Record high carbon dioxide The concentration of carbon dioxide (CO₂) in the atmosphere recently broke two records at Mauna Loa, Hawaii, CO₂ was 421.63 in the week starting May 29, 2022, while CO₂ was 420.99 ppm in May 2022. Earlier, very high daily and hourly measurements were recorded at Mauna Loa, as illustrated by the image below, showing one hourly measurement of 424 ppm (on May 28, 2022), as well as sequences of daily measurements in the green insets. The image below shows carbon dioxide concentration rising over the past few years, with surface flask measurements well above 422 ppm at Mauna Loa recently. Carbon dioxide concentration is even higher over the Arctic. The image below shows carbon dioxide approaching 430 ppm at Barrow, Alaska. To get an idea how much greenhouse gases have risen, a 2021 study points at concentrations of 190 ppm for CO₂, 370-375 ppb for CH₄ and 200-245 ppb for N₂O some 18 ka to 21 ka. By comparison, the MetOp image below shows a...