The concentration of carbon dioxide (CO2), one of the most harmful greenhouse gases on our planet, touched record high last month.

According to the recent set of observations taken at the Mauna Loa Observatory in Hawaii, world’s oldest continuous CO2 monitoring station, the concentration of the gas in our atmosphere went up to a whopping 410.31 parts per million (ppm) in the month of April.

These levels have never been this high in the history of human life. In fact, according to a press release from the Scripps Institution of Oceanography at the University of California, San Diego, it is the highest in the last 800,000 years. Before the beginning of the Industrial Revolution, the levels of CO2 fluctuated but never crossed 300ppm.

However, in the last few centuries, the trend has only been moving upwards. When the observatory started collecting continuous data on CO2 in 1958, popularly known as the Keeling Curve data series, the levels were 315ppm. Since then, there has been nearly a 30 percent increase, with levels cross the 400ppm mark in 2013 and now this.

Carbon dioxide is a major contributor to global warming. The gas traps intense solar heat into the atmosphere of our planet and drives the pressing concern of climate change, something that can have a devastating effect not only on human life but also on flora and fauna on our planet. Among methane, nitrous oxide and others, carbon dioxide is the most prevalent one, thanks to a chunk of human activities such as deforestation and burning of fossil fuels. Natural processes like respiration and volcanic eruptions also contribute to CO2 levels in the atmosphere.

 “We keep burning fossil fuels. Carbon dioxide keeps building up in the air,” geochemist Ralph F. Keeling, who currently directs the Scripps CO2 program, said in a statement. “It’s essentially as simple as that.”

The monitoring project was started by his father Charles David Keeling (thus the name) and operated under his direction until his passing in 2005. Along with CO2 monitoring, Ralph Keeling also has a parallel program at SIO to study and analyze the changes in levels of oxygen from air samples collected at stations around the world. There, the trend has been declining from year to year much to the worry of climate experts around the globe.

Following the update on CO2 levels, Katharine Hayhoe, a climate scientist at Texas Tech University, expressed concerns over global warming in a tweet.

“As a scientist, what concerns me the most is not that we have passed yet another round-number threshold but what this continued rise actually means: that we are continuing full speed ahead with an unprecedented experiment with our planet, the only home we have.”

The report of the latest record came just around the same time when a city in Pakistan witnessed the highest ever temperature recorded on Earth at 50.2 degree Celsius.