Basically this line, from the caption of the 3rd line graph at the US climate.gov site[1] that shows large magnitude swings over long periods: > Global atmosph

Basically this line, from the caption of the 3rd line graph at the US climate.gov site[1] that shows large magnitude swings over long periods: > Global atmospheric carbon dioxide (CO2) in parts per million (ppm) for the past 800,000 years. The peaks and valleys track ice ages (low CO2) and warmer interglacials (higher CO2). Unfortunately, it continues: > During these cycles, CO2 was never higher than 300 ppm. The increase over the last 60 years is 100 times faster than previous natural increases. In fact, on the geologic time scale, the increase from the end of the last ice age to the present looks virtually instantaneous. (Note the last dot on the chart in the upper-right corner representing 2021's average value of 414.7 ppm. This corresponded to a time roughly 3 million years ago when ocean levels were 16 to 82 feet higher than today.) [1] https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide https://www.climate.gov/news-features/understanding-climate/...