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.

化石燃料的人为燃烧正在通过升高的大气二氧化碳浓度来影响气候系统。但是，自然地球系统是否有各个方面，当受到气候变化强迫时，会对碳循环产生重大影响？这种气候 - 碳（C）循环反馈可能是积极的 - 也就是说，它们可能会降低自然系统减轻人为CO2排放的当前能力，甚至可能迫使天然系统成为CO2的直接来源。这种积极的反馈是引起人们关注的主要原因，它们的启动可以被视为气候“临界点”。有人认为，北极陆地表面可能是这样的“临界点”，因此，全球变暖足以通过增强的苔原（灌木）（灌木）和北方森林在温暖的，二氧化碳增强的环境中诱导c的土壤C损失。此外，温暖的气候将影响能量和水周期的水，北纬度地区的积雪覆盖率较小，从而降低了表面反射率，从而诱发了额外的变暖。实际上，能量，水和C周期都紧密相连，需要进行交互建模，以提供对未来的强大估计。全球循环模型（GCM）旨在模仿气候系统和全球碳循环，在此过程中，为气候系统中的潜在“临界点”提供了指针。但是，它们对北极区域的预测仅与该地区的土地表面模型中描述的水文学，生态和能量相互作用一样好。因此，该项目有两个目标 - 在陆地表面模型中提供更多的物理现实主义，然后看看这种增强如何影响建模的未来气候。北极地区是否最终通过提高未来大气二氧化碳水平来增强人类引起的气候变化？建模北极区域的土地表面很复杂。为了正确解决这一问题，我们将需要捕获植被在温暖的环境中如何生长和扩展，以及如何改变土壤C种。我们还需要对雪与植被相互作用进行建模 - 积雪将随着气候的变化而变化，并会影响能量输入，水循环，冷冻地面和植被分布。例如，在高植被的地区将发生更深的积雪，因此植被结构不仅会影响雪融化的时机，而且会影响热雪的最深降雪实际上可以绝缘土壤。因此，对土壤呼吸和植被生长有敲门效应。该项目将动态地对所有这些特征进行建模，以便可以评估未来温度和降雪模式对北极生态系统的影响。在过去的十年中，尤其是国际极性年，PIS和其他人开发的现有观察数据集将广泛使用。对北极土地表面的新知识将在泛北极网格建模系统中引入。局部和区域行为将集成以确定净土地大气二氧化碳通量。但是，土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。表面温度和土壤水分。因此，该项目的最后一个组成部分是进行耦合的土地大气模拟，从而捕获所有反馈。我们将通过与哈德利中心（Hadley Center）的现有和持续的合作来实现这一目标（世界领先的气候系统建模中心，他们与GCM的家人进行预测）。该链接将允许对北极土地表面是否可以通过不受欢迎的气候“临界点”进行最终评估，从而通过进一步增强变暖或通过全球C周期在当地增强变暖，从而反馈现有变暖。