CO2 rose every single year

The annual mean climbed from 315.8 ppm in 1959 to 363.8 ppm in 1997: up 48.0 ppm, or 15.2%, with no down year. Drag the slider to zoom in.

Remove the climb and the breath appears

On average, CO2 peaks in May and bottoms out in October, about 6.3 ppm apart. The usual explanation is northern plants drawing it down in summer and releasing it in winter.

Same breath, higher every decade

The swing grew only from 5.6 ppm in the 1960s to 6.3 ppm in the 1990s, while the whole curve lifted 38.5 ppm. Press play to walk through each year.

The climb has outrun the breath

360.24 ppm Lowest month of 1997, above the peak of every year through 1993
1.6 times Annual pace, from 0.86 ppm a year in the 1960s to 1.38 in the 1990s
4.5 years Of 1990s growth to equal one full 6.3 ppm seasonal swing

Data and method

  • Data. R’s built-in co2 dataset: 468 monthly readings from Mauna Loa, 1959 to 1997, in parts per million. Source: Keeling and Whorf, Scripps Institution of Oceanography.
  • Known gaps. R’s documentation notes that February to April 1964 were missing and filled by linear interpolation. Scripps may have since revised values, so these may differ slightly from its current records.
  • Trend. A centred 12-month (2x12) moving average, undefined for the first and last six months, which is why the heatmap has blank corners.
  • Seasonal swing. The range of the average month-by-month gap between readings and that trend.
  • Decades. 1960s to 1990s only: 1959 has no decade of its own, and the 1990s cover 1990 to 1997. Annual pace is the mean year-on-year change in annual means.
  • Numbers. Every statistic in the prose is computed from the data when this deck is knitted.
  • Built with. R version 4.6.1 (2026-06-24 ucrt), plotly 4.12.1, rmarkdown 2.32.