If you want to see climate change, head north and keep going until you run out of globe. That is easier said than done. The Arctic (北极) is home to few people and covered in ice much of the year. But those who make their way to the icy seas of the Arctic Ocean will see a part of the planet that is warming and changing faster than anywhere else.
In September, scientists announced at the National Snow and Ice Data (数据) Center that Arctic summer sea ice had fallen to its second lowest level since 1979, and probably long before that. The Arctic has lost an area of ice greater than the area of all U.S. states east of the Mississippi River. And what ice remains appears to be getting thinner and weaker.
Nick Toberg and Till Wagner are polar ice scientists who are doing sea ice fieldwork. “There is plenty of data to suggest that the ice is becoming thinner as well as smaller in area,” they say.
The changes happening in the Arctic are a warning for the entire world .  As polar expert Walt
Meier puts it, “What happens in the Arctic doesn’t stay in the Arctic.”
Some scientists worry that Arctic sea ice may be going from a downward spiral (螺旋线) to a “death spiral”, one from which there is no escape. As more ice melts (融化), more dark open water appears. The darkness absorbs (吸收) more heat, which speeds up the pace of melting.
Until recently, many scientists thought it might take until the end of the century for the North Pole to become completely ice free during the summer. Now some believe it could happen by 2030 or even earlier. “The melting is happening faster in the real world than it has in the models,” says Nick Toberg.
The purpose of the first paragraph is to tell readers __________.

A．it’s difficult to arrive at the Arctic

B．it is too cold for people to live in the Arctic

C．what caused the climate change in the Arctic

D．we can see the most obvious climate change in the Arctic

From the second paragraph we can learn Arctic summer sea ice __________.

A．is still decreasing

B．began reducing in 1979

C．fell to its lowest level in September

D．is equal to the Mississippi River

What does the underlined sentence in Paragraph 3 mean?

A．The changes don’t affect the Arctic at all.

B．The changes will only happen in the Arctic.

C．The changes happening in the Arctic will stop.

D．The changes will also affect other parts of the world.

Nick Toberg may agree that __________.

A．the ice in the North Pole will stop melting

B．the ice in the North Pole is melting faster than expected

C．the ice in the North Pole will melt before 2030 or even earlier

D．the ice in the North Pole will not disappear until the end of the century