Planet-warming greenhouse gases are "building up, much like trash in a landfill," one researcher said.

One of the major drivers of the exceptional heat building within Earth’s atmosphere has reached levels beyond anything humans have ever experienced, officials announced on Thursday. Carbon dioxide, the gas that accounts for the majority of global warming caused by human activities, is accumulating “faster than ever,” scientists from NOAA, the Scripps Institution of Oceanography and the University of California San Diego found.

“Over the past year, we’ve experienced the hottest year on record, the hottest ocean temperatures on record, and a seemingly endless string of heat waves, droughts, floods, wildfires and storms,” NOAA Administrator Rick Spinrad said in a press release. “Now we are finding that atmospheric CO2 levels are increasing faster than ever.”