A new study led by a University of Hawaii scientist has found that humans are releasing carbon into the atmosphere about 10 times faster than during any time in the past 66 million years.

The research paper — published in Nature Geoscience by Richard Zeebe, a professor in UH Manoa’s School of Ocean and Earth Science and Technology, and colleagues — examined changes to Earth’s temperature and atmospheric carbon dioxide since the end of the age of the dinosaurs.

The study adds to the growing body of evidence showing how humans are helping to modify Earth’s climate.

Zeebe and co-authors Andy Ridgwell of the University of Bristol and University of California, Riverside, and James Zachos of UC Santa Cruz developed a new scientific method to help them take a closer look at the onset of a time long ago when Earth endured another period of accelerated carbon release and global warming.

The Paleocene-Eocene Thermal Maximum, or PETM, occurred some 56 million years ago, resulting in atmospheric warming of 9 degrees or more, ocean acidification, the extinction of some deep-ocean species and the forced migration of animals.

The new method combines analyses of the chemical properties of PETM sediment cores taken from formerly submerged New Jersey, along with numerical simulations of Earth’s climate and carbon cycle.

This breakthrough allowed the researchers to calculate how fast the carbon was released during the PETM, how fast Earth’s surface warmed and the duration of the event’s onset — at least 4,000 years.

It turns out that the carbon release by natural forces within the earth 56 million years ago — among them the melting of methane hydrates in the ocean seabed — was much more gradual than today’s human-generated carbon release into the atmosphere.

Carbon-emission rates from humans reached a record high in 2014 of about 37 billion metric tons of carbon dioxide, while the maximum sustained carbon release rate during the PETM was less than one-tenth that rate, or less than 4 billion metric tons of carbon dioxide per year, Zeebe and his colleagues estimated.

“We conclude that, given currently available records, the present anthropogenic (human-generated) carbon release rate is unprecedented during the past 66 million years,” the scientists said in their paper.

Even if large climate transitions in the past were relatively seamless, today’s extreme rates of carbon release make it hard to say what kind of climate changes we face in the future, Zeebe said.

“Because the rate of our carbon release is so fast, the chance of future extinctions and disruptions of ecosystems is higher than during the PETM,” Zeebe said.

But the oceanography professor said he doesn’t believe our world is doomed.

“The issue is urgent,” he said. “The viable solution is to reduce emissions. But it has to be done quickly. It has to be done now. If we can reduce emissions rapidly, the prognosis for the future looks much better.”

Funding for the research was provided by the National Science Foundation and the European Union.

“In studying one of the most dramatic episodes of global change since the end of the age of the dinosaurs, these scientists show that we are currently in uncharted territory in the rate carbon is being released into the atmosphere and oceans,” Candace Major, program director in the National Science Foundation’s Division of Ocean Sciences, said in a news release.

The researchers say they plan to continue examining the PETM to study other aspects of the event, including how severe ocean acidification was then and what impact it had on calcifying organisms in the ocean. This could offer insight about what to expect as our climate continues to warm and acidification accelerates.