The last time carbon emissions were this high, dinosaurs roamed the Earth.
And if that isn't daunting enough, the human-driven release today is happening about 10 times faster than any event since that era, a new study has found.
Researchers analyzed the biological signatures of deep-sea sediment samples collected off the coast of New Jersey and found the current release of carbon into the atmosphere is "unprecedented during the past 66 million years."
Candace Major, program director of the National Science Foundation's Division of Ocean Sciences, which funded the research, said in a statement that the study of “one of the most dramatic episodes of global change since the dinosaurs” shows the world has entered “uncharted territory”
The study's research team looked at sediments dating back to a climate event 56 million years ago called the Paleocene-Eocene Thermal Maximum, or PETM. It was believed to be the largest carbon release since the dinosaurs went extinct 66 million years ago.
Over roughly 4,000 years, the PETM caused sea surface and continental air temperatures to rise more than 9 degrees Fahrenheit and brought drought, flooding and insect plagues. Some species became extinct because of it.
But carbon emissions during the PETM were less than 4 billion tons annually, according to the study, published on Saturday in Nature Geoscience. Current carbon emissions from human sources reached a record high of around 37 billion metric tons in 2014.
University of Hawaii professor Richard Zeebe, who led the research, said because today's carbon emission rate is unprecedented over such a long period in the Earth’s history, the world has effectively entered a "no-analogue" state.
"This represents a big challenge for projecting future climate changes because we have no good comparison from the past," he said in a statement.
Zeebe added that the PETM findings suggest that today's massive burning of fossil fuels could have much longer-lasting effects.
"If you kick a system very fast, it usually responds differently than if you nudge it slowly but steadily," he said. "It is likely that future disruptions of ecosystems will exceed the relatively limited extinctions observed at the PETM."
The study comes less than two weeks after the National Oceanic and Atmospheric Administration's Mauna Loa Observatory in Hawaii showed that carbon dioxide levels in the atmosphere climbed more during 2015 than any year in its 56 years of research.
"Carbon dioxide levels are increasing faster than they have in hundreds of thousands of years," said Pieter Tans, lead scientist of NOAA's Global Greenhouse Gas Reference Network, in a statement. "It’s explosive compared to natural processes."