A D3.js line chart compares global, northern, and southern hemisphere temperature anomalies from 1900 to 2023, using `d3.line` and `d3.scaleLinear` to render three colored series derived from CSV data. Below it, a combined chart overlays a blue line of global temperature on a bar chart of year-over-year change, with bars colored green or red based on positive or negative differences. Both charts use `d3.axisBottom`, `d3.axisLeft`, and `d3.scaleBand` for layout, rendered as SVG elements with custom styling.