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imageThis region is characterized by a huge front in silicate, another nutrient needed by some species of phytoplankton. The lines on this slide represent distance, latitude, and low concentrations of silicate north of the convergence zone, and high concentrations south. It's right at this interface that we find this bloom and fluorescence and this decrease in nitrate.

But we believe that there are fundamental differences in phytoplankton response to added iron, both north of the fronts and south of the fronts.

imageThese curves represent enrichment experiments performed in bottles with added, iron and measured chlorophyll concentrations. Also represented are the phytoplankton responses south of the polar front zone in high silicate area, and the response north of the front where there is low silicate. So the silicate concentration is going to have a dramatic effect on export from these two regions.

imageMajor scientific questions remain. Does iron enrichment result in the export of carbon? We think yes, in the Equatorial Pacific, and I think the jury is still out with respect to the Southern Ocean.
What were the temporal and spatial scales of transport, remineralization and sequestration of carbon in the deep ocean? We don't know the answer. What were the biogeochemical consequences of iron fertilization? In every case in the Equatorial Pacific, we see Nitzchia species coming up as the dominant diatom, which can form toxic blooms under certain environmental conditions.

Other problems mentioned today are the production of nitrous oxide or methane in the deep waters, and the potential for denitrification. What are the proxies for carbon sequestration? Finally, I'd like to briefly discuss some of the nonscientific questions.

imageThis slide is from 1998 and there is already a decrease in the human growth rate in the developing countries but a dramatic increase in developing country populations. This increase will result in even more dramatic concentrations of atmospheric CO2.

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imageAlso note the atmospheric response to increasing CO2 over the last 40 years as measured on top of Mauna Loa on the island of Hawaii.

 

A recent intergovernmental panel on climate change image(IPCC) has unveiled seven computer model scenarios that extrapolate global climate temperature to 2001, and every one of these scenarios has major environmental impacts.

Even at the lowest end of these model extrapolations, we're looking at substantial risks to many threatened species and serious climate events over the next few years.

imageThese scenarios have catapulted the discussion from the scientists into the public forum, which is why we're here today. A recent issue of Time magazine noted that except for nuclear war or collision with an asteroid, no course has more potential to damage our planet's balance of life than global warming.

imageSo I think oceanographers have been forced to examine this dilemma in a societal context, and to address some of these issues.

I believe societal and financial pressures to mitigate atmospheric CO2 will rapidly lead to action, but the question we have is what form should this action take? What shall be the role of the oceans? Is iron fertilization to control atmospheric carbon dioxide an appropriate use of the ocean commons? Should the trading of carbon credits be implemented and, if so, who should benefit? And should iron fertilization imageproceed prior to full implementation of other carbon mitigation measures, including conservation, alternative fuels, and reduction in population?

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