The Big Unknown in Sea-Level Rise
by Carolyn Gramling 胡德良 译
In 2007, the Intergovernmental Panel on Climate Change (IPCC) made a big splash, stating that global sea levels may rise between 18 centimeters and 59 centimeters by 2100. But those numbers were fraught with uncertainties—the most looming of which was the potential contribution to sea-level rise from melting of the giant ice sheets now blanketing Greenland and Antarctica. So the European Union's science funding program, Framework 7, created a research consortium, dubbed ice2sea, to study ice loss processes on continents (such as what hastens calving, pictured above in Greenland) as a way to estimate how much continental ice will add to future sea-level rise. Today, scant months before IPCC prepares to release its fifth assessment in September, ice2sea scientists released a preview of their findings. The upshot: Assuming a midrange emissions scenario, ice sheets and continental glaciers alone will contribute between 3.5 centimeters and 36.8 centimeters of sea-level rise by 2100. In the worst-case scenario (the likelihood of this happening is 1 in 20), continental ice melting could produce 84 centimeters of sea-level rise—not counting potential contributions from other sources, particularly thermal expansion (water expands as it warms). Even 90 centimeters of sea-level rise would hit coastal areas hard, producing routine flooding in low-lying cities such as Miami and New York. But the real inundation might come after 2100. Antarctica's rapidly retreating Pine Island Glacier is a sort of poster child for ice loss in Antarctica, and its retreat seems likely to continue to the end of the century even as the rest of the Antarctic ice sheet remains fairly stable. Moving into the next century, neighboring Thwaites Glacier could become destabilized, potentially adding tens of centimeters to sea-level rise—and that will really make a splash. | 2007年,政府间气候变化专门委员会(IPCC)声明:到2010年,全球海平面可能会升高18厘米至59厘米。该声明引起了巨大的轰动。但是,这些数字充满了不确定因素,其中最大的不确定因素就是:搞不清目前覆盖格陵兰岛和南极洲的大型冰原所形成的融水对海平面的上升会造成多大的潜在影响。因此,欧盟的科学资助项目——第七框架计划(Framework 7),创建了一项被称为“由冰到海(ice2sea)”联合研究项目,该项目研究大陆地冰的融化过程,以便估计在未来陆地冰会造成多大幅度的海平面上升。该研究包括图中所示的格陵兰岛:到底是什么加速了那里的冰崩坍呢?现在,离IPCC准备在九月份发布第五次评估只有短短几个月了,“由冰到海”项目的科学家们事先发布了他们的发现。结果是:假如陆地冰为中等程度的融化,那么到2100年仅仅冰原和陆地冰川就会造成海平面上升3.5厘米至36.8厘米。最坏的情况为:不考虑其他来源所造成的潜在影响,尤其是热膨胀所造成的影响(水遇热就会膨胀),仅仅陆地冰的融化可能会造成海平面上升84厘米;这种情况发生的概率为二十分之一。90厘米的海平面上升幅度会严重影响到海滨地区,经常会使迈阿密和纽约等低洼城市发生海水泛滥。但是,真正的淹没可能会在2100年之后到来。南极洲松岛冰川(Pine Island Glacier)的快速萎缩就是南极洲冰融化的典型征兆,尽管南极冰原的其他区域仍然相当稳定,但是该冰川的萎缩可能会持续到本世纪末。进入下个世纪时,附近的特怀特冰川(Thwaites Glacier)可能会失去稳定性,因而可能会使海平面升高几十厘米,到那时才会真正引起轰动呢! |
译自:美国《科学》杂志网站(14 May 2013, 5:35 PM)
原著:Carolyn Gramling
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