# Heather Graven 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:** Atmospheric scientist, Imperial College London; isotope expert. - Lead author of **Graven, Keeling & Rogelj 2020**, "Changes to carbon isotopes in atmospheric CO₂ over the Industrial Era and into the future", *Global Biogeochemical Cycles* ([doi](https://doi.org/10.1029/2019GB006170); [open access](https://pmc.ncbi.nlm.nih.gov/articles/PMC7757245/)). Co-author Ralph Keeling directs the Scripps CO₂ and O₂ programs. - Key statements: δ¹³CO₂ fell from −6.6‰ (1850) to −8.4‰ (2015); exchange with land and ocean produces "disequilibrium fluxes" that "partly counteract the decline in atmospheric δ¹³CO₂"; the Δ¹⁴CO₂ decline is "now driven primarily by fossil fuel emissions". - See the [[Users/@cohler/Post Analyses/Post Analysis - cohler on the Keeling Intercept and Fossil CO2 (2026-10-24)|Cohler seed analysis]], claims 3, 6, 7 and 9.