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Chlorophyll, Plankton and global warming


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Phytoplanktons are a small species of plant that are distributed unevenly across the oceans surface, which play an important role in recycling much of the earth’s carbon dioxide, and so scientists wondered around a decade ago whether by increasing the number of these plants could be used to control global warming. Even in areas where nutrients are rich, the plants are not found. This is most likely because of a lack of iron in many of these areas. Tests in laboratories attempted to find whether if iron was the missing nutrient, but with so many variables to control, this theory could only be tested by releasing a vast quantity of iron sulphate into the sea, along with a radioactive tracer, sulphur Hexafluoride. Oceanographers traced the currents to track their progress along the food chain.


Beyond this, scientists surveyed the plankton from the air. If you illuminate chloroplasts strongly, the light which cannot be used is reflected back. Lasers aimed at the sea measured the levels of Chlorophyll, (presumably of Phytoplankton) in the sea, and within 2 days, a very rapid increase in the number of phytoplankton was recorded where the iron had been added. Unfortunately, this proved very short lived, either because the Iron dropped to depths too deep to be of any use to the plankton, or perhaps the animal plankton grew rapidly too, taking advantage of the feast available.


So far, scientists have not been able to explain results.


Has any progress been made on this subject?

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You are describing part of the process by which chalk and other sedimentary rocks are produced. Unfortunately the next part is that almost all of the carbon in these dead organisms is respired by other organisms or dissolves. It re-enters the carbon cycle instead of becoming rock. This is why rock formation is incredibly slow. Unless we could find a way to change the process, it would do little against climate change.


One also has to question the sustainability of the proposal. Where to keep on finding and funding all those tonnes of iron? What other processes will be disturbed? E.g. it would be an even bigger disaster than we have already if actions bring carbon out of dissolution at ocean depths and up to the surface. What side effects are possible? E.g. the toxic red algal bloom that followed a natural dust storm laden with iron and killed much sealife off Africa.


There are more promising ways to sequester carbon naturally. You might try the Terra Preta thread.



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One also has to question the sustainability of the proposal. Where to keep on finding and funding all those tonnes of iron? What other processes will be disturbed?


This technique is described well in the "DIY Planet Cooling" Thread. Good links to the original research. It is an interesting idea I had not seen before.

Most of Western Australia is iron. We could always send it to Japan and China in a slowly leaking ship??:)


DDT floats on the top micron of sea water-where most phytoplankton reproduce. It and other chlorinated hydrocarbons are interfering with phytoplankton's reproductive ability. If it gets severe this could be disastrous for all life on this watery planet.

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It is an interesting idea.

That being said, I think it would be far better to limit our impact on the bioshpere than to increase it until we know much much more about it.


Now, if it turns out that we have zero effect on the climate right now, obviously limiting our effect will have no... effect (record for using the same word in a sentance??) on GW. So in that case we would need to be more agressive.


That is why I like the idea of this type of research continuing, even if it isn't my first choice (or second or third) in fixing the issue.

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