The role of Arctic sea ice in climatic and ecological processes

在上个世纪，北冰洋海冰的面积和厚度都有所减少。这一趋势已经加速，预计未来几十年将出现夏季无冰的北冰洋。这代表着海冰融化的规模和速度发生了前所未有的变化，这在至少数千年里是独一无二的，也可能是人类文明史上独一无二的。据预测，海冰融化的影响将是广泛的，从当地陆地和海洋动植物分布的变化，到地球气候系统和海洋循环模式的变化：海洋动物和浮游生物分布的巨大变化，北极熊等关键物种栖息地的减少，或者是导致欧洲冬季更冷的北极-中纬度气候联系的增强。海冰是北极气候和生态的重要组成部分。它的白色表面就像一面镜子，反射进来的太阳光主要被反射回太空，而不是穿透海洋，困在我们的星球上。海冰的消失增加了进入地球的热量，进一步加速了全球变暖。海冰融化还会产生大量淡水，干扰全球海洋循环。因此，北极海冰的减少在北极进一步变暖(北极变暖比低纬度地区快得多)方面起到了很大作用。这促进了植物的生长，导致冻土带发生巨大变化。此外，许多动植物都是在海冰景观中进化出来的，而这些景观现在正在发生变化。这对北极熊、北极狐、北极鲸和海豹以及北极植物等动物的影响仍不清楚。由于北极生物学家和气候学家面临着对过去环境状况的稀缺和缺乏信息，对气候和生态的预期巨大影响迄今基本上没有量化。汇编北极的长期环境记录将允许对快速变化的环境的影响进行许多问题的测试。因此，整个北极海冰状况的长期(覆盖数千年)的急需记录是缺乏的。拟议项目的目的是制作它来回答对我们的社会有直接影响的关键问题，即：北极海冰的变化如何影响全球气候和高纬度生物群，我们未来可以从中学到什么？过去的海冰状况是通过对北极收集的材料的分析得出的，这些材料构成了过去海冰存在或不存在的证据(海冰替代物)。这种材料包括海洋底部过时沉积物中的分子和微生物，受海冰影响的冰芯和树轮，海滩上的冰留下的伤痕，以及鲸鱼骨骼或浮木等动植物遗骸。该项目提出了一项合作努力，将所有这些信息结合在一起，生成北极过去海冰动态的全景图。在所有海冰代理中，浮木是唯一一个不仅能告知过去的海冰状况，还能告知海冰从进入海洋到沉积在北极海滩上的漂流路线的唯一代理。由于北极如此寒冷，漂流木被完好地保存了一万多年。将使用新技术对现有材料进行分析，这些技术可以更精确地提供有关过去海冰范围和漂流路线的信息。将组织北极探险，为重点区域和时期收集新材料。这将有助于科学界回答有关海冰在北极气候和生物中的作用及其全球后果的问题。它还将把目前的变化放在一个更大的框架内，并提高我们对这种巨大的环境变化将对我们的星球产生的影响的理解，这是我认为这项研究提案最重要和最令人兴奋的地方。

In the last century Arctic sea ice has declined, both in extent and thickness. This trend has accelerated to the point where a summer ice-free Arctic Ocean is expected in the next decades. This represents an unprecedented change in scale and speed of sea ice-melt, unique for at least millennia, and also possibly in the history of human civilisation.The impacts of melting sea-ice are predicted to be wide-ranging, from alterations in the distribution of local terrestrial and marine fauna and flora, to changes to the earth's climate systems and ocean circulatory patterns: large shifts in the distribution of marine fauna and plankton, reductions in the habitat of key species such as the polar bear, or an enhanced Arctic-mid-latitudes climate connection responsible for colder winters in Europe are amongst these impacts. Sea ice is a key part of Arctic climate and ecology. Its white surface acts as a mirror for the incoming solar rays, which are largely reflected back into space, instead of penetrating the ocean and getting trapped in our planet. Sea ice loss increases the amount of heat entering our planet, further accelerating warming. Sea ice melt also creates great volumes of freshwater, interfering with the global oceanic circulation. Arctic sea ice loss thus plays a big role in further warming the Arctic (which warms much faster than lower latitudes). This enhances plant growth, causing large changes in the tundra. Plus, many plants and animals have evolved in landscapes with sea ice that are now changing. The consequences of this for animals such as the polar bear, the Arctic fox, Arctic whales and seals, and Arctic plants remain poorly understood.The anticipated large effects on climate and ecology are to date largely unquantified, due to the fact that Arctic biologists and climatologists are confronted with scarce and short information of past environmental conditions. The compilation of long environmental records for the Arctic would allow testing many questions about the effects of a rapidly changing environment. A much needed long (covering thousands of years) record of sea ice conditions for the whole Arctic is thus lacking.The aim of the proposed project is to produce it to answer key questions with direct implications for our society, namely: how changes in Arctic sea ice affect the global climate and the high latitude biota, and what can we learn from this for the future?Past sea ice conditions are inferred from the analysis of material collected in the Arctic that constitutes evidence of past sea ice presence or absence (sea ice proxies). This material consists of molecules and microscopic organisms in dated sediment at the bottom of the ocean, ice cores and tree rings affected by sea ice, scars made by ice on beaches, and animal and plant remains like whale bones or driftwood. This project proposes a collaborative effort to combine all this information and produce a full Arctic picture of past sea ice dynamics.Of all sea ice proxies, driftwood is the only one informing not only of past sea ice condition, but also of the drift routes sea ice took to deliver driftwood from the moment it entered the ocean to the moment it got deposited on Arctic beaches. Since the Arctic is so cold, driftwood is well preserved for more than 10,000 years. Existing material will be analysed using new techniques that can inform with improved precision about past sea ice extent and drift routes. Arctic expeditions will be organized to collect new material for key regions and periods.This will help the scientific community to answer questions about the role of sea ice in Arctic climate and biology and its global consequences. It will also put current changes in a larger framework and improve our understanding of the effects that this huge environmental change will have on our planet, which is what I find most important and exciting about this research proposal.