By Rajesh Mirchandani, BBC reporter, Los Angeles

媒體英語會帶大家一起學習BBC撰稿人在報道世界大事時常用到的單詞和短語。

Background: 美國政府指定阿拉斯加沿海的大片區域作為北極熊的危急棲息地。這片區域包括石油公司準備勘探的油區。環保人士希望這個舉動能夠挽救北極熊這個瀕危物種的生存。

Right now in an icy den in the Arctic, a polar bear is giving birth to cubs, or is about to. But the very survival of this fearsome, majestic species concerns many humans.

Polar bears live and hunt on sea ice but the frozen Arctic Ocean is melting at an increasing rate, a result, scientists say, of global warming caused by greenhouse gases.

Now the US government has designated nearly half a million square kilometres in Alaska as critical habitats for the polar bear. It covers an area of roughlytwice the size of the United Kingdom, and it means any proposed economic activity there must be weighed against its impact on the bears’ habitat. It includes some of the Chukchi and Beaufort seas, exactly where the oil company Shell wants to drill.

The designation itself doesn't ban oil exploration, but it adds extra hurdles that opponents say will harm the economy.

Environmentalists welcome the move, saying now, they can write a recovery plan for polar bears, not an obituary.