Concentrations of carbon dioxide in the atmosphere have risen above 400 parts per million (ppm) in recording stations across the Arctic going as far south as Mongolia, reports the Associated Press. Such levels have not been seen in at least 800,000 years according to researchers. Carbon levels fluctuate depending on the region and the season and scientists say global concentrations will likely remain at around 395 ppm for the time being. Crossing the 400 ppm threshold “[is] a reminder to everybody that we haven’t fixed this and we’re still in trouble,” Jim Butler, global monitoring director with the U.S.’s National Oceanic and Atmospheric Administration’s (NOAA) Earth System Research Lab, told the AP. Prior to the Industrial Revolution, global carbon levels were stabilized at around 275-280 ppm. However, the burning of fossil fuels such as coal and gas, cement production, vast deforestation, industrialized agriculture, and other recent human impacts has resulted in carbon levels skyrocketing.