Logical Reasoning

PT140 · S1 · Q12 Climatologist: Over the coming century (copy)

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Climatologist: Over the coming century, winter temperatures are likely to increase in the Rocky Mountains due to global warming.

Conclusion

The mountain snowpack will probably melt more quickly and earlier, leading to greater spring flooding and less storable water for summer.

Evidence

The winter temperatures are likely to increase, causing more precipitation to fall as rain instead of snow.

Evaluate

Tall mountains usually receive a lot of snowfall over a winter, and the "snowpack" is basically the accumulated height of that snow. In the spring, that snow starts to thaw, sending pristine fresh water tricking down all the mountain streams.

The author is thinking that warmer winters will bring less snow (it won't be cold enough for snow, so the precipitation will fall as rain). Hence, the snowpack will be smaller.

Maybe in previous years, the snowpack was 10 ft deep, and now it'll be like 6 feet deep.

Why will it melt earlier? Well, if the winter temperatures are warmer then it's probably the case that we reach the thawing / melting temperatures of spring earlier, too.

Why will it melt more rapidly? This is probably just referring to 6 ft vs. 10 ft, the idea that once temperatures rise enough to start the thawing / melting process, it will take less time to melt 6 ft than it will 10 ft. (We might also plug in outside knowledge that the thicker the snowpack is, the more it self insulates, kind of like the way the deeper water in a swimming pool will stay colder than the shallow water)

Why will there be more spring flooding? Well, floods come from a rapid increase of water, so the author must be thinking that because the snow will melt more rapidly, there will be more floods.

Why will there be less storable water? If there's only 6 ft of snow vs. 10 ft., then that's less water. I guess I'm confused though why the extra rain doesn't make up for it. I don't really understand where storable water comes from (is it gathered more easily from melting snow than from rain?)

Yeesh, what an exhausting argument to try to unpack and understand.

If we were trying to think of potential objections, we'd pull out our Comparison + Prediction toolbox and think,

Goal

Look for an answer strengthening the causal story the author is selling us or one that rules out an objection that would keep her prediction from coming true.

12.

Which one of the following, if true, most strengthens the climatologist's argument?

Global warming will probably cause
Weakens
If there is a lot more precipitation, then even though a smaller proportion falls as snow, there still might be just as much snow as before. i.e. maybe the precipitation used to be 50% snow, 50% rain, and global warming will change that to be 40% snow, 60% rain, but 40% of a bigger number can still be at least as big as 50% of a smaller number.
12% picked this
Correct
In other mountainous regions after
Why this is right
This is a "More Cause, More Effect" plausibility strengthener for the author's prediction. It provides data points showing that in other areas, the supposed cause (warming temps in a mountainous region) led to some of the predicted effects (the melting caused greater spring flooding and less storable water). This doesn't address the "melting more rapidly / earlier" part of the prediction, but a Strengthen answer doesn't have to be perfect. It just has to beat the other answers.
Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.
52% picked this
On average, in areas of
Too Weak
This answer ends up going head-to-head with (B), for a lot of us. It also has the feel of More Cause / More Effect data points: It's associating the supposed cause (relatively mild winters) with some of the predicted effect (less storable water). But it's just not as strong a strengthener as (B). They both deal with the concept of milder vs. colder winters. (B) deals with entire mountainous regions changing from colder to milder. (C) deals with individual patches within a mountainous regions being colder vs. milder. (B) wins that battle, since the author's argument is about an entire mountain region changing from one climate to another. (B)'s match for the predicted effects is "melting snowpack led to more spring flooding and less storable water" (C)'s match for the predicted effects is just "less storable water". So (B) wins that battle too, since it deals with spring flooding and since it deals with the causal idea that melting snowpack led to these changes.
26% picked this
On average, in the regions
Too Weak
Like (B) and (C), this answer has some elements of More Cause / More Effect data points. But this answer deals with outliers (regions with the mildest winters) rather than a change (regions that went from colder to milder winters). And this answer doesn't include any of the causal connection between melting snowpacks and more flooding / less storable water.
6% picked this
The larger a mountain snowpack
Weakens
The author's story actually involves a smaller snowpack (since a shrinking % of precipitation ends up being snow) leading to greater spring flooding. So this answer would Weaken the argument.
4% picked this

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