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- Title
GCM characteristics explain the majority of uncertainty in projected 21st century terrestrial ecosystem carbon balance.
- Authors
Ahlström, A.; Lindström, J.; Rummukainen, M.; Smith, B.; Uvo, C. B.
- Abstract
One of the largest sources of uncertainties in modelling of the future global climate is the response of the terrestrial carbon cycle. Studies have shown that it is likely that the extant land sink of carbon will weaken in a warming climate. Should this happen, a larger portion of the annual carbon dioxide emissions will remain in the atmosphere, and further increase the global warming, which in turn may further weaken the land sink. We investigate the potential sensitivity of global terrestrial ecosystem carbon balance to differences in future climate simulated by four general circulation models (GCMs) under three different CO2 concentration scenarios. We find that the response in simulated carbon balance is more influenced by GCMs than CO2 concentration scenarios. Singular Value Decomposition (SVD) analysis of sea surface temperatures (SSTs) reveals differences in the GCMs SST variability leading to decreased tropical ecosystem productivity in two out of four GCMs. We extract parameters describing GCM characteristics by parameterizing a statistical replacement model mimicking the simulated carbon balance results. By sampling two GCM-specific parameters and global temperatures we create 60 new "artificial" GCMs and investigate the extent to which the GCM characteristics may explain the uncertainty in global carbon balance under future radiative forcing. Our analysis suggests that differences among GCMs in the representation of SST variability and ENSO and its effect on precipitation and temperature patterns explains the majority of the uncertainty in the future evolution of global terrestrial ecosystem carbon.
- Subjects
GENERAL circulation model; UNCERTAINTY (Information theory); BIOTIC communities; CARBON cycle; MATHEMATICAL models; ATMOSPHERIC temperature; TWENTY-first century
- Publication
Biogeosciences Discussions, 2012, Vol 9, Issue 10, p13685
- ISSN
1810-6277
- Publication type
Article
- DOI
10.5194/bgd-9-13685-2012