This graph displays earth's atmospheric oxygen levels from 1991 up to the present. The graph is customizable and can be resized, printed, or pasted into your website. This is a free service, but we do ask for a donation if you find this useful. This is a project of the 2 Degrees Institute, a non-profit organization.
Changes in atmospheric oxygen levels are measured at the Scripps Institution of Oceanography at La Jolla, California under the Scripps O2 Program. Since 1991, air samples have been collected on a consistent basis from stations around the world to provide a global and hemispheric perspective on oxygen variability. The Scripps O2 Program is under the direction of Professor Ralph Keeling.
The Scripps Institute report oxygen measurements as changes in the O2/N2 ratio of air relative to a reference. They compute:
δ = ((O2/N2)sample – (O2/N2)reference)/ (O2/N2)reference)
where (O2/N2)sample is the O2/N2 mole ratio of an air sample and (O2/N2)reference is the O2/N2 mole ratio of their reference. Their reference is based on tanks of air pumped in the mid 1980s which are stored at the Scripps Institute laboratory in La Jolla, California.
Learn more about units and terms here or get answers to frequently asked questions by accessing the graph menu above.
Dr. Pieter Tans
NOAA's Earth System Research Laboratory
Dr. Jeremy Shakun
Boston College
Dr. Geoff Dutton
NOAA's Earth System Research Laboratory
Dr. Ed Dlugokencky
NOAA's Earth System Research Laboratory
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