Impacts and Consequences of Predicted Climate Change on Andean Glaciation and Runoff

热带安第斯山脉是最近气候变化最明显的地区之一，这与延伸到对流层中部的高海拔山脉将经历更大变暖的概念一致。因此，整个热带安第斯山脉的冰川正在消退，这可能会对饮用水以及灌溉、采矿和水电生产的水的可用性造成严重影响。运行在2.CO2情景下的一般环流模型(GCM)预测，到本世纪末，全球变暖将增加超过2.5摄氏度。然而，这些未来预测存在很大的不确定性，特别是因为GCM的粗略分辨率不足以解决与陡峭地形和地形相关的中尺度和局地尺度环流特征。为了准确地理解和预测未来气候变化及其对热带安第斯冰川的影响，需要更高分辨率的模型和更好地模拟其他温度变量。我们建议使用区域气候模式(PRECIS)模拟当前条件(1961-90年和1958-2001年)和两种不同的IPCC-SRES排放情景(2071-2100)下安第斯山脉的气候变异性和变化，以更好地了解未来气候变化对热带安第斯冰川的影响。我们的区域气候模型的结果将通过空间观测数据进行验证，然后将其作为冰川-气候模型(ITGG 2.0)的输入，以模拟冰川质量平衡将如何受到未来气候变化的影响。选定冰川的模拟现今质量平衡将与热带安得斯泰斯的观测记录进行比较，以验证我们结果的准确性。为了更好地了解冰川退缩的后果，还将使用ITGG2.0模型来模拟安第斯流域径流的变化。我们拟议研究的预期结果是：1)高分辨率模式的使用将改进这一复杂地形地区的气候模拟，并产生比GCM迄今提供的对未来气候变化更准确的预测。2)使用观测数据进行深入的模式验证将导致对模式性能的更好评估(对于RCM和ITGG 2.0)。3)我们将首次建立对21世纪末该地区冰川和径流将如何变化的可靠预测。4)最后，我们预计使用区域气候模式数据而不是航向分辨率重新分析数据作为ITGG 2.0模式的输入将显著改善模式。我们坚信，我们拟议的研究解决了与热带安第斯山脉未来气候变化有关的一个关键问题，这具有很高的科学价值，但也具有该区域的主要社会经济意义。未来出现水危机的可能性是显而易见的，这种缺水与预计未来径流的变化有关，这是由于观察到的冰川迅速消退。因此，这一建议的科学价值在于更好地了解与热带安第斯冰川消失有关的机制和后果。关于冰川消退的速度和程度以及这将对安第斯山脉未来的径流和水资源供应产生多大影响的知识的增加，将对当地经济和人口产生重大和广泛的影响。如果不能更好、更详细地了解未来气候变化将如何影响安第斯山脉的冰川和水文系统，就可以制定减缓和适应战略。

0519415VuilleThe tropical Andes are one of the regions of the globe where recent climate change ismost evident, consistent with the notion that high-elevation mountain ranges that extend into themid-troposphere will experience greater warming. As a result glaciers are receding throughout thetropical Andes, with potentially severe consequences for the availability of drinking water, andwater for irrigation, mining and hydropower production.General Circulation Models (GCMs) run with a 2.CO2 scenario predict an additionalwarming of more than 2.5.C by the end of the century. However large uncertainties exist aboutthese future projections, especially because the coarse resolution of GCMs is inadequate toresolve the meso- and local-scale circulation features associated with the steep Andeantopography. To accurately understand and predict future climate change and its impact on tropicalAndean glaciers, higher resolution models and a better simulation of variables other thantemperature are required.We propose to simulate climate variability and change in the Andes under both presentdayconditions (1961-90 and 1958-2001) and two different IPCC-SRES emission scenarios(2071-2100) with a regional climate model (PRECIS) to gain a better understanding of howfuture climate change might affect tropical Andean glaciers.Results from our regional climate model will be validated with observational data fromspace before they are used as input into a glacier-climate model (ITGG 2.0) to simulate howglacier mass balance will be affected by future climate change. The simulated present-day massbalance of selected glaciers will be compared with observational records from the tropical Andesto verify the accuracy of our results. To gain a better understanding of the consequences ofglacier retreat, the ITGG 2.0 model will also be used to simulate changes in runoff from Andeanwatersheds. The anticipated results of our proposed research are:1) The use of a high-resolution model will improve simulations of climate in this area of complexterrain and yield more accurate predictions of future climate change than are available to datefrom GCM.s.2) An in-depth model validation with observational data will lead to a better assessment of modelperformance (for both the RCM and the ITGG 2.0).3) We will for the first time establish robust projections of how glaciation and runoff will changein this region at the end of the 21st century. This has important implications for the anticipatedfuture water shortage in the region and will provide much needed information to implementadaptation and mitigation strategies.4) Finally we anticipate a significant model improvement as a result of using regional climatemodel data instead of course resolution reanalysis data as input into the ITGG 2.0 model.We strongly believe that our proposed research addresses a key issue related to futureclimate change in the tropical Andes, which is of high scientific interest but also of primarysocio-economic relevance for the region. The potential for a future water crisis is evident and thiswater shortage is related to a projected future change in runoff, due to the observed rapid glacierretreat. The scientific merit of this proposal is therefore to gain a better understanding of bothmechanisms and consequences related to the disappearance of tropical Andean glaciers. Thisincreased knowledge on how fast and how far glaciers will recede and how much this will affectfuture runoff and water availability from the Andes will have a significant and broad impact onlocal economies and populations. Without a better and much more detailed knowledge of howfuture climate change will affect glaciological and hydrological systems in the Andes, nomitigation and adaptation strategies can be put in place.