MdM SEMINAR SERIES- "A long tale of CO2" by Prof. Andy Ridgwell

Title: “A long tale of CO2”

Speaker: Prof. Andy Ridgwell, University of California, Riverside

Date: Thursday, 25th January 2018

Time: 12 h

Place: Z/022- Z/023 ICTA-UAB

Abstract

CO2 emitted to the atmosphere suffers a complex fate, with multiple sinks operating on a wide range of time-scales, from months to a million years ('the long tail of CO2'). While most excess CO2 has the appearance of vanishing rather quickly, the combination of the non-linear radiative impact of CO2 on climate (where small CO2 residuals in the atmosphere drive a disproportionate warming) and the persistence of small residuals on 'geological' (10-100 thousand years) time-scales, has important implications for slow-response elements of the climate system such as ice sheets.

In this talk, I'll start by describing the different processes governing the removal of excess (anthropogenic) CO2 from the atmosphere as well as their respective time-scales. I'll illustrate (using numerical models) how the CO2 sinks 'saturate' and progressively become less efficient, the more total CO2 that is emitted. I'll discuss the implications of this for millennial-scale ice-sheet stability and future sea-level rise. I'll also illustrate (again ... yet more models!) the difficulties inherent in trying to 'accelerate' the natural CO2 sinks and why 'carbon dioxide removal' geoengineering is not a practical solution to the consequences of anthropogenic climate change. There is no happy ending in this talk.

Bio

Dr. Ridgwell writes computer models (‘bad computer games’) – numerical representations of the primary interactions of climate with atmospheric CO2, including the cycling of carbon, oxygen, and nutrients between land, ocean, and marine sediments. His main current project is developing an Earth system model based around a 3D ocean circulation model, somewhat ridiculously named ‘cGENIE’. He has previously applied cGENIE to a range of diverse questions and time intervals, from geological episodes of extreme glaciation and warming, and global-scale ocean anoxia, through understanding global biogeochemical cycling in the modern Earth system, to quantifying future marine impacts of fossil fuel CO2 emissions and the effectiveness (or otherwise) of geoengineering. Current cGENIE-based projects and interests revolve around simulating the co-evolution of marine plankton and their environment, and their ecological sensitivities to past climate perturbations and global environmental catastrophe and elucidating the role of weathering in regulating atmospheric CO2 and climate. He never sets foot in the lab.

 

This activity is funded by BIGSEA. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 682602)