Environmental Climate Change : The role of marine and aquatic photosynthetic organisms in the global carbon cycle
Raven, John A. , Thorhaug, Anitra .
Introduction to Climate change: the role of marine and inland water plants in inorganic carbon cycling and global environmental change.
95% of carbon in the biosphere is oceanic (38,000 giga tonnes or Gt). About 26% of anthropogenic carbon dioxide produced each year (8.5 Gt of carbon from fossil fuel and cement and 1.5 Gt from forest removal) are absorbed into the oceans; some 29% is removed by terrestrial vegetation uptake and sequestration, and 45% remains in the atmosphere, contributing to an increased greenhouse effect. Between 1800 and 1994 the total ocean uptake was 118 Gt, with a further 28 Gt up to 2007. Since 1800 this has decreased the pH of the oceans by 0.1 unit , with an increase in dissolved carbon dioxide, a smaller relative increase in bicarbonate, and a decrease in carbonate . A further decrease, by up to 0.5 pH units in total, is expected by 2100, limiting the future capacity for removal of anthropogenic carbon dioxide. These changes are expected to have differential effects on photosynthetic primary productivity by the range of photosynthetic organisms, as well as having differential effects on calcification by photosynthetic and other organisms. These predictions of variable effects of environmental change are related to the much greater phylogenetic diversity of aquatic primary producers than of embryophytic plants on land. It is vital that increased knowledge of inorganic carbon assimilation in aquatic systems is used to improve models of global biogeochemical cycles, and to inform suggestions about increasing carbon dioxide sequestration in the ocean. Calculations for the oceanic carbon sink include solution and carbonate buffered (‘solubility pump’) and sedimentation of particulate biogenic carbon (‘biological pump’) whereas the terrestrial carbon calculations focus chiefly on vegetation and soil. Oceanic sequestration studies need better estimates of assimilation, sequestration in long-lived species and biogenic additions to carbon sedimentation by plankton, macroalgae and embryophytic marine plants.
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1 - University of Dundee , Division of Environmental and Applied Biology, Biological Sciences Institute, Dundee DD1 , 4hn, Scotland, UK
2 - Yale University School of Forestry & Environmental Studies, 1359 SW 22 TER, Miami, Florida, 33145, USA
oceanic carbon cycling
oceanic carbon sequestration
biological carbon pump
biogenic carbon sediment
global biogeochemical cycles.
Presentation Type: Symposium or Colloquium Presentation
Location: Cottonwood B/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 8:30 AM