A、They measured the depths of sea water. B、They analyzed the water content. C、They explored the ocean floor. D、They investigated

(19)Earlier this year, British explorer Pen Hadow and his team trekked for three months across the frozen Arctic Ocean, taking measurements and recording observations about the ice.
    "Well, we’d been led to believe that we would encounter a good proportion of this older, thicker, technically multi-year ice that’s been around for a few years and just gets thicker and thicker. We actually found there wasn’t any multi-year ice at all. "
     (20)Satellite observations and submarine surveys over the past few years had shown less ice in the polar region, but the recent measurements show the loss is more pronounced than previously thought.
    " We’re looking at roughly 80 percent loss of ice cover on the Arctic Ocean in 10 years, roughly 10 years, and 100 percent loss in nearly 20 years. "
     (21)Cambridge scientist Peter Wadhams, who’s been measuring and monitoring the Arctic since 1971 says the decline is irreversible.
    "The more you lose, the more open water is created, the more warming goes on in that open water during the summer, the less ice forms in the winter, the more melt there is the following summer. It becomes a breakdown process where everything ends up accelerating until it’s all gone. "
    Martin Sommerkorn runs the Arctic program for the environmental charity—the World Wildlife Fund.
    "The Arctic sea ice holds a central position in the Earth’s climate system and it’s deteriorating faster than expected. Actually, it has to translate into more urgency to deal with the climate change problem and reduce emissions. "
    Summerkorn says a plan to reduce greenhouse gas emissions blamed for global warming needs to come out of the Copenhagen Climate Change Summit in December.
    " We have to basically achieve there, the commitment to deal with the problem now. That’s the minimum. We have to do that equitably and we have to find a commitment that is quick. "
    Wadhams echoes the need for urgency.
    "The carbon that we’ve put into the atmosphere keeps having a warming effect for 100 years, so we have to cut back rapidly now, because it will take a long time to work its way through into a response by the atmosphere. We can’t switch off global warming just by being good in the future, we have to start being good now. "
     (22)Wadhams says there is no easy technological fix to climate change. He and other scientists say there are basically two options to replacing fossil fuels, generating energy with renewables, or embracing nuclear power.
Questions 19 to 22 are based on the recording you have just heard.
19. What did Pen Hadow and his team do in the Arctic Ocean?
20. What does the report say about the Arctic region?
21. What does Cambridge scientist Peter Wadhams say in his study?
22. How does Peter Wadhams view climate change?