Tracking the world's biggest iceberg as it drifts towards oblivion
追踪世界上最大的冰山如何逐渐消亡
The world's biggest iceberg - more than twice the size of Greater London - is on the move. After a few weeks loitering on the fringes of Antarctica, it’s begun to drift at pace once more.
世界上最大的冰山——面积是大伦敦地区的两倍多——正在移动。在南极洲边缘徘徊了几周后，它再次开始快速漂移。
A23a, as it’s known, broke away from the Antarctic coastline way back in 1986, but it's only recently begun a big migration. For more than 30 years, it was stuck rigidly in the bottom-muds of the Weddell Sea like a static "ice island". A 350m-deep keel had anchored it in place. It took gradual melting until 2020 to allow the berg to re-float and start moving again, slowly at first, before currents and winds then swept it north towards warmer air and waters.
众所周知，A23a 早在 1986 年就脱离了南极海岸线，但直到最近才开始大规模迁徙。 30多年来，它像一座静止的“冰岛”一样牢牢地卡在威德尔海的海底泥浆中。 350m 深的龙骨将其固定到位。直到 2020 年，冰山才逐渐融化，才重新漂浮并开始再次移动，一开始速度很慢，然后被洋流和风吹向北方，向温暖的空气和水域移动。
A23a is now following a path that exports so much of Antarctica's floating ice - what scientists refer to as "iceberg alley". It’s a path to destruction. It's going to fragment and melt to nothing in just a matter of months. Today, the behemoth is drifting along the 60th Parallel, close to the South Orkney Islands, about 700km (430 miles) northeast of the tip of the Antarctic Peninsula.
A23a 现在正沿着一条出口大量南极洲浮冰的路径——科学家称之为“冰山巷”。这是一条通往毁灭的道路。它会在短短几个月内碎裂并融化成碎片。如今，这头庞然大物正沿着北纬 60 度漂流，靠近南奥克尼群岛，距南极半岛尖端东北约 700 公里（430 英里）处。
The process of decay is already evident in satellite imagery and close-up photos taken from visiting ships. Every day, large chunks are falling off into the sea. The interplay of winds, ocean fronts and eddies will determine A23a's precise course over the coming weeks but many of these giant, flat-topped - or tabular - bergs end up passing by South Georgia, roughly 650km (400 miles) north-east of its present position. The British Overseas Territory, it seems, is where a lot of icebergs go to die.
卫星图像和来访船只拍摄的特写照片中已经很明显地看到了腐烂的过程。每天都有大块的石块落入海中。风、海滨和涡流的相互作用将决定 A23a 在未来几周内的精确路线，但许多这些巨大的平顶或板状冰山最终会经过南乔治亚岛，位于其现在位置东北约 650 公里（400 英里）处。英国海外领土似乎是许多冰山死亡的地方。
The size of A23a can be hard to fully comprehend. When scientists working on the European Space Agency's CryoSat-2 mission used a radar altimeter on the spacecraft to estimate the iceberg’s girth, they found it to have an average thickness of just over 280m (920ft). For comparison, the Shard in London, the tallest skyscraper in western Europe, is 310m (1,020ft) tall.
A23a 的大小可能很难完全理解。当参与欧洲航天局 CryoSat-2 任务的科学家使用航天器上的雷达高度计来估计冰山的周长时，他们发现冰山的平均厚度刚刚超过 280 m（920 英尺）。作为参照，西欧最高的摩天大楼-伦敦碎片大厦高 310m（1,020 英尺）。
Even sailing right up to its 30m-high cliff face wouldn't really let you grasp its scale - no more than standing in front of the facade of Buckingham Palace would let you gauge the size of London. Although its size is reducing with every passing day, the huge iceberg is still about 3,800 sq km (1,500 sq miles) - larger than 29 countries, including Luxembourg, Bahrain and Singapore.
即使直接航行到 30m 高的悬崖表面也无法真正让您了解它的规模 - 就像站在白金汉宫正面前无法让您衡量伦敦的大小一样。尽管其尺寸日渐缩小，但这座巨大冰山的面积仍然约为 3,800 平方公里（1,500 平方英里）——比卢森堡、巴林和新加坡等 29 个国家还要大。
Energetic waves are cutting into the berg's walls, sculpting enormous caves and arches, which are collapsing to expose wide terraces of submerged ice. Buoyancy is then forcing these terraces up to the surface, ripping away the edges of the berg in the process. But warmer air also is gradually taking its toll. Meltwater will be collecting at the berg's surface, trickling down into cracks and forcing the fissures deeper and deeper until they break all the way to the bottom.
高能量的波浪正在切入冰山的墙壁，雕刻出巨大的洞穴和拱门，这些洞穴和拱门正在倒塌，露出宽阔的水下冰层。然后，浮力迫使这些梯田上升到表面，在此过程中撕掉了冰山的边缘。但温暖的空气也正在逐渐产生影响。融水将在冰山表面聚集，滴入裂缝中，迫使裂缝越来越深，直到它们一直破裂到底部。
A23a will have its legacy. Like all big bergs, its progressive melt will be dispersing the mineral dust that was caught up in its ice when still part of a glacier. In the open ocean, this dust is a source of nutrients for the organisms that form the base of ocean food chains. From plankton up to great whales - all will benefit from the big berg's extinction.
A23a 将带来它的遗产。像所有的大冰山一样，它的逐渐融化将驱散当它仍然是冰川的一部分时被冰所捕获的矿物尘埃。在公海中，这些灰尘是构成海洋食物链基础的生物体的营养来源。从浮游生物到巨型鲸鱼——所有都将从大冰山的灭绝中受益。
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