The Keeling Curve Hits 420 PPM

Rob MonroeMost Popular, Videos

Levels of the greenhouse gas carbon dioxide eclipsed 420 parts per million for the first time in human history in 2021. Scripps Institution of Oceanography updated this animation, which explains the rise of carbon dioxide concentration in the atmosphere over the past 300 years and the measurement our researchers collect at Hawaii’s Mauna Loa, known as the Keeling Curve. When … Read More

What Does This Number Mean?

Rob MonroeMeasurement Notes

Repost of April 2013 entry The Mauna Loa carbon dioxide (CO2) record, also known as the “Keeling Curve,” is the world’s longest unbroken record of atmospheric carbon dioxide concentrations.  

A note on recent readings

Rob MonroeMeasurement Notes

In response to a recent reader comment about wide fluctuations in CO2 readings at Mauna Loa, Ralph Keeling and Stephen Walker of the Scripps CO2 Group gave the following answer: It’s fairly normal, especially in the summer time, to see strong afternoon “dips” in the CO2 concentration.  The dips are generally caused by upslope winds that that are depleted in … Read More

How are CO2 Data Processed?

Rob MonroeMeasurement Notes

Scientists make CO2 measurements in remote locations to obtain air that is representative of a large volume of Earth’s atmosphere and relatively free from local influences that could skew readings.