The National Oceanic and Atmospheric Administrationannounced Tuesday that global carbon dioxide concentrations last month were the highest since it started recording them more than half a century ago.

With CO 2 peaking at 414.7 parts per million in May ― the month when global CO 2 is typically at its highest ― the measurement marks the seventh consecutive year of concentrations steeply rising and the second-highest annual jump in CO 2 since NOAA started recording this data 61 years ago.

“It’s critically important to have these accurate, long-term measurements of CO 2 in order to understand how quickly fossil fuel pollution is changing our climate,” Pieter Tans, a senior scientist in NOAA’s Global Monitoring Division, said in a news release Tuesday.

The current growth rate of CO 2 concentrations is shocking and unprecedented, but if anything, Tans said, the measurements are conservative, and they’ve “underestimated the rapid pace of climate change being observed.”

Though NOAA’s data goes back only to 1958, other research typically done on tiny bubbles of ancient air trapped in ice sheets shows that CO 2 has never been this high in the entirety of human history and possibly millions of years before humans ever walked the Earth.