Human activity has helped cause carbon levels to rise to a rate that hasn't been seen on planet Earth in three million years, researchers have revealed.

A study published Wednesday by the Potsdam Institute for Climate Impact Research in Germany showed that the last time carbon dioxide was detected in the planet's atmosphere at the level it is now was during the Pliocene epoch, which took place 2.6 to 5.3 million years ago.

Authors of the report, which was published in Science Advances, warned that while global temperatures have not yet risen more than 2º Celsius (3.6º Fahrenheit) above industrial levels in the past three million years, they likely will if "climate inaction" on the part of world governments continues.

"It seems we're now pushing our home planet beyond any climatic conditions experienced during the entire current geological period, the Quaternary," said Matteo Willeit, lead author of the study, "a period that started almost three million years ago and saw human civilization beginning only 11,000 years ago. So, the modern climate change we see is big, really big; even by standards of Earth history."

"It seems we're now pushing our home planet beyond any climatic conditions experienced during the entire current geological period." —Matteo Willeit, climate scientist

The report suggested that sea levels could rise as much as 6.5 feet in the next 200 years if humans do not end fossil fuel drilling and carbon emissions. The last time carbon levels were where they are now, sea levels were 65 feet higher, according to the Potsdam Institute.

According to the computer simulation the Institute used in the study, CO2 levels "should not be higher than 280 parts per million without human activity."

Carbon levels are currently at 410 parts per million and rising.

The study was published about three months after youth around the world began holding weekly demonstrations demanding that their elected leaders pass meaningful legislation to end carbon emissions from human activity and shift to a zero-carbon economy.

As students in Ireland, Sweden, Uganda, and other countries gathered for another climate strike, the climate action group Defend Our Future tweeted that the Institute's study shows "there's no time to waste" for global leaders to take meaningful climate action.