Encounter 41 · 41 of 42 · March 1958
The curve
On 29 March 1958 an infrared analyzer at Mauna Loa recorded 313 parts per million of carbon dioxide. Charles David Keeling wanted a clean baseline. He did not know whether the station would be funded long enough to tell a trend from a season.
Mauna Loa Observatory, Hawaiʻi
What they knew
- On the first day of operation the analyzer read 313 parts per million.
- The instrument could resolve small changes, if it was kept calibrated.
- Funding for a measurement that looked like watching paint dry was always at risk.
What they could not know
- Whether a rise, if any, would continue.
- Whether a seasonal wiggle was noise.
- Whether the station would be funded long enough to tell.
The situation
Charles David Keeling, at Scripps, began continuous CO₂ measurements at Mauna Loa in March 1958, with International Geophysical Year funds and a Weather Bureau facility. Previous numbers had been scattered. He wanted a clean baseline. This plate is a measurement, a first day, not a night.
313 ppm
First day of operation, Mauna Loa, 29 March 1958. Scripps. Approximate later annual means are a different chair.
A motivational telling would make Keeling a prophet. He was a careful measurer. Most of his seniors thought such instruments cost more than anyone needed to watch a gas that fluctuated. IGY funds were large enough, and he was persuasive enough, to get the analyzer onto the mountain.
1958
The hut
313 ppm. A seasonal wiggle not yet named. A station that could still be shut.
Later
The line
He died in 2005. The record did not.Scripps and NOAA maintain the Mauna Loa series. Recognition of the curve is not the same as action. A later public argument is not spent backward into the first day.
This Guide will not sermonize the graph. The 1958 chair is a number, and whether anyone would keep taking it.
What was at stake
A dataset, a career, and a hut. In 1958, not a public argument about a planet.
The next move
He kept measuring.
What they had
- An infrared analyzer
- A mountain
- A stubbornness about calibration
- IGY money
What happened
The first months showed a seasonal breath of the northern forests on a number that did not sit still. The record did not yet have a name.
313 ppm. A station that could still be shut.
Private. No one else will see it.