Note: I can't provide the reading and lecture for this essay, but I thought you might like to see the structure of the completed essay.
The reading and the lecture are both about iron fertilization, which is the introduction of iron into oceans in order to stimulate the bloom of plankton which absorbs carbon dioxide from the air. The author of the reading believes that this is not an effective way to halt global warming. The lecturer casts doubt on the claims made in the article. She thinks that iron fertilization is a very effective way to prevent this serious problem.
First of all, the author claims that plankton does not lock away as much carbon dioxide as has previously been assumed. The reading notes that previous estimates fall short of actual amounts that will be absorbed as a result of iron fertilization. This point is challenged by the lecturer. She says that the plankton does absorb a very significant amount of carbon dioxide. Furthermore, she points out that recent studies of the phenomenon have not been carried out for long enough to accurately measure how much dangerous CO2 can potentially be locked away within the plankton.
Secondly, the author states that the process of iron fertilization results in the formation of too many dangerous toxins. It is argued that that the toxins produced can lead to very harmful phenomena like red tides. This argument is rebutted by the lecturer. She suggests that the production of toxins is not a major problem. She elaborates on this by mentioning that when global warming is no longer a threat the process can be called off and we will not have to worry about toxins any more.
Finally, the author mentions that iron fertilization can have a negative effect on eco-systems. He is of the opinion that the presence of so much plankton will favor certain species which will disrupt naturally occurring food chains. The lecturer, on the other hand, feels that the problem of global warming is much more serious than that of disrupted eco-systems. She puts forth the idea that global warming is critical to the natural environment of the entire earth.