This example shows the Keeling Curve of atmospheric CO2 concentrations over time, using a line chart to display monthly measurements from a CSV dataset. The visualization uses D3.js to load and parse the data, then renders an SVG line chart with linear scales for time and CO2 values. It applies `d3.axisBottom` and `d3.axisLeft` for labeled axes, and generates the line path using `d3.line` with a monotone curve. The chart includes a loading state and resizes to fit its container.