#23 - The effects of global warming on the polar ice caps

[Administrator]

Please post your questions below! Thank you!

[theamazingrace]

I was stuck between answer choices A and B but ultimately chose A. I believe A is correct because it talks about snowfall which would increase the size/volume of an ice cap that was melted considerably like mentioned in the stimulus while answer choice B says that the ice cap would be stabilized in size. So, the size/volume of the ice cap is not getting bigger or shrinking it’s just staying the same. Is my reasoning correct?

Thanks

[KelseyWoods]

Hi theamazinggrace!

Yes, your reasoning is basically correct. The paradox here is that the models show that the increase in global temperature is going to raise sea temperature and melt the ice caps, yet the overall volume of the ice caps is going to increase. So we're looking for an answer choice that explains how the overall volume of the ice caps could increase even though the rise in temperature is causing them to melt. Answer choice (A) does this by telling us that even though the ice caps may be melting considerably, there will also be increased snowfall which will add to the volume of the ice caps. Answer choice (B), on the other hand, seems to be trying to discount one side of the paradox above. We know from the stimulus that the rise in temperature will raise sea temperature and will melt the ice caps. We have to accept that as true. We do not want an answer choice that tries to argue with that fact. Answer choice (B) tries to argue with that fact by saying that the sea temperature might be warmer, but the water will be in less contact with the ice caps, suggesting it would not melt the ice caps. Again, we know from the stimulus that the ice caps will melt. So what we really need is a way for volume to be added to the ice caps to make up for this melting that will occur so that the overall volume of the ice caps increases. In Resolve questions, we need an answer choice that allows both sides of the paradox to be true. So the big problem with answer choice (B) is that it goes against one of the facts above by suggesting that the sea water will not be melting the ice caps, and it does not give us anything to explain why the volume of the ice caps would actually increase.

Hope this helps!

Best,
Kelsey

[hannahs]

Can you explain why answer choice D is wrong? I thought D explained the paradox. If the freezing temperature increases as sea temperature goes up, wouldn't this suggest that the ice caps could potentially re-freeze and maybe even more sea water could freeze to become ice caps?

[KelseyWoods]

Hi Hannah!

Answer choice (D) states that "As sea temperatures increase, evaporation of seawater causes the concentration of salt in the water to increase, which thereby lowers the temperature needed to freeze the seawater." Notice that it states that the higher sea temperatures would decrease the freezing temperature of the saltwater, not increase it. Thus, answer choice (D) makes the paradox even more perplexing because it's saying that it would be more difficult for the seawater to freeze because it needs to be at an even lower temperature than it previously needed to be at in order to freeze.

Hope this helps!

Best,
Kelsey