A team of researchers has found a way to detect trace gases down to concentrations at the parts-per-quadrillion level using a new variation on the photoacoustic effect, a technique that measures ...

And he found that the annual average was 315 parts per million (ppm). He continued his measurements, at Mauna Loa and elsewhere, for almost 50 years. Throughout that time the annually wobbling ...

explains the importance of measuring a CO 2 concentration of 400 parts per million at the observatory that his father, Charles Keeling, set up. Catherine Brahic: The Mauna Loa Observatory in ...

Record global carbon dioxide concentrations surpass 400 parts per million in March 2015. ScienceDaily . Retrieved June 2, 2025 from www.sciencedaily.com / releases / 2015 / 05 / 150507084211.htm ...

For the first time in human history, the concentration of carbon dioxide in the atmosphere has reached 400 parts per million (ppm). The arrival at this threshold represents a powerful symbol of ...