PICE Talk by Mauro Rubino, Università “Luigi Vanvitelli”

Title: Sensitivity of the terrestrial Carbon cycle to temperature during the Little Ice Age

In this seminar, I will introduce the laboratories where I work and the general type of research I do. Then I will describe the results of my past research on paleo-Carbon cycle/climate feedback. Specifically, I will talk about how we have used the low atmospheric carbon dioxide (CO2) concentration during the Little Ice Age to derive the global land carbon cycle sensitivity to temperature. While it was well known that the low CO2 was caused by increased terrestrial carbon storage, it remained unknown whether the terrestrial biosphere responded to temperature variations, or there was vegetation re-growth on abandoned farmland. We have run a global numerical simulation of atmospheric carbonyl sulfide (COS) concentrations in the pre-industrial period. COS concentration is linked to changes in gross primary production and shows a positive anomaly during the Little Ice Age. I will show that a decrease in gross primary production and a larger decrease in ecosystem respiration is the most likely explanation for the decrease in atmospheric CO2 and increase in atmospheric COS concentrations. Therefore, temperature change, not vegetation re-growth, was the main cause of the increased terrestrial carbon storage. We have also addressed the inconsistency between ice-core CO2 records from different sites measuring CO2 and δ13CO2 in ice from Dronning Maud Land (Antarctica). Our interpretation allows us to derive the temperature sensitivity of pre-industrial CO2 fluxes for the terrestrial biosphere (γL = −10 to −90 Pg C K−1), implying a positive climate feedback and providing a benchmark to reduce model uncertainties.

Mauro Rubino
Department of Maths and Physics
Università degli Studi della Campania “Luigi Vanvitelli”

Mauro Rubino likes to be defined as an isotope biogeoscientist. He uses mainly isotopic techniques to quantify pools and fluxes of the biogeochemical cycles, with special regard to the carbon cycle. Mauro has got his PhD at the University of Campania (former Second University of Naples) and has worked in different research Institutions and Universities around the world (INRA – France, University of Copenhagen, CSIRO – Australia, Keele University – UK). He has published 32 articles, some of which are very well cited. He works now as an Associate Professor at the Department of Maths and Physics at University of Campania and he teaches Environmental Physics. He is the father of two beautiful girls aged 3 and 5. Every now and then he enjoys playing piano with his old friends.