A new study by the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) allows validating organic markers to quantify past primary productivity in the oceans, a key factor in the global marine carbon cycle. The research, carried out from the study of alkenones as a biomarker, puts an end to decades of scientific debate about the validity of these biogeochemical proxies in the reconstruction process of past climates. The finding, which has been published in the journal Proceedings of the National Academy of Sciences (PNAS), will represent an advance in the improvement of climate models that allow predicting the climate in the future.