Ocean2ice

想象一下，海洋就像一个大的杜松子酒和滋补品。当你往饮料里加冰时，杯子里的水就会上升。当冰块融化时，杯子里的水平面不会改变，因为冰是浮动的。当目前南极洲陆地上的冰进入海洋时，无论是作为冰山还是作为融水，世界各地的海平面都会上升。过去人们认为，与降雪量相同的水回到南极，以补偿冰山和融水，因此整个系统处于平衡状态。但南极（和格陵兰）的一些冰川似乎正在以比它们被取代的速度更快的速度融化。所以冰的总量正在变小，因为更多的水在海洋中，增加了海平面上升。这是令人担忧的，因为我们真的不知道为什么会发生这种情况，如果我们不能理解为什么，就很难预测未来海平面是否会以越来越快的速度继续上升，或者它是否会放缓或回到平衡状态。政府计划在未来几十年在低洼地区进行海平面防御，需要对可能的水平有更确定的预测。这意味着他们用来预测未来气候的大型计算机模型需要比现在更好、更复杂的物理学。那么，科学家们能做些什么来找出冰融化的原因呢？当冰川最终到达大海时，它们漂浮在海水上，就像冰架一样。一种说法是，海洋提供了比过去更多的热量来融化冰层。尽管南极的海洋并不那么温暖，但它比冰点高几度，如果它在冰架下冲刷，它可以释放出大量的热量。我们在这个项目中计划做的是去一个融化最快的冰川，南极洲阿蒙森海的松岛冰川。这是我们星球上最偏远的地方之一-想象一下去太平洋，然后向南走，直到你遇到南极洲。我们将在冰架附近的水中放置一些仪器，看看温暖的海水是如何以及为什么接近冰的。是风把水吹到那里的吗？是波浪在绕着南极大陆吗？这些水是不是在几千年前被冰川凿出的海底槽中被引导上去的？我们计划在南极使用一些新的设备，比如把微型传感器粘在海象的皮毛上。在我们回家很久之后，海豹将在这个地区过冬。它们的传感器将发回有关海豹栖息地的信息，例如温度和盐度。这对我们很有用，因为我们不能在冬季以任何其他方式进行观测，因为该地区被海冰覆盖。这对海豹有好处，因为这将帮助我们的生物学家同事更好地了解象海豹对气候变化的脆弱性。我们还将在水中放置一个机械版的海豹，称为海上滑翔机。它会在水中上下移动，一边移动一边进行测量，就像海豹传感器一样，当它在水面上时，它会用移动的电话进行通信。当我们和船一起在那里的时候，我们会做很多测量，比如水的温度和盐度，它的速度，以及它的混合程度。把所有这些数据集放在一起看，应该能让我们更好地理解热量是如何到达冰川的，其中一个重要的工具就是各种计算机模型。这些模型将包括所有唱歌，所有跳舞的气候模型，试图包括冰，海洋和大气的相互作用，以测试我们对物理学的理解。我们计划做的工作的最终结果应该是更好的气候模型来预测未来的海平面。

Imagine that the ocean is like a large gin and tonic. When you add ice to the drink, the level in the glass goes up. When the lump of ice melts, the level in the glass doesn't change, because the ice is floating. When ice that is currently resting on land in Antarctica goes into the sea, either as an iceberg or as meltwater, the sea level all over the world goes up. It used to be thought that the same amount of water went back to the Antarctic as snowfall, to compensate for the icebergs and meltwater, so the whole system was in balance. But some glaciers in the Antarctic (and Greenland) seem to be melting at a faster rate than they are being replaced. So the total amount of ice is getting smaller, because more of that water is in the ocean, adding to sea level rise. This is worrying, because we don't really know why this is happening, and if we can't understand why, it's difficult to predict whether future sea level will carry on increasing at a faster and faster rate, or whether it will slow down or go back to equilibrium. Governments planning sea level defences in low-lying areas for the next decades need to have a more certain prediction of likely levels. That means that the big computer models that they use to forecast future climates need to have even better and more complex physics than they do already.So, what can scientists do to find out why the ice is melting? When the glaciers finally reach the sea, they float on the seawater, as an ice shelf. One suggestion is that the ocean is providing more heat to melt the ice than it used to do. Even though the ocean isn't that warm in the Antarctic, it is a few degrees above freezing, and if it washes underneath the ice shelves it can give up a lot of heat. What we plan to do in this project is to go to one of the fastest melting glaciers, the Pine Island Glacier in the Amundsen Sea, Antarctica. This is one of the most remote parts of our planet - imagine going to the Pacific Ocean and then heading south until you meet Antarctica. We will put some instruments in the water near the ice shelf, to see how and why the warm ocean water gets close to the ice. Is it the wind that forces the water there? Is it waves going round the Antarctic continent? Does the water get channelled up troughs in the sea floor gouged by glaciers thousands of years ago?We plan to use some novel equipment in the Antarctic, such as gluing tiny sensors onto elephant seals' fur. The seals will remain in the area over winter, long after we've gone back home. Their sensors will send back information about the seals' habitat - for example the temperature and the saltiness. This is useful for us because we can't get observations in the wintertime any other way because the area is covered in sea ice. And it's good for the seals because it will help our biologist colleagues to better understand how vulnerable the elephant seals might be to climate change. We'll also put in the water a mechanical version of a seal, called a Seaglider. This goes up and down in the water making measurements as it goes, and much like the seal sensors, it will communicate when it's at the surface using mobile phone. While we're there with the ship, we'll make lots of measurements of the temperature and saltiness of the water, how fast it's going, and how mixed up it is. Looking at all these data sets together should give us a better understanding of how the heat is getting to the glacier.One of the important tools will be a variety of computer models. These will range from all-singing, all-dancing climate models, that try to include ice, ocean and atmosphere all interacting, to much simpler models that test our understanding of the physics at play. The final result of the work we plan to do should be better climate models to predict future sea levels.