Atmospheric CO₂ Trends

Fossil fuel combustion and other human activities are now increasing the atmospheric carbon dioxide (CO₂) abundance to unprecedented rates. It is estimated that approximately 36 billion tons of CO₂ are added to the atmosphere each year. The large graph shown here is an animated version of the standard Keeling curve from 1980 to September 2014. The red line denotes ground-based measurements from the Mauna Loa Observatory in Hawaii, while yellow denotes observations from the South Pole Observatory. Purple denotes the global trend. The smaller graph in the upper left shows satellite measurements of tropospheric CO₂ concentrations (white dots) at different latitudes from September 2002 to September 2014, obtained by the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instruments. Note how the Northern Hemisphere has greater variably and generally higher levels of CO₂ than the Southern Hemisphere.

In May of 2013, these emissions pushed the monthly average CO₂ concentrations above 400 parts per million (ppm)—a level that has not been reached during the past 800,000 years. These ever-increasing levels are raising concerns about greenhouse-gas-induced climate change.