Chapman Conference on
in Driving Global Climate Change, Past and Future
24 – 27 July 2005
Registration and Information
The Climate Institute - Woods Hole Oceanographic Institution
National Science Foundation
National Oceanic and Atmospheric Administration
National Academy of Sciences
The purpose of the meeting is to explore the climate change potential of variations in the rain ratio of marine organic carbon to CaCO3 through the oceanic water column and to the sea floor. The rain ratio in the water column affects the strength of the biological carbon pump in the oceans and thus, the marine carbon cycle. Upper ocean studies indicate that the organic carbon to calcite flux ratio in the water column might respond to future anthropogenic climate change. Additionally, climate may feedback on oceanic fluxes by altering marine calcification rates. Finally, the rain ratio to the sea floor is thought to control the pH of the ocean and the pCO3 of the atmosphere, on time scales of thousands of years, by altering the dynamics of the CaCO3 cycle. The goal of the meeting is to assess the potential variability of the rain ratio, and the status of modeling efforts aimed at predicting particle fluxes under different climatic regimes, both past and future.
What do models tell us about the potential climate role of the oceanic organic carbon to calcite rain ratio? Factors which may influence the balance between organic carbon and CaCO3 export from the ocean's surface layer include temperature, water column stratification / productivity, silica concentration, and pCO3 (affecting calcification). How well grounded are these sensitivities observationally, and what is the most appropriate to model them?
The rain ratio of the particles that reach the abyss may depend on the physics of sinking particles, in that sediment trap particles are found to be more ballast-rich than what is produced at the surface. Perhaps organic carbon dissolves more quickly than CaCO3, until a particle is sufficiently ballasted to sink. Or perhaps only particles with the appropriate ballast ratios are selected to sink; the rest degrade at the surface. A mechanism such as one of these might tend to limit the variability of the rain ratio to the abyss and to the sea floor. Models of particle coagulation/sinking neglect ballast; models of ballasting do not explain the high flux of organic particles in the upper water column (dubbed "free poc"). Can we develop a particle 'theory' that accounts for all observations and whose implications concerning rain ratio change can be tested independently?
The ocean's sediments contain a record of the variability of the rain ratio in relation to climate change. Do we have the tools to recover the rain ratio signal? What does the sediment record reveal concerning rain ratio changes? Additionally, the rain ratio to the sea floor may be affected at least locally by sediment focusing, but it is unclear how focusing affects the rain ratio. One possibility is that the particles are focused in the water column. This would seem to be consistent with the equatorial signature of focusing during LGM, but it would be inconsistent with the observation from traps that thorium falls straight down, with no focusing to be found. What would LGM sediment traps have shown? When thorium is focused, does organic carbon focus with it, or not? What affect does focusing have on the preservation of CaCO3 and on our ability to reconstruct past rain ratios?
The Conference Objective is to explore modeling approaches in terms of what observations now reveal about processes governing the fluxes. Opinions on the potential variability of the flux ratio are 'vertically stratified'. Work by plankton ecologists and modelers reveal mechanisms of variability and climate sensitivity. Analysis of sediment trap data favors ratio invariance. CaCO3 preservation modeling shows evidence of flux ratio changes in the past, during LGM and perhaps PETM. We plan to examine the discrepancies and develop an understanding of what advances are needed to successfully evaluate past and future flux changes and the impact of these on global climate. Participants in the conference will contribute to synthesis and 'state of the art' publications providing the general oceanographic/climate communities with overviews of our knowledge concerning flux variability and global change.
Since the early 1980s biogenic fluxes of organic matter and calcite from the surface ocean to the deep sea have been implicated in regulation of atmospheric carbon dioxide content (and Greenhouse warming). General consensus exists that one of the key marine biotic climate variables is the ratio of organic carbon to calcite fluxes from the surface to the deep ocean, which can alter the pH and alkalinity of seawater and thus the pCO3 of the atmosphere. However, there is disagreement on the potential magnitude of effect that changing this ratio would have on atmospheric CO3, and there is disagreement on the degree to which the ratio can change. Further, there are many questions concerning the processes that regulate both fluxes and their ratio. So, we are at a point where, for example, some modeling work indicates that changes in the marine organic carbon to calcite flux ratio could account for nearly all the substantial change in atmospheric carbon dioxide content observed between the last full glacial and the present); while other work suggests that the flux ratio is relatively stable and therefore would not account for a significant fraction of past natural variations in atmospheric carbon dioxide content.
The issues surrounding the biogenic fluxes to the deep ocean are also critical in the response of climate to anthropogenic forcing. Future changes in the carbon cycle that may affect air-sea partitioning of CO3 are difficult to quantify but paleoceanographic and modern observational studies provide important evidence concerning what variations might occur. Future surface ocean acidity increases will affect the production and export of CaCO3, and thereby potentially the export and sedimentation fluxes of organic carbon as well. The degree to which this happens, and the response of oceanic biogeochemical cycles, will influence longer term changes in atmospheric pCO3.
Clearly, understanding the processes controlling the transport of organic carbon and calcite through the water column is essential to complete modeling of global climate change; both in the past and in the future. However, scant attention has been given to the underlying mechanisms governing POC and carbonate remineralization/dissolution, especially in the water column. As these mechanisms ultimately determine the deeper ocean fluxes of both organic carbon and calcium carbonate, a more quantitative treatment may shed light on additional important feedbacks within the global carbon cycle. Understanding processes and feedbacks is not only important in relation to control of CO3 in the atmosphere, but also in understanding the response of marine ecosystems to past and future environmental change.
The purpose of this Chapman Conference is to assemble marine chemists, geochemists, biologists, paleoceanographers and climate/geochemical modelers with an interest in determining the role of biological production and biogenic fluxes in regulating global climate change. The objective of the conference is to provide a forum for communication among scientists examining modern processes of biogenic flux production and transfer to the deep sea, its geological record and its modeled role in the climate system.
See the Daily Schedule [53KB PDF]
Applications are being made to several U.S. agencies to support travel of conference participants. Graduate students and young scientists will receive priority for funding. The date for travel fund application has past.
Registration Deadline has past.
Sleeping rooms have been blocked at two hotels that are within walking distance of Woods Hole Oceanographic Institute. The cut off date to make a reservation for both hotels is June 23, 2005.
Inn on the Square is holding rooms from July 23-28, 2005. The rates are $129/single double and $10 for each additional person. To make your reservations, please call +1-800-676-0000 and identify that you are with the Chapman Conference.
Nautilus Motor Inn is also holding a block of rooms from July 23-28, 2005. The rates are $121/single or double Sunday through Thursday and $138/single or double Friday and Saturday. Reservations can be made by calling +1 (800) 654-2333 or emailing firstname.lastname@example.org. More information about this hotel can be found on their website, http://www.nautilusinn.com.
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