This graph made with data from the Atmospheric Infrared Sounder on NASA's Aqua satellite shows the concentration of carbon dioxide in Earth's mid-troposphere, located roughly between 3 to 6 miles (5 to 9 kilometers) in altitude.
The sawtooth pattern reflects plants "breathing in" carbon dioxide as they grow, removing this gas from the atmosphere. Soil and plants then release carbon dioxide back into the atmosphere when plants die at the end of the growing season. The upward slope of the graph shows the continuous increase in the concentration of carbon dioxide in Earth's atmosphere.
The concentration of carbon dioxide in the mid-troposphere lags the concentration found at Earth's surface as mixing from the lower to upper altitudes usually takes days to weeks. In addition, changes in concentration of carbon dioxide at Earth's surface are not always carried up to higher altitudes.
While AIRS is able to detect carbon dioxide in Earth's atmosphere to an accuracy of 4 parts per million (ppm), the precision of the measurement clearly corroborates the roughly 2 ppm annual increase in the concentration of this greenhouse gas.