全球变暖有望打通北极新航道

    全球气候变暖的乌云背后其实也透着一线光芒——地理学家们预测，到本世纪中叶，融化的海冰将在北极开辟新的商业航线。它将大大缩短船只在夏末的航行时间，还将削弱俄罗斯对横跨北极航运的控制。破冰船将破天荒地径直穿越北极，贯穿加拿大北极群岛的那条危机四伏、但令人垂涎欲滴的西北航道（NWP）终于有望成为一条可行的商业航线。

    美国加州大学洛杉矶分校（UCLA）的劳伦斯•C•史密斯和斯科特•R•斯蒂芬森在《美国国家科学院院刊》（Proceedings of the National Academy of Sciences）上发布了这项研究成果。这两位学者运用计算机模型，根据7项独立的气候模型，对本世纪中叶(2040-2059) 北大西洋和白令海峡之间的最优航运路线进行了预测。他们把研究限定在北极冰处于最低值的9月份。下面是他们的发现：

    • 北冰洋东部沿俄罗斯海岸的北海航线（NSR）——目前唯一可行的横跨北极航线——将变得更加通畅。北海线路将向更多普通的、无加固船体的开放水域船只（目前使用的绝大多数运输船都是这种）开放，起航自北大西洋的最佳航线将由俄罗斯海岸向北转移，进而脱离它的领土管辖范围。

    • 如今散落着约5万座高达300英尺巨型冰山的西北航道（NWP）将就此打开。相比于北海航线，往返北美的航程将减少30%。对于极地6级船只（Polar Class 6，波罗的海国家现在使用的轻量级破冰船）来说，它将成为夏末全天候通畅的最优航线，普通的开放水域船只在相当长的时间内也可以在这条航线上通行。“这的确令人称奇，因为西北航道的可航行度一直不如北海航线，冰封程度也远大于后者，”史密斯说。“这是一个非常难以驾驭的地方。”西北航道的开放或将迫使加拿大、美国和欧洲着手解决这条贸易路线究竟是位于加拿大水域，还是位于国际水域这个争执已久的问题。

    • 随着冰层变薄，北极将成为往返欧洲的破冰船的最优航线，可能会吸引一些北海航线的船只。到本世纪中叶，极地6级船只“几乎可以去任何一个它们想去的北极地区，”史密斯说。“届时，如果打算在大西洋和太平洋之间航行，最短的路线就是直接穿越北极。”

    尽管目前还无法搞清楚所有这一切具有的经济意义，但随着冰层退去，北极地区的航运已经开始升温。2010年夏，冰层变得足够薄的时候，有几艘运输船只首次通过了北海航线。去年夏天，46艘运送石油、天然气和硬矿石的船只曾经从俄罗斯、挪威和丹麦经由这条航线驶往中国，阿拉斯加费尔班克斯大学（University of Alaska Fairbanks）地理和北极政策教授劳森•布里格姆说。

    Call it a silver lining: Geographers are predicting that by mid-century, melting sea ice will open up new commercial shipping routes in the Arctic. That would shave off costly travel time in the late summer and reduce Russia's control over trans-Arctic shipping. For the first time, icebreakers will be able to make a straight shot over the North Pole, and the treacherous but coveted Northwest Passage through Canada's Arctic Archipelago will become a viable commercial route.

    UCLA's Laurence C. Smith and Scott R. Stephenson reported the findings on what they're calling "Supra-Polar" routes Monday in the journal Proceedings of the National Academy of Sciences. The pair used computer modeling to predict optimal navigation routes for mid-century (2040-2059) between the North Atlantic and the Bering Straight based on seven independent climate models. They restricted their study to September, when Arctic ice is at its minimum. What they found:

    • The Northern Sea Route (NSR) along Russia's coast in the eastern Arctic Ocean -- the only viable trans-Arctic shipping route today -- will continue to become more navigable. The NSR will open up to more ordinary open-water ships without reinforced hulls (the vast majority of shipping vessels in use today), and optimal routes from the North Atlantic will shift northward away from Russia's coast and out of its territorial jurisdiction.

    • The Northwest Passage (NWP), which today is littered with some 50,000 giant icebergs up to 300 feet tall, will open, reducing by 30% the distance for vessels traveling to and from North America compared with the NSR. It will be the optimal late-summer route for Polar Class 6 vessels (lightweight icebreakers used in the Baltic states today) 100% of the time and for ordinary open-water ships much of the time. "This is a surprise because the NWP has always been less navigable and more icy than the NSR," Smith says. "It's a very stubborn place." The opening up of the NWP may force Canada, the U.S. and Europe to settle a longstanding dispute over whether the trade route is in Canadian or international waters.

    • The North Pole will become the optimal route for ice-breaking ships traveling to and from Europe as the ice thins, which could pull traffic away from the NSR. Polar Class 6 vessels will "pretty much go wherever they please" in the Arctic by mid-century, Smith says. "At which point, if you're trying to get between the Atlantic and the Pacific, the shortest route is directly over the North Pole."

    Although it's too soon to know what all this means in economic terms, shipping is already ramping up in the Arctic as ice retreats. A handful of shipping vessels first navigated the NSR in 2010, when the summer ice thinned sufficiently there. Last summer, 46 ships carried oil, gas, and hard minerals from Russia, Norway, and Denmark to China, says Lawson Brigham, a professor of geography and Arctic policy at the University of Alaska Fairbanks.