This pie chart visualizes global emissions by gas type using data from the OWID CO2 dataset. The visualization displays proportional slices for each gas category, with a legend mapping color-coded segments to their respective labels. The chart uses D3 v7's `d3.pie`, `d3.rollup`, and `d3.arc` APIs to compute and render the arcs, while `d3.scaleOrdinal` with `d3.schemeSet3` provides the categorical color palette. The SVG output includes interactive-free path elements with white stroke separators and centroid-positioned text labels for each gas type.