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Difficulty: EasyEvaluating the Impact of New Evidence

Early Martian Climate

Two scientists discuss the primary greenhouse gas responsible for keeping liquid water on Mars's surface billions of years ago.

Scientist 1
Early Mars was kept warm primarily by a thick atmosphere rich in carbon dioxide (CO2CO_2). Volcanic activity released vast amounts of CO2CO_2 and water vapor, creating a strong greenhouse effect that maintained temperatures above freezing.

Scientist 2
Early Mars was kept warm primarily by methane (CH4CH_4) gas. Although CO2CO_2 was present, it was not abundant enough to prevent freezing. Instead, specialized early microbes produced methane, which is a much more potent greenhouse gas than CO2CO_2.

New Evidence
A rover analyzes ancient Martian sedimentary rocks and discovers large deposits of carbonate minerals, which form readily in the presence of high atmospheric CO2CO_2 levels. However, the rover finds no organic biomarkers or chemical signatures of methane-producing microbes.

Based on this new evidence, which of the following statements best describes the impact of this discovery on the scientists' viewpoints?

  1. The discovery of carbonate deposits and the absence of methane signatures support Scientist 1's viewpoint while weakening Scientist 2's viewpoint.Answer
  2. B
    The discovery of carbonate deposits and the absence of methane signatures weaken Scientist 1's viewpoint while supporting Scientist 2's viewpoint.
  3. C
    The presence of carbonate deposits and the lack of microbial signatures support both Scientist 1's and Scientist 2's viewpoints.
  4. D
    The new evidence has no effect on either Scientist 1's or Scientist 2's viewpoint.

Answer

The discovery of carbonate deposits and the absence of methane signatures support Scientist 1's viewpoint while weakening Scientist 2's viewpoint.
The discovery of carbonate minerals points to a high CO2CO_2 environment, which matches the atmospheric composition proposed by Scientist 1. Meanwhile, the lack of microbial biomarkers fails to provide the expected evidence for Scientist 2's microbe-produced methane model, thereby weakening that viewpoint.

Step-by-Step Solution

1
Analyze Scientist 1's core claim.
Scientist 1 claims CO2CO_2 from volcanoes was the primary warming gas.
To evaluate the impact of the new evidence, we must first understand what each scientist predicts.
2
Analyze Scientist 2's core claim.
Scientist 2 claims microbial methane (CH4CH_4) was the primary warming gas.
To compare the predictions, we need the central premise of both arguments.
3
Evaluate the new evidence against both claims.
Carbonate minerals support Scientist 1's high CO2CO_2 claim. The lack of microbial signatures contradicts Scientist 2's microbial methane claim.
Matching the findings to each claim reveals that the evidence supports Scientist 1 and weakens Scientist 2.

Key Concept

Evaluating the Impact of New Evidence
Estimated Time:1m 0s
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Topics

Evaluating the Impact of New Evidence

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