Interactions between reducing CO2 emissions, CO2 removal and solar radiation management

TitleInteractions between reducing CO2 emissions, CO2 removal and solar radiation management
Publication TypeJournal Article
Year of Publication2012
AuthorsVaughan, N, Lenton, T
JournalPhilosophical Transactions of the Royal Society A
Volume370
Issue1974
Start Page4343
Pagination4343-4364
Keywordscarbon cycle–climate feedbacks, Carbon dioxide removal, Geoengineering, mitigation, solar radiation management
Abstract

We use a simple carbon cycle–climate model to investigate the interactions between a selection of idealized scenarios of mitigated carbon dioxide emissions, carbon dioxide removal (CDR) and solar radiation management (SRM). Two CO2 emissions trajectories differ by a 15-year delay in the start of mitigation activity. SRM is modelled as a reduction in incoming solar radiation that fully compensates the radiative forcing due to changes in atmospheric CO2 concentration. Two CDR scenarios remove 300 PgC by afforestation (added to vegetation and soil) or 1000 PgC by bioenergy with carbon capture and storage (removed from system). Our results show that delaying the start of mitigation activity could be very costly in terms of the CDR activity needed later to limit atmospheric CO2 concentration (and corresponding global warming) to a given level. Avoiding a 15-year delay in the start of mitigation activity is more effective at reducing atmospheric CO2 concentrations than all but the maximum type of CDR interventions. The effects of applying SRM and CDR together are additive, and this shows most clearly for atmospheric CO2 concentration. SRM causes a significant reduction in atmospheric CO2 concentration due to increased carbon storage by the terrestrial biosphere, especially soils. However, SRM has to be maintained for many centuries to avoid rapid increases in temperature and corresponding increases in atmospheric CO2 concentration due to loss of carbon from the land.