This heat map visualizes monthly global land-surface temperature anomalies from 1753 to 2015, with a base temperature of 8.66°C. Each cell represents a month and year, colored by temperature variance using a custom 14-color scale. The visualization is built with D3 v5, using `scaleTime` for axes, `scaleLinear` for color mapping, and SVG rectangles for rendering. Data is fetched from the FreeCodeCamp ProjectReferenceData JSON source, while the legend and axis labels are generated with `axisBottom` and `axisLeft`. The code includes commented-out tooltip logic, but no interactive tooltips are active in the final render.