# Emily Judd Back to [[Topics/Climate Change Science and Policy Debate/Climate Change Science and Policy Debate|Climate Change Science and Policy Debate]] · [[Topics/Climate Change Science and Policy Debate/Research and Evidence|Research and Evidence]] **Role:** Paleoclimatologist; lead author of Judd et al. 2024, the 485-million-year temperature curve. - Led **Judd et al. 2024, "A 485-million-year history of Earth's surface temperature"**, *Science* 385(6715), [doi:10.1126/science.adk3705](https://doi.org/10.1126/science.adk3705). It combines proxy data with climate-model data assimilation (the PhanDA approach). - Affiliation at publication: University of Arizona and the Smithsonian National Museum of Natural History ⚠️ (from the Smithsonian release; current post not checked). - **Key findings:** global mean surface temperature ranged from ~11°C to ~36°C. The paper names CO₂ "the dominant control on variations in Phanerozoic global climate", with an apparent Earth-system sensitivity of ~8°C per CO₂ doubling. - **How Clack uses it:** he cites the paper's ~24°C average to argue today's ~15°C world is "historically cold" and warming is benign, and leaves out the paper's CO₂ conclusion. See the [[Users/@PeterDClack/Post Analyses/Post Analysis - PeterDClack on the Implausible 5.5C Scenario (2026-10-23)\|seed analysis]] and [[Users/@PeterDClack/Post Analyses/Post Analysis - PeterDClack on a Historically Cold World (2026-10-01)|Oct 1 analysis]]. - **Oct 23 chart (second use by Clack):** Willis Eschenbach's chart takes its temperature line from the PhanDA output CSV but its CO₂ bars from GEOCARB III (2001). PhanDA's own CO₂ columns in that same CSV peak at ~3,330 ppm (Early Ordovician) and give 624 ppm for the Hirnantian. A reply in the thread (@Ceist8) called the chart "dishonestly misrepresenting Judd et al". See the [[Users/@PeterDClack/Post Analyses/Post Analysis - PeterDClack on High-CO2 Epochs and Biodiversity (2026-10-23)|Oct 23 high-CO₂ epochs analysis]].