period of global warming. Indeed, the last time CO2 emissions were this high, the Arctic was home to palm trees and crocodiles.

In a study published in the American Geophysical Union journal Paleoceanography and Paleoclimatology, researchers have looked at the current rate of CO2 production and compared it with what was happening during the Paleocene-Eocene Thermal Maximum (PETM)—a period of global warming that took place about 56 million years ago.

During the PETM, huge amounts of CO2 were expelled into the atmosphere, causing global temperatures to rocket from between 5 to 8 degrees Celsius (41 to 46 degrees Fahrenheit). At its peak, global temperatures reached about 23 degrees Celsius (73 degrees Fahrenheit)—which is about 7 degrees higher than today. Current climate change models indicate global temperatures will increase by around 4 degrees Celsius (39 degrees Fahrenheit) unless we drastically reduce the amount of greenhouse gases being pumped into the atmosphere.

What was behind the PETM is unknown. However, scientists have been able to estimate that between 3,000 and 7,000 gigatons of carbon accumulated over 3,000 to 20,000 years.

During the PETM, the poles were largely free of ice The influx of CO2 and soaring global temperatures probably caused widespread extinctions in marine environments. It also caused terrestrial animals to get smaller and migrate north toward cooler climates.

Scientists often use the PETM as a model for what might happen to Earth's climate in the future.

In their latest study, researchers developed a way to compare current CO2 emissions to those seen during the PETM on the same time scale. Findings showed current emissions are up to 10 times higher than what was seen during the PETM. Researchers estimate that if CO2 emissions continue on their current trajectory we could be just 140 years from reaching CO2 levels not seen since the PETM, with 3,000 gigatons released by the year 2159. It would reach more than 7,000 gigatons by 2278.

"To me, it really brought home how rapidly and how great the consequences are of the carbon we're producing as a people," lead author Philip Gingerich from the University of Michigan said in a statement. "You and I won't be here in 2159, but that's only about four generations away. When you start to think about your children and your grandchildren, and your great-grandchildren,

"The fact that we could reach warming equivalent to the PETM very quickly, within the next few hundred years, is terrifying," Larisa DeSantis, a paleontologist at Vanderbilt University, who was not involved in the study, said in a statement. "It's not just about 100 years from now; it's going to take significant periods of time for that carbon dioxide to make its way back into Earth's crust. It's not a short-term event. We're really committing ourselves to many thousands of years of a warmer world if we don't take action quickly."

As part of the Paris Agreement, drafted in France in 2015, nations across the world agreed to limit greenhouse gas emissions in a bid to try to keep warming to just 1.5 Celsius (34.7 Fahrenheit) by the end of the century. However, a report by the Intergovernmental Panel on Climate Change released in October last year suggested that countries are unlikely to meet these targets.

A report from December last year also found that global carbon emissions reached an all-time high in 2018, with an estimated 2.7 percent rise over 2018.