Logical Reasoning

PT123 · S2 · Q5 Scientist: Earth’s average annual

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Scientist: Earth’s average annual temperature has increased by about 0.5 degrees Celsius over the last century.

Curious Fact

Why has Earth’s average annual temperature increased by about 0.5 degrees Celsius over the last century?

Causal Explanation (the result of)

Minor gases build up in the atmosphere and block heat from flowing outward into space, making the Earth warmer.

Evaluate

Whenever we see "hypothesis" or "explanation" in the question stem, we know we're dealing with a causal argument in which the conclusion states or assumes some causal explanation for a funky phenomenon or statistic.

The two pressure points are 1. Alternate Explanations for the curious fact 2. the plausibility of the author's explanation

Goal

Let's look for an answer that suggests an Alternate Explanation for why Earth's average temp has gone up over the last century, or for an answer that makes it seem less plausible that the increase in heat is from minor gases' building up in the atmosphere and blocking heat from escaping into space.

5.

Which one of the following, if true, would count as evidence against the scientist's explanation of Earth's warming?

  1. Only some of the minor

    Out of Scope

    Whether or not the minor gases were produced by industrial pollution is not relevant to whether those gases caused an increase in the Earth’s average temperature.

    5% picked this

  2. Correct

    Most of the warming occurred

    Why this is right

    This undermines the argument by suggesting that effect occurred before the buildup of minor gases in the atmosphere. It hurts the plausibility of the author's explanation by showing Effect w/o Cause. The effect of warming was present prior to 1940, but the supposed Cause (the buildup of minor gases) was absent prior to 1940.

    Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

    63% picked this

  3. Over the last century, Earth

    Unclear Impact

    A potential Alternate Explanation for a warmer Earth over the past century could be, "it's receiving more solar radiation from the Sun". In other words, the warming isn't because heat from Earth increasingly can't escape back into space; the warming is because the Sun is just sending more radiation in the first place. But this answer doesn't say "over the last century, the Earth received more solar radiation than it did in the previous century". It's just saying in 1938 the Earth received slightly more solar radiation than it did in 1983 (for example). That would be true in any century. No one expects every year in a century to get identical amounts of solar radiation, so this answer can't be that impactful (it's saying something we already know from common sense). If we knew that "in the second half of the last century, Earth received more solar radiation than in the first half of the last century", then that could potentially be an alternate explanation for why the avg temp has increased over the last century. But as is, this answer is too weak and ambiguous to have impact.

    16% picked this

  4. Volcanic dust and other particles

    Unclear Impact

    This answer could strengthen or weaken the argument depending on whether there was a decrease or an increase in such particles over the last century.

    11% picked this

  5. The accumulation of minor gases

    Strengthens

    This supports the scientist’s explanation by correlating the buildup of minor gases with the increase in the Earth’s average temperature.

    6% picked this

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