Remember when carbon dioxide (CO2) levels in the atmosphere hit a terrifying 400 parts per million (ppm)? That’s number’s old news now – concentrations just reached 410 ppm for the first time in millions of years. Last week, researchers at Mauna Loa Observatory in Hawaii recorded the record-breaking level, and scientists warn the rate of increase will only slow when we reduce our carbon emissions. Mauna Loa Observatory scientists just recorded the first CO2 level above 410 ppm since they began recording in 1958.