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

[05:19415]热带安第斯山脉是全球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观点相一致。因此，整个热带安第斯山脉的冰川正在消退，这可能对饮用水、灌溉用水、采矿用水和水力发电用水的供应造成严重后果。一般循环模型（GCMs）的运行等级为2。二氧化碳情景预测，到本世纪末，全球气温将再上升2.5摄氏度以上。然而，这些未来的预估存在很大的不确定性，特别是因为gcm的粗分辨率不足以解决与陡峭的安第斯地形相关的中尺度和局地尺度环流特征。为了准确地了解和预测未来的气候变化及其对热带安第斯山脉冰川的影响，需要更高分辨率的模型和对温度以外的其他变量的更好的模拟。我们建议使用区域气候模式（PRECIS）模拟安第斯山脉在当前条件（1961- 1990年和1958-2001年）和两种不同的IPCC-SRES排放情景（2071-2100年）下的气候变率和变化，以更好地了解未来气候变化如何影响热带安第斯山脉冰川。我们的区域气候模式的结果将与来自太空的观测数据进行验证，然后将其作为冰川气候模式（ITGG 2.0）的输入，以模拟冰川物质平衡将如何受到未来气候变化的影响。所选冰川的模拟物质平衡将与热带安第斯山脉的观测记录进行比较，以验证我们的结果的准确性。为了更好地了解冰川退缩的后果，ITGG 2.0模型还将用于模拟安第斯流域径流的变化。我们提出的研究的预期结果是：1)高分辨率模式的使用将改善该地区复杂地形的气候模拟，并产生比迄今为止从gcm获得的更准确的未来气候变化预测。2)利用观测数据对模型进行深入验证将有助于更好地评估模型的性能（对于RCM和ITGG 2.0）。3)我们将首次建立关于21世纪末该地区冰川作用和径流变化的可靠预估。这对该地区预计的未来水资源短缺具有重要影响，并将为实施适应和缓解战略提供急需的信息。4)使用区域气候模式数据代替航线分辨率再分析数据作为ITGG 2.0模式的输入，将显著改善模式。我们坚信，我们提出的研究解决了与热带安第斯山脉未来气候变化相关的一个关键问题，这是一个具有高度科学兴趣的问题，也是该地区主要的社会经济相关性。未来发生水危机的可能性是显而易见的，由于观测到的冰川迅速退缩，这种缺水与预计的未来径流变化有关。因此，这项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而广泛的影响。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，就无法实施减缓和适应战略。

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.