# Demetris Koutsoyiannis 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:** Hydrologist (National Technical University of Athens); argues the CO₂ rise is mainly natural. - Professor of hydrology at NTUA ⚠️ (current emeritus status not checked). Known for stochastic (Hurst-Kolmogorov) hydrology. - **Koutsoyiannis 2024, *Sci* 6(1):17** ([doi](https://doi.org/10.3390/sci6010017)): fits Keeling plots to Scripps stations, getting intercepts of −13.2/−13.3/−13.3/−12.9‰ (mean −13.2‰), and argues the added CO₂ is not mainly fossil. Cohler's paper builds on this. He still writes: "There is no question that δ¹³C has been decreasing." - His long-record "subperiod A" (1520–1898) covers CO₂ of only about 283→295 ppm, which is why it says little about sources. - Challenged by Arno Kleber's comment ([*Sci* 6(4):62](https://doi.org/10.3390/sci6040062)); Koutsoyiannis replied ([6(4):63](https://doi.org/10.3390/sci6040063)). - See the [[Users/@cohler/Post Analyses/Post Analysis - cohler on the Keeling Intercept and Fossil CO2 (2026-10-24)|Cohler seed analysis]], claims 5–6.