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

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

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

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

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

The last time humans experienced levels this high was... never, Peter Gleick, a climate scientist and co-founder of the nonprofit Pacific Institute research group, tweeted last month when data showing CO at nearly 415 ppm was released.

Tuesdays announcement comes as climate change grows as an issue on the 2020 presidential campaign trail, with Democratic front-runner Joe Biden coming under fire for earning one of the lowest scores on a rating of climate-conscious candidates by the environmental group Greenpeace last week.

President Donald Trump , meanwhile, is working to crack down on federal climate reports, which have cast an unflattering light on his decision to pull out of the Paris Agreement and retract several U.S. environmental policies. Recently, his administration began pushing for the next federal climate assessment an analysis of peer-reviewed climate science required by Congress at least every four years to use a different methodology and limit climate its projections to just 21 years out.