This chart reproduces the Keeling Curve, a time series that visualizes atmospheric CO2 concentration over time, plotting a single line that traces the annual sawtooth pattern of rising carbon dioxide levels. The data is sourced from the NOAA Global Monitoring Laboratory, though the dataset used here contains religious demographics with a date field parsed from year and month. The visualization is built with D3 v7, using `d3.scaleTime` and `d3.scaleLinear` for axes, `d3.line` for the path generator, and `d3.timeParse` for date parsing. A custom `axes` module renders the left and bottom axis labels.