Hawaii’s Mauna Loa Observatory just captured an ominous sign about the pace of global warming. Atmospheric levels of planet-warming carbon dioxide aren’t just on their way to yet another record high this year — they’re rising faster than ever, according to the latest in a 66-year-long series of observations.

Carbon dioxide levels were 4.7 parts per million higher in March than they were a year earlier, the largest annual leap ever measured at the National Oceanic Atmospheric Administration laboratory atop a volcano on Hawaii’s Big Island. And from January through April, CO2 concentrations increased faster than they have in the first four months of any other year.