CLIMATE × TECHNOLOGY

Measuring the Air

1958 to 2016 CE

Phanerozoic · Cenozoic · Quaternary · Holocene · Meghalayan

One instrument on a Hawaiian volcano, read without interruption since 1958, turned an argument into a graph. Carbon dioxide climbs every year, and within each year it dips and rises again as the northern forests leaf out and shed their leaves: the planet breathing, drawn to scale. The annual mean passed 400 parts per million in 2016.

Why it matters

The figures everyone now quotes for the present rest on a record that had to be begun by hand, defended against funding cuts, and kept running for sixty years by people who could not know what it would show. The sawtooth is the part worth looking at twice: the vegetation of the whole northern hemisphere, visible as a wobble in one line.

Dating & uncertainty

The measurement began in 1958 on Mauna Loa and has not stopped. It comes from a single station, but the rise is not a local effect: Keeling's early readings already found one, small and persistent, in Antarctica. The annual mean passed 400 parts per million in 2015 and 2016, a level last seen several million years ago.

Sources

1. Keeling (1960), Tellus · The concentration and isotopic abundances of carbon dioxide in the atmosphere
2. Betts et al. (2016), Nature Climate Change · El Niño and a record CO2 rise

Earth history as one day

23:59:59.99871.3 ms before midnight

if Earth’s 4.54 billion years were compressed into a single day