Animated model of the concentration of carbon dioxide (CO2) around the Arctic in the mid-troposphere (at 8-12 kilometres up), over the period February 2010 through to February 2011. These data are from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite. The CO2 levels are seen to be highest in the winter, when use of fuel and electricity is much higher. As well as that effect, plant growth in the spring and summer takes up a huge amount of carbon from the atmosphere during photosynthesis. Atmospheric CO2 levels are increasing very quickly, however, which can lead to the atmosphere trapping more heat, as CO2 is a greenhouse gas. The Arctic is expected to be the region most affected by this rise in temperatures.