The 3D globe colors a well-mixed shell and animates flux glyphs to show the seasonal breath; this 2D companion instead plots the same underlying equations directly as a scrolling chart, the way Charles Keeling's own Mauna Loa data is actually published, and adds a control the 3D version doesn't expose: seasonal amplitude — how many ppm the Northern Hemisphere's growing/dormant cycle swings by.
trend(t) = 315 + 0.85·t + 0.0126·t² (t = years since 1958)
seasonal(t) = A · cos(2π·(frac(t) − 0.29)) (A = seasonal amplitude, adjustable here)
CO₂(t) = trend(t) + seasonal(t)
- Seasonal amplitude — the real Mauna Loa record sits near 3.1 ppm; lower it to see what a mostly-ocean hemisphere's flatter swing would look like, or raise it to model a world with more land vegetation driving a bigger yearly drawdown.
- Trend rate of rise — the live derivative of the long-term trend, d(trend)/dt = 0.85 + 0.0252·t ppm/yr; it was under 1 ppm/yr in the 1960s and is over 2 ppm/yr today, which is itself part of the historical record.
- Breath dial — the small disc top-right recolors green while the sawtooth is falling (NH growing season absorbing carbon) and orange while it's rising (NH dormant season releasing it), independent of the chart's own color.
Real-world relevance: the Keeling Curve is one of the most important graphs in climate science — the first direct, continuous proof that human emissions were accumulating in the atmosphere rather than being fully absorbed by land and ocean.