1. Which of the following, if true, would most undermine the effectiveness of the proposed strategy described in the passage for counteracting the greenhouse effect?
Answer: A
The low population density of phytoplankton in the Southern Ocean being due to something other than an iron deficiency undermines the proposed strategy.
If the low population density of phytoplankton is caused by factors unrelated to iron deficiency, then fertilizing the Southern Ocean with iron may not effectively enhance phytoplankton growth or photosynthesis, thereby failing to counteract the greenhouse effect.
A) The low population density of phytoplankton in the Southern Ocean is due to something other than an iron deficiency.
This option directly challenges the foundation of the proposed strategy. If phytoplankton density is low due to reasons such as lack of light or other nutrient deficiencies, then iron fertilization would not address the root cause and would likely be ineffective in increasing carbon dioxide absorption.
B) The buildup of carbon dioxide in the Earth's atmosphere is caused by industrial rather than natural emissions.
While this statement provides insight into the sources of carbon dioxide, it does not impact the mechanism of iron fertilization itself. The proposed strategy could still be effective regardless of whether the carbon dioxide sources are natural or industrial.
C) There is a process capable of measuring the rate at which phytoplankton photosynthesize.
The existence of measurement processes does not influence the effectiveness of iron fertilization. It simply provides a means to monitor the potential outcomes of the strategy, rather than undermining its rationale.
D) New forms of single-celled plant life that rely on iron for photosynthesis have been detected.
This option could potentially support the strategy rather than undermine it. If new phytoplankton species that require iron are found, it may reinforce the need for iron fertilization to enhance their growth and photosynthetic activity.
E) Some carbon dioxide is regularly pulled out of the atmosphere through naturally occurring processes.
While this statement acknowledges natural carbon dioxide absorption, it does not negate the proposed strategy's potential effectiveness. The existence of natural processes does not diminish the possibility that enhanced phytoplankton photosynthesis through iron fertilization could also contribute positively.
Conclusion
In conclusion, option A is the only choice that directly challenges the basis of the iron fertilization strategy by suggesting that another factor, not iron deficiency, is responsible for low phytoplankton populations. The other options either provide additional context, suggest supportive scenarios, or do not relate directly to the efficacy of the proposed method, thus failing to undermine the strategy effectively.