# Florian Böhm 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:** Geochemist (GEOMAR, Kiel); sclerosponge δ¹³C records. - Lead author of **Böhm et al. 2002**, "Evidence for preindustrial variations in the marine surface water carbonate system from coralline sponges", *Geochemistry, Geophysics, Geosystems* ([doi](https://doi.org/10.1029/2001GC000264)) ⚠️ (title from memory; DOI checked). - Cohler cites the sponge record as showing no drift back to 1500 AD. The paper says the opposite for the industrial era: the records "clearly reflect the industrial ¹²C increase" and "show the full extent of the industrial decline… caused by the anthropogenic addition of ¹²C-enriched CO₂." Preindustrial variation was only about ±0.07‰. - Its atmospheric comparison curve is "derived from Antarctic ice core, firn air inclusions and air measurements", so it is not independent of Law Dome. See the [[Users/@cohler/Post Analyses/Post Analysis - cohler on the Keeling Intercept and Fossil CO2 (2026-10-24)|Cohler seed analysis]], claim 5.