HR: 08:00h
AN: B31D-01    [Abstracts]
TI: Ecosystem and Societal Consequences of Ocean versus Atmosphere Carbon Storage
AU: * Barry, J P
EM: barry@mbari.org
AF: James Barry, MBARI, Moss Landing, CA 95039 United States
AU: Adams, E E
EM: eeadams@mit.edu
AF: MIT, 77 Massachussetts Avenue, Cambridge, MA 02139-4307 United States
AU: Bleck, R
EM: bleck@rsmas.miami.edu
AF: Rosentiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149 United States
AU: Caldeira, K
EM: kcaldeira@globalecology.stanford.edu
AF: Carnegie Institution, 260 Panama Street, Stanford, CA 94305 United States
AU: Carman, K
EM: zocarm@lsu.edu
AF: Dept. of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803 United States
AU: Erickson, D
EM: ericksondj@ornl.gov
AF: Oak Ridge Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 United States
AU: Kennett, J P
EM: kennett@geol.ucsb.edu
AF: Dept. of Geological Sciences, UCSB, Santa Barbara, CA 93106 United States
AU: Sarmiento, J L
EM: jls@princeton.edu
AF: Princeton University, 306 Forrestal Campus, Sayre Hall, Princeton, NJ 08533 United States
AU: Tsouris, C
EM: tsourisc@ornl.gov
AF: Oak Ridge Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 United States
AB: Climate stabilization during the next 100 to 200 y will require significant reductions in atmospheric carbon dioxide emissions to avoid large increases in global temperature. While there is only mild disagreement concerning carbon management options such as energy efficiency, alternative energy sources, and even geologic C storage, ocean storage remains controversial, due to its potential impacts for deep-sea ecosystems. A cautionary approach to carbon management might avoid any ocean C storage. However, this approach does not consider the balance between ocean and terrestrial ecosystems, or societal concerns. Using a broader perspective, we might ask whether atmospheric CO₂ storage (i.e. the status quo), or deep ocean sequestration is better for Earth's ecosystems and societies? We explored the potential storage capacity of the deep ocean for carbon dioxide, under scenarios producing a 0.2 pH unit reduction, a level similar to observed scale of pH variability in deep ocean basins, which may also represent coarse thresholds for deep-sea ecosystem impacts. Roughly 500 PgC could be stored in the deep ocean to lower pH by 0.2 units, yielding a long term (~250 y) ocean sequestration program of 2 PgCy^-1. The mitigation value of such ocean C sequestration for upper ocean and terrestrial systems depends strongly on future emission scenarios. Under a low emission scenario (e.g. SRES scenario A1T, B1; atm CO₂ ~575 ppm, global temperature change of ~+2 ^oC), a 2 PgCy^-1 ocean CO₂ injection program could mitigate global temperature by ~-0.4 ^oC (20%) by 2100. This could reduce significantly the number of people at risk of water shortage and tropical diseases, with lesser improvement expected for hunger or coastal flooding. Mitigation for terrestrial and shallow ocean ecosystems is difficult to predict. A 0.4 ^oC reduction in warming this century is expected to delay the progression of coral reef devastation by roughly 20 y. The mitigation potential of ocean storage under very high emission scenarios appears weaker, due partially to uncertainty in the trajectories of ecosystem change and societal issues. For high emission scenarios (e.g. SRES A1F1, A2; 900 ppm CO2, 4.2 ^oC global temperature increase by 2100), the mitigation effect of ocean sequestration is still ~ -0.4 ^oC, with a reduction of atmospheric CO₂ near 50 ppm. However, under such high emissions, the effects of large global temperature on societal issues such as disease, hunger, and water are expected to be severe, with an unknown incremental benefit from ocean sequestration. These results indicate the importance of a careful consideration of the benefits and liabilities of ocean sequestration, in terms of ecosystem health for global ecosystems and terrestrial concerns. A cautionary approach to ocean carbon sequestration in consideration of the global consequences of anthropogenic climate change may differ from an approach considering deep-ocean ecosystems alone.
DE: 1630 Impacts of global change (1225)
DE: 1694 Instruments and techniques
DE: 6620 Science policy (0485)
SC: Biogeosciences [B]
MN: Fall Meeting 2005