This sunburst chart visualizes global CO₂ emissions, grouped hierarchically by region and then by country. Each arc segment’s size and color (using a warm-to-cool gradient scale) represent the total emissions for that country. The chart is built with D3.js, using `d3.partition`, `d3.arc`, and `d3.hierarchy` to compute the layout from the grouped data. Hovering highlights a segment and temporarily displays its name and value in a text label.