Climatologist: Global warming is affecting snowfall throughout the

D should be the answer. If the base amount is significantly high then even though the percentage lowered , still we may get a good amount of snow.

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­Percentage decrease doesn't always mean that the overall value is decreasing.

For "At this rate" trend to be true, the absolute value of snow precipitation in 2009 should be less than in 2004, otherwise it will break the conclusion. For example, let's say there was 100mm precipitation overall in 2004. This means 60% or 60mm was in the form of snow. Now, for 2009, let's consider two cases of precipitation: 1) 150mm and 2) 75mm. In the 1st case, 42% precipitation was in snow form, which is equal to 63mm. This is greater than 60mm snow precipitation in 2004, meaning that the author's conclusion about possible no snowfall in the next 20-30 years doesn't hold true. However, in the 2nd case, snow precipitation would be ~32mm, less than in 2004. Therefore, in order to not break author's conclusion, the 2009 snow precipitation should not be significantly greater than in 2004.

Hope this is clear.­

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Veritas Prep Official Explanation

D.

This question tests a data flaw that occurs commonly throughout the GMAT – just because the percentage that snow constitutes of the total precipitation has gone down DOES NOT mean that the actual volume of snowfall has gone down.

If overall precipitation has doubled, for example, then snowfall has gone up, from 60/100 to 84/200. D exposes this flaw – if you negate D it says “the volume of precipitation in 2009 was significantly greater than it was in 2004”, evidence that the total precipitation could well have dramatically increased.

Note the flaws in trap answers A and E – in A, the continued trend doesn’t need to be linear; in fact if it were exponential that would strengthen the conclusion even further.

And choice E actually does the opposite of D – if negated, E says “there was more rainfall in 2004 than in 2009”, showing that overall precipitation (and therefore snowfall) was way down in 2009.­