Scientists in Hawaii have made a shocking discovery. According to a report from the Washington Post, Earth is currently experiencing the highest rates of atmospheric carbon emissions in the past 66 million years.

A recent study from scientists at the University of Hawaii at Manoa reveals that the current rate of carbon emissions has surpassed the last great period of emissions, the Paleocene-Eocene Thermal Maximum, or PETM.

The PETM occurred roughly 56 million years ago, when sudden and massive carbon emissions caused the planet to warm rapidly. The period of rapid heating led to a massive loss of life on Earth, particularly in the oceans where acidification wreaked havoc on the sea creatures of the time.

Scientists aren’t sure exactly what caused the PETM, but the sudden jump in atmospheric CO2 was well documented in the fossil record. Theories as to the cause of the PETM include thawing Arctic permafrost, the release of methane trapped below the sea floor, or massive volcanic eruptions that quickly increased the amount of carbon in the atmosphere.

Scientists believe that the PETM resulted in a 5-degree C increase in average global temperature, which spelled disaster for life on Earth at the time. This makes the current readings from the University of Hawaii team’s study even more alarming – they say we’re putting carbon into the atmosphere at a higher rate than the event millions of years ago.

The study was published in the journal Nature Geoscience, and warns that the carbon being pumped into the atmosphere in the present could lead to another period of mass extinctions on Earth.

According to professor Richard Zeebe, “If you look over the entire Cenozoic, the last 66 million years, the only event that we know of at the moment, that has a massive carbon release, and happens over a relatively short period of time, is the PETM. We actually have to go back to relatively old periods, because in the more recent past, we don’t see anything comparable with what humans are currently doing.”

A news release from the University of Hawaii describing the details of the study can be found here.