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The response of the Arctic regions to changing climate

北极地区对气候变化的反应

基本信息

批准号：
NE/H000437/1
负责人：
Richard Essery
金额：
$ 44.78万
依托单位：
University of Edinburgh
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH000437%2F1
关键词：
response Arctic regions changing climate

项目摘要

The anthropogenic burning of fossil fuels is affecting the climate system via raised atmospheric CO2 concentrations. But are there aspects of the natural Earth system that, when forced by imposed climate change, have themselves a major impact on the carbon cycle? Such climate-carbon (C) cycle feedbacks might be positive - that is, they may cause a reduction in the current capability of natural systems to mitigate anthropogenic CO2 emissions, or may even force natural systems to become direct sources of CO2. Such positive feedbacks are a major cause for concern, and their initiation could be regarded as a climate 'tipping point'. It has been hypothesised that the Arctic land surface could be one such 'tipping point', whereby global warming is sufficient to induce soil C losses greater than any extra draw-down of C through enhanced tundra (shrub) and boreal forest growth in a warmer, CO2-enriched environment. In addition, a warmer climate will impact on the on the energy and water cycles, with less snow cover in Northern Latitudes reducing surface reflectivity and so inducing additional warming. In reality the energy, water and C cycles are all strongly linked and need to be modelled interactively to provide robust estimates of the future. Global Circulation Models (GCMs) are designed to emulate the climate system and the global carbon cycle, and in the process, provide pointers to potential 'tipping points' in the climate system. But their predictions for the Arctic region will only be as good as the hydrology, ecology and energy interactions depicted in the land surface model for that region. This project therefore has two aims - to provide much more physical realism in land surface models, and then to see how this enhancement impacts on modelled future climate. Does the Arctic region eventually enhance human-induced climate change by increasing future levels of atmospheric carbon dioxide? Modelling the land surface for the Arctic region is complicated. To get this correct, we will need to capture how the vegetation may grow and expand in a warmer environment, and how this might change soil C stocks. We also need to model how the snow interacts with vegetation - snow cover will change with climate, and will influence the energy inputs, the water cycle, the frozen ground and the vegetation distribution. For example, deeper snow will occur in areas of tall vegetation and thus vegetation structure influences not only the timing of snow melt but also the thermal regime as deeper snow actually insulates the soils. There is thus a knock-on effect on soil respiration and vegetation growth. This project will model all of these features, dynamically, such that the impact of future temperature and snowfall patterns on the Arctic ecosystems can be assessed. Extensive use will be made of existing observational datasets developed by the PIs and others over the last decade and, in particular the International Polar Year. This new knowledge of the Arctic land surface will be introduced within a pan-Arctic gridded modelling system. The local and regional behaviours will be integrated to determine net land-atmosphere CO2 fluxes. However, major future changes in land surface behaviour might have strong feedbacks on other aspects of the climate system e.g. surface temperatures and soil moisture. Hence, the last component of this project is to make coupled land-atmosphere simulations, thereby capturing all feedbacks. We will achieve this through our existing and on-going collaboration with the Hadley Centre (a world leading centre for modelling the climate system, who make predictions with their family of GCMs). This link will allow a final assessment to be made of whether the Arctic land-surface could pass an unwelcome climate 'tipping point', and thus feedback on existing warming, either locally through enhancing warming further or through the global C cycle.

人为燃烧化石燃料正在通过提高大气中的二氧化碳浓度来影响气候系统。但是，在强制气候变化的情况下，自然地球系统的某些方面会对碳循环产生重大影响吗？这种气候-碳(C)循环反馈可能是积极的--也就是说，它们可能会导致自然系统目前减轻人为二氧化碳排放的能力降低，甚至可能迫使自然系统成为二氧化碳的直接来源。这种积极的反馈是一个主要的令人担忧的原因，它们的启动可以被视为气候‘临界点’。有人假设，北极陆地表面可能是这样的“转折点”，全球变暖足以导致土壤碳流失，而不是通过增强冻土带(灌木)和北方森林在更温暖、富含二氧化碳的环境中生长，导致土壤碳的额外减少。此外，气候变暖将对气候变化和气候变化产生影响，从而影响能源和水循环，北纬地区的积雪减少会降低地表反射率，从而导致额外的变暖。事实上，能源、水和碳循环都是紧密联系在一起的，需要进行交互建模，以提供对未来的可靠估计。全球循环模型(GCM)旨在模拟气候系统和全球碳循环，并在此过程中为气候系统中潜在的“临界点”提供指示。但他们对北极地区的预测只能与该地区陆地表面模型中描述的水文、生态和能源相互作用一样好。因此，这个项目有两个目标--在陆地表面模型中提供更多的物理真实感，然后看看这种增强对模拟的未来气候有何影响。北极地区是否最终会通过增加未来大气二氧化碳的水平来加剧人类引起的气候变化？对北极地区的陆地表面进行建模是很复杂的。为了正确理解这一点，我们需要捕捉到植被如何在更温暖的环境中生长和扩展，以及这可能如何改变土壤中的碳储量。我们还需要模拟雪与植被的相互作用--雪覆盖将随气候变化，并将影响能量输入、水循环、冻土和植被分布。例如，较深的积雪将出现在植被较高的地区，因此植被结构不仅会影响积雪融化的时间，还会影响热量状况，因为较深的积雪实际上将土壤隔绝。因此，这会对土壤呼吸和植被生长产生连锁反应。该项目将对所有这些特征进行动态建模，以便能够评估未来气温和降雪模式对北极生态系统的影响。将广泛使用过去十年，特别是国际极地年由私营部门和其他机构开发的现有观测数据集。关于北极陆地表面的这一新知识将在泛北极格网模拟系统中引入。将综合当地和区域的行为，以确定陆地-大气二氧化碳净通量。然而，未来陆地表面行为的重大变化可能会对气候系统的其他方面产生强烈的反馈作用，例如地表温度和土壤湿度。因此，这个项目的最后一个组成部分是进行陆地-大气耦合模拟，从而捕获所有反馈。我们将通过与哈德利中心(一个世界领先的气候系统建模中心，他们与他们的GCM家族进行预测)现有的和正在进行的合作来实现这一点。这一联系将允许对北极陆地表面是否可能通过一个不受欢迎的气候“临界点”进行最终评估，从而对现有变暖做出反馈，要么是通过进一步加强局部变暖，要么是通过全球碳循环。