南极冬季海冰范围达到有记录以来第三低水平，比长期平均值少了100万平方公里——约合40万平方英里，科学家已确认这一数据。
Antarctica’s winter sea ice has peaked at its third-lowest level on record, falling a million square kilometres – or almost 400,000 square miles – short of the long-term average, scientists have confirmed.
这一峰值的确认意味着，南极海冰——地球气候系统的关键组成部分，对海洋生物至关重要——有记录以来最低的四个年份全部出现在过去四年中。
Confirmation of the peak meant the four lowest years on record for the continent’s sea ice – a vital component of the planet’s climate and critical for marine life – had all occurred in the past four years.
卫星自1979年起开始监测南极海冰，今年数据显示，海冰于9月14日达到峰值，面积为1759万平方公里，比平均最大值少了约100万平方公里，相当于大约两个西班牙的面积。
Satellites have been watching the continent’s sea ice since 1979, and this year data showed the sea ice peaked on 14 September at 17.59m square kilometres, about a million square kilometres short of the average maximum or an area roughly twice the size of Spain.
美国科罗拉多大学国家冰雪数据中心高级科学家沃尔特·梅耶博士表示，该中心此前未宣布达到最大值，是因为在海冰周期的这个阶段存在“巨大的潜在变率”。
Dr Walt Meier, a senior scientist at the National Snow and Ice Data Center at the University of Colorado, said the centre had held off in declaring the maximum because there was a “lot of potential variability” at this stage in the continent’s sea ice cycle.
但自9月14日起海冰水平一直在下降，他现在认为“最大值已达到”。南极海冰经历巨大的年度波动，夏季融化至200万平方公里以下（近年2月均如此），冬季增长至9月超过1700万平方公里。
But the levels of sea ice had been falling since 14 September and he now thought “the maximum has been reached.”Antarctica’s sea ice goes through an enormous annual swing, melting through summer to below 2m sq km in recent Februaries and then growing through winter reaching above 17m sq km in September.
但近年来冬季和夏季海冰最低纪录屡被打破，引发担忧：全球变暖可能正在推动这一损失。
But recent years have seen records broken for low sea ice in both winter and summer, raising concerns that global heating could be driving the losses.
墨尔本莫纳什大学南大洋专家阿里安·普里奇博士表示：“过去四个冬季的海冰最大值均为有记录以来最低——这是系统发生变化的非常明确的信号。”
“The past four winters have had the lowest sea ice maximum on record – that’s a very clear indication of a system that has changed,” said Dr Ariaan Purich, a Southern Ocean expert at Monash University in Melbourne.
“这不再是一次性事件。海冰不再覆盖过去同样范围的海洋。我们看到一个接一个的低海冰冬季，这表明海冰行为发生了变化，因为我们让气候变暖了。”
“This is not a one-off event any more. The sea ice is no longer covering the same extent of ocean that it used to. We are seeing low winter after low winter and that suggests the sea ice is behaving differently because we have warmed our climate.
“这不是未来的问题，而是当下的问题。”6月，南极半岛经历了一场热浪，气温比正常水平高出20摄氏度，与此同时，科学家们指出了一片法国大小的开阔海域，那里本应被冰覆盖。
“This is not a future problem. It’s a now problem.”In June, the Antarctic peninsular saw a heatwave with temperatures 20C above normal while scientists pointed to a France-sized area of open ocean where ice should have been.
8月初，本应是海冰稳步扩张的时期，位于太平洋以南的阿蒙森海却有大片区域失去了冰层。
In early August when sea ice should be steadily expanding, a large area of the Amundsen Sea to the south of the Pacific lost ice.
Purich表示，与热带太平洋厄尔尼诺气候模式相关的风向变化，很可能在该地区海冰减少中发挥了作用。
Purich said changes in winds associated with the El Niño climate pattern in the tropical Pacific had likely played a role in reducing the sea ice in that region.
澳大利亚气象局监测南极状况的Phil Reid博士表示，厄尔尼诺现象往往会改变南极周围风暴系统的移动路径，导致一些风暴系统滞留在同一地点，搅动下方的海冰。
Dr Phil Reid, who monitors Antarctic conditions at Australia’s Bureau of Meteorology, said El Niño tended to change the movement of storm systems around Antarctica leading some to be held in the same place, churning up the sea ice below.
但他表示，即使没有厄尔尼诺现象，“我认为我们仍将处于类似的境地……这有点令人不安，”他说。
But he said even without an El Niño, “I think we would still be in a similar position … and that is a bit disconcerting,” he said.
“大气会有一些变化，但最终热力学占主导。如果水温过高，海冰就会减少。”Purich表示，随着南极现已走出“极夜”，海冰白天会反射太阳能量。但海冰减少意味着南大洋能吸收更多热量。
“The atmosphere will play around a bit, but in the end thermodynamics wins. If the water is too warm, you won’t have as much sea ice.”Purich said as Antarctica now emerged from its “polar night”, sea ice reflects the sun’s energy during the day. But less sea ice meant the Southern Ocean could take up more heat.
海冰消失不会直接影响海平面，因为它本身就在漂浮，但它会让冰架暴露在剧烈的海洋条件下并使其变弱。
Loss of sea ice does not directly affect sea levels as it was already floating, but it can expose ice shelves to buffeting ocean extremes and weaken them.
冰架减缓冰川和该大陆巨大冰盖的推进，如果冰盖流入海洋，有可能将全球海平面推高数米。除了为藻类和磷虾（大陆食物网的关键要素）提供栖息地外，不稳定的海冰还引发了对其他物种的担忧，包括利用冰层繁殖和抚育幼崽的帝企鹅。
Ice shelves slow down the advance of glaciers and the continent’s vast ice sheet that has the potential to push up global sea levels by many metres if it reaches the ocean As well as providing habitats for algae and krill – critical elements of the continent’s food web – unstable sea ice has raised concerns for other species, including emperor penguins, that use the ice to breed and raise young.
塔斯马尼亚大学南极海冰专家Will Hobbs博士表示，自本月初达到峰值以来，南极海冰一直在“比往常更快地”减少。
Dr Will Hobbs, Antarctic sea ice expert at the University of Tasmania, said since reaching its peak earlier this month, Antarctic sea ice had been dropping “faster than usual”.
“我们可能面临另一个低冰量的夏天，那才是真正令人担忧的时候，”他指着对冰架影响的担忧说道。
“We could be looking at another low summer and that’s when things get really worrying,” he said, pointing to concerns about impacts on ice shelves.
“全球气候系统对这种海冰消失有多敏感？我们仍在努力量化这一点。但系统变化的速度比我们理解它的速度还要快。”
“How sensitive is the global climate system to this loss of sea ice? We are still working to put numbers on that. But the system is changing faster than we are understanding it.”