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SAN FRANCISCO, CALIFORNIA—A continually warming Arctic is having profound impacts across the top of the planet and beyond, according to a government report released here today at a meeting of the American Geophysical Union. The effects include weather disruptions, disappearing snow, and lands greening as temperatures rise. But some of the biggest changes are happening in warming Arctic seas, with the future of northern fisheries hanging in the balance. 加州旧金山消息—今天，美国地球物理学会在这里举行了一次会议，会上发布的一项政府报告中说：不断变暖的气候正在对地球的北极地区及以南地区产生深远而广泛的影响，这种影响包括随着气温的上升而出现的气候混乱、冰雪消融和土地绿化。但是，一些最大的变化发生在北极的海洋中，这对于北部地区未来的渔业而言是福祸难料的。 The latest version of the Arctic Report Card, first released in 2006, showed that warming trends remain largely consistent in the Arctic, which is warming, on average, twice as fast as the rest of Earth. Snow cover on land was below the average of the previous 3 decades; for the 10th straight year, June featured record lows over land in the North American and Eurasian sectors of the Arctic. Loss of sea ice and the melting of the Greenland Ice Sheet slowed, though summer temperatures on the ice sheet set records. 最初，北极年度报告是于2006年发布的。这份最新的北极年度报告显示，北极地区的变暖趋势在很大程度上是一直持续的，平均变暖速度为地球其他地区的两倍。覆盖在土地上的积雪少于前30年的平均水平；北极圈内的北美地区和欧亚地区在六月份的积雪覆盖面积连续第10年达到最低纪录。海冰消失的速度和格陵兰冰盖融化的速度减慢了，但冰盖上的夏季温度仍然创了最高纪录。 This year offered new insight into the future of the Arctic marine ecosystem, one of the biggest question marks as the region warms. The first task is to get a handle on all the factors that explain why the Arctic, mostly ocean, is warming up so fast. A couple of factors are warm air coming in from the tropics and replacement of white sea ice—which reflects heat back into the atmosphere—with dark, absorbent water. 有关北极的海洋生态系统，今年的北极年度报告为研究人员提供了新的认识——最大的问题就是海洋区域的变暖。首要任务就是要掌握所有的因素，搞清到底是什么使大部分区域为海洋的北极地区发生了如此迅速的变化。其中有两个因素：一个是温暖的气流来自热带地区；另一个是具有吸热性能的深色水域替代了白色的海冰，而白色的海冰本来是可以将热量反射回大气中的。 A new clue may be in the water itself, says Kathy Crane, an oceanographer with the National Oceanic and Atmospheric Administration (NOAA) in Silver Spring, Maryland, which published the report. Ships studying currents have recently identified new flows of warm water entering the Arctic through the Bering Strait on the Pacific side and the Norwegian Sea on the Atlantic side. “We not only have the solar radiation, but we have these currents to bring water in laterally,” she says. 马里兰州银泉市美国国家海洋和大气管理局（NOAA）发布了这则年度报告，该局的海洋学家凯西·克兰称，一条新线索存在于海水本身。最近，研究洋流的轮船发现两股新的温暖水流进入北冰洋，太平洋那边的一股通过白令海峡进入北冰洋，而另大西洋那边的一股通过挪威海进入进入北冰洋。她说：“这里不但有太阳的辐射，而且还有这些洋流将温暖的水从侧面带进来。” All of this warming could have a dramatic impact on the region’s fish. The Bering Sea, between Alaska and Russia, and the Chukchi and Laptev seas, off eastern Siberia, saw summer temperatures 4°C higher than the average of the previous 3 decades. This, along with acidifying waters, could spell doom for many species, for example crustaceans whose shells may dissolve. And warming temperatures can have an uncertain impact on Arctic fish, says Jim Ianelli, a fisheries biologist with NOAA in Seattle, Washington. Alaska pollock, an important fish commercially, was thought to benefit, on average, from warm conditions, which may stimulate the ecosystem as a whole. But new findings suggest that cold temperatures are important, too: Cool waters in the fall and winter encourage the growth of nutritious microorganisms that young fish need to grow. With waters projected to continue to warm, NOAA now projects a likely decline in the amount of Alaska pollock by 2050. 所有这些变暖趋势都有可能对该地区的鱼类产生重大影响。白令海位于美国阿拉斯加州、俄罗斯、楚科奇海和东西伯利亚附近的拉普捷夫海之间，这里在夏季的温度比前30年的平均温度高出了4°C。华盛顿州西雅图市NOAA的渔业生物学家吉姆·伊安涅利称：逐渐升高的温度对北极鱼类的影响是不确定的。阿拉斯加鳕鱼是一种重要的商业鱼类资源，有人认为从整体来讲这种鱼会得益于温暖的环境条件，因为温暖环境可以使整个生态系统活跃起来。然而，新发现表明寒冷的温度也很重要：秋冬季的冷水能够促进富有营养的微生物生长，而这些微生物正是幼鱼生长所需要的食物。随着这些水域继续变暖，目前NOAA预计到2050年阿拉斯加鳕鱼的数量会有所减少。 2014 showed the promise of a new, productive Arctic Ocean as well: In the Kara and Laptev seas off Siberia, for example, satellites measured higher than normal levels of chlorophyll, which strongly suggests increased growth of crucial marine plants like algae. 2014的年度报告显示，北冰洋也有希望出现多产的新物种。例如，在西伯利亚附近的喀拉海和拉普捷夫海海域中，卫星观测发现叶绿素高于正常水平，这有力地说明像海藻之类的关键海洋植物有了显著的增多。 The Barents Sea was colder than usual in 2014, but the trend since 1981 is warming. That may be why scientists have seen cod and other fish from the northern Atlantic migrating north from Barents Sea fisheries into the Arctic Ocean. “It’s very much a concern in Norway and among the Russians, who worry the fish may be leaving fisheries,” says Crane, who helped lead the report. Crane, with NOAA, says that satellite measurements are adequately monitoring parameters like sea ice and vegetation on tundra from space. “But they don’t tell us what’s happening inside the Arctic Ocean. For that we need continuous and improved measurements.” 2014年，巴伦支海比往常温度更低，但是这里自从1981年以来的趋势也是正在变暖。这或许能够解释科学家们为何观察到了鳕鱼和其他鱼类从北大西洋地区向北迁移，从巴伦支海渔场迁移到北冰洋中。作为NOAA北极年度报告主要撰写人的克兰说：“在挪威和俄罗斯，这是人们非常关心的问题，他们担心这些鱼会离开那里的渔场。”克兰称：“来自太空的卫星测量正在充分地监督海冰和苔原上的植被等情况。但是，卫星数据不能向我们展示北冰洋里发生了什么。为此，我们需要不断地改进测量手段。” For the first time, NOAA included details about how the warming Arctic may be linked to weather further south—even causing cold weather in North America and Europe. January and March of this year included “periods of strong connection” between the pole and mid latitude, according to the report. The “polar vortex,” which separates arctic and tropical air, weakened, the report said, allowing warm air to flow north in January, when Alaska saw temperatures 10°C warmer than usual. Meanwhile, frigid arctic air dipped low into eastern North America and Russia, and winter months were 5°C colder than average. Emerging science about these linkages has spurred NOAA to focus its Arctic research program on the problem, Crane says. 不断变暖的北极地区与再往南一些地区的天气情况是相互关联的，甚至引起了北美和欧洲的寒冷天气，NOAA首次将其中的细节都写进了报告。根据这则报告，今年1月份与3月份就出现了北极和中纬度地区天气“密切相关的时期”。报告中说：“极地涡旋”作用是将北极和热带的气流隔开，可是极地涡旋的减弱使温暖空气在1月份流向北方，当时阿拉斯加的温度比往年同期升高了10°C。同时，寒冷的北极气流流入北美东部和俄罗斯，使这些地区数月之久的冬季比往年平均气温降低了5°C。克兰说，新兴的科学促使NOAA将北极研究计划重点放在这些关联问题上。 |
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