气候变化：北极驯鹿数量跌半

在过去的二十年间，北极地区的北美驯鹿（或野生驯鹿）的总数已骤减多半。一份关于北极地区气候变化影响的新报告显示，这类驯鹿的总数从近五百万只下降到约二百一十万只。这项报告在美国地球物理联盟（American Geophysical Union）会议上发表。

A warmer Arctic and greener tundra might sound like good news for grazing animals. But the changes in the far north are actually making life much more challenging for wild reindeer.

更暖的北极和更郁郁葱葱的苔原带对于草食动物来说似乎是个好消息。但在遥远的北方，这些变化实际上使野生驯鹿的生存变得更加艰难。

The animals rely on low-growing lichens, which are being swamped by taller plants. And more rain, rather than snow, when it falls onto freezing ground, forms a hard layer of ice that the animals simply can't push their noses through to feed.

这些动物靠矮生地衣为生，但地衣正被长得更高的植物没过。同时，更多的降雨而非降雪使得雨滴落在冻土上时形成坚固的冰层，这样一来驯鹿完全没办法把鼻子伸进去进食。

It's also said that a good summer day for a human in the Arctic, still and warm, is a horrible day for the reindeer because they're mobbed by the increasing number of insects. During warmer summers, the animals have to use so much energy to keep the flies away that they can't sustain themselves. The same report revealed that sea ice continues to shrink, and that changes are fuelling extreme weather patterns further south.

也有人说，北极地区的一个宁静而温暖的夏日对于人类来说虽然是很舒适的，但对驯鹿来说却很可怕，因为它们被日益增多的虫子围攻。在更温暖的夏日里，这些动物为驱赶蝇虫，不得不消耗很多能量，以至于无法维持自身的生存需要。报告还显示，海冰仍持续缩小，而且这些变化正在加剧更南边地区的极端天气模式。