Scientist: Earth's average annual temperature has increased by about

Thanks for the reply Is option C not an alternate cause ? Hence it should weaken ?

Ok , lets try it once again -

Premises : Buildup of minor gases in the atmosphere ===>Blocking the outward flow of heat from the planet ===>Warming the planet Conclusion : Earth’s average annual temperature has increased by about 0.5 degrees Celsius over the last century.

Powerscore Cr states that the correct answer to Weaken a question will -



Here option (D) attacke the premises/logic

Warming occurred (1939) =====>Buildup of minor gases in the atmosphere ( 1941 )

Whereas option (C) states -

Over the last century, Earth received slightly more solar radiation in certain years than it did in others.

Lets accept for the time being that yes the earth received more solar radiation in certain year than in other years , then ?

What role does it have in rising the temperature of the earth ? Does more solar radiation result it rising the temperature of the earth ? There is no relation stated here in the option which states that more solar radiation results in increasing the earth's temperature...

If you go further -

More Solar Radiation ------> Rise in temperature of the earth ( Assumption : Solar Radiation is related to temperature )

That will be far fetched, so we can negate option (C)

How does the fluctuation of radiation during a period of time have any impact on the rise in temperature during that period?

Here option (C) presesnts and alternate cause for increase in earth's temperature -



Diagrammatically it can be represented as below -



However option (C) presents a different reason altogether for the rise in temperature as below -



Here we are stating that the more solar the radiation the greater the temperature....

Hope this helps !!

Simple question of Cause and Effect.

Cause: buildup of minor gases
Effect: warming

In order to weaken this, I can say any one of the following

1. Warming was because of some other cause. (Alternate Cause for the effect)
2. Warming happens before buildup of minor gases. ( Effect happened before cause)
3. Both cause and effect happened at the same time.

Scanning through the options, only option B tells us what we are thinking. Hence, I dont bother about other options when I got what I am thinking.

Hence, B is the correct answer.

Scientist: Earth’s average annual temperature has increased by about 0.5 degrees Celsius over the last century. This warming is primarily the result of the buildup of minor gases in the atmosphere, blocking the outward flow of heat from the planet.

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

Analysis: weaken the argument
Cause ---------------------------------------------------> effect
blocking of the outward heat flow by the minor gases --> temperature increase 0.5C
weakener: if cause happens after the effect

(A) Only some of the minor gases whose presence in the atmosphere allegedly resulted in the phenomenon described by the scientist were produced by industrial pollution. --> what is cause of the cause doesn't weaken the conclusion

(B) Most of the warming occurred before 1940, while most of the buildup of minor gases in the atmosphere occurred after 1940. --> correct: cause happens after the effect

(C) Over the last century, Earth received slightly more solar radiation in certain years than it did in others. --> so what, it may emit more heat from the earth also

(D) Volcanic dust and other particles in the atmosphere reflect much of the Sun’s radiation back into space before it can reach Earth’s surface. --> this is trying to say that Earth's temperature should not increase

(E) The accumulation of minor gases in the atmosphere has been greater over the last century than at any other time in Earth’s history. --> gases comparison w/ other century doesn't weaken the conclusion

­Cause:  Increase in average temperature
Effect:  Buildup of minor gases in the atmosphere --> blocks the outward flow of heat

Question: Evidence against the scientist’s explanation i.e. the effect mentioned above.

Approach: Any option that attacks the effect mentioned i.e. either states something against the build up of minor gases or something against the outward flow of heat or can break the correlation between this cause and effect relationship will be correct.

Now coming to the options:
A) Only some of the minor gases whose presence in the atmosphere allegedly resulted in the phenomenon described by the scientist were produced by industrial pollution.-- Does nothing to undermine the mentioned effect or break the relationship.

B) Most of the warming occurred before 1940, while most of the buildup of minor gases in the atmosphere occurred after 1940.-- Breaks the realtionship directly as most of the warming( Cause) is happening before most of minor gas buildup( Effect) as mentioned in the passage. Hence the correct answer choice as the mentioned effect cannot be the right explanation for the cause.

C) Over the last century, Earth received slightly more solar radiation in certain years than it did in others.-- Does nothing to undermine the mentioned effect or break the relationship.

(D) Volcanic dust and other particles in the atmosphere reflect much of the Sun’s radiation back into space before it can reach Earth’s surface.-- Does nothing to undermine the mentioned effect or break the relationship.

(E) The accumulation of minor gases in the atmosphere has been greater over the last century than at any other time in Earth’s history. -- Does nothing to undermine the mentioned effect or break the relationship. Infact strengthens the relationship.