Question: If you want to cook something quickly, you heat it from both sides. That's what's happening to the West Antarctic ice sheet . A new study reveals that the area under the ice sheet is far hotter than previously thought, fed by an unexpected flow of geothermal energy . While the CO2we send out heats the atmosphere above the continent, earth is melting us ice from below. If you were to drill deep at some place on the continents, you would find that the temperature increases about 25degC for every kilometer deep into the hole on average. Scientists call this the geothermal gradient . Until recently, no one had drilled deeply enough through the West Antarctic ice to determine the geothermal gradient underground. For the new study, researchers drilled all the way through the ice and into the mud. They found that the geothermal gradient was about 200degC, which is several times the global average on continents. Few predicted this result, although it had been showed that the earth below the West Antarctic ice is unusually hot. Even with the new discovery, though, we still don't know exactly where the heat is coming from. One interesting possibility is volcanoes, which are under the ice. As recently as 2013, scientists were still discovering volcanoes under the ice in the area, and there may be many more. Some people say that these volcanoes, rather than manmade climate change, are responsible for melting the area's ice. While it's true that heat coming from within the earth, including heat related to volcanoes, makes the melting faster, it is just one contributor to the loss of the West Antarctic ice sheet---not the main cause. Today's study could help us understand how the whole system, including global warming, is melting the ice. What's the main idea of the passage? A) The West Antarctic ice sheet is in danger. B) Researchers are trying to stop global warming. C) The West Antarctic ice sheet's melting will bring terrible consequences. D) It has been known how to stop the melting of the West Antarctic ice sheet.
Answer:
A