Final answer:
The size of Antarctica's b. ice cap fluctuates because it expands and shrinks with the seasons, not solely due to melting. This natural process is exacerbated by increasing global temperatures.
Step-by-step explanation:
The surface area of Antarctica fluctuates in size because the ice cap expands and shrinks with the seasons. During the Antarctic summer, temperatures rise and some of the ice may melt, leading to a decrease in surface area, while in the winter, colder temperatures cause the water to refreeze, thus increasing the ice cap's surface area again. This seasonal fluctuation of the ice cap is normal and part of the Earth's climatic rhythm.
Light-colored surfaces like snow and ice have high albedo, meaning they reflect a significant amount of solar radiation. If the Antarctic ice sheet were to melt significantly due to global warming, it would contribute to climate change by allowing the Earth's surface to absorb more radiation. The ice sheet in Antarctica is vast, holding about 70% of the Earth's fresh water, and the underlying large bodies of water would be exposed if melting occurred, affecting global sea levels and further altering the planetary albedo.
Seasonal changes also affect solar absorption, as described with Arctic ice caps. When these ice caps melt and expose darker water, solar absorption increases, leading to more melting. It's a feedback loop that has significant implications for climate change.