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Understanding past, present and future climate change in the 'Greater Mediterranean' area: Building confidence in uncertain climate projections

了解“大地中海”地区过去、现在和未来的气候变化：建立对不确定气候预测的信心

基本信息

批准号：
NE/H015841/1
负责人：
David Brayshaw
金额：
$ 31.33万
依托单位：
University of Reading
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH015841%2F1
关键词：
Understanding past present future climate

项目摘要

One of the most important challenges facing society today is the question of how best to adapt to climate change. This adaption usually takes place locally, on a regional or national level, and reliable projections of regional climate change are clearly a prerequisite for developing a robust adaption strategy. The need for this information is perhaps nowhere more pressing than in the Mediterranean, which is an area anticipated to be a hotspot of climate change, and where the combined pressure of a changing climate coupled to a rapidly increasing population is expected to cause increased drought, crop failure and environmentally-forced human migration in the coming century. Clearly the success (or otherwise) of climate change adaption in the 'Greater Mediterranean' region (stretching from Europe to North Africa and from the eastern North Atlantic to the Middle East) will have profound social impacts on both global and regional scales. In order to produce reliable projections of climate change, it is not sufficient just to run climate models, even state-of-the-art ones. While over 90% of the climate models used in the recent IPCC fourth assessment report (Solomon et al, 2007) show a strong reduction in winter precipitation over much of the Mediterranean (mean reduction ~20%), the detailed patterns will depend on the response of the storm tracks which describe the eastward passage of cyclonic weather systems across the North Atlantic and the Mediterranean basins. As such, it is difficult to reconcile the inter-model agreement on 21st century precipitation change over the Mediterranean with the inter-model disagreement on the future of the North Atlantic and Mediterranean storm tracks. There remain too many unanswered questions regarding the behaviour of these storm tracks, raising the important question: How much confidence should we have in projections of Mediterranean climate change if the fundamental processes controlling the Mediterranean storm track on climate timescales are poorly understood? This question applies as much to the use of climate models for seasonal forecasting or for the reconstruction past climates as it does to 21st century climates. At present there is a poor understanding of how the Mediterranean storm track is 'controlled' by the interaction of local processes (e.g., mountains, land-sea contrast, moisture availability) and the large-scale atmospheric flow (e.g., the circulation over the North Atlantic area). Case studies, conceptual models and theory provide some insight, but it is essential that this knowledge can be applied more generally to the complex atmospheric flow patterns seen in the Mediterranean. There is therefore a pressing need to be able to bridge the gap between theoretical concepts or case-studies and the complex situations seen in observations or state-of-the-art climate model projections. This proposal sets out to address this important gap in our understanding of the Mediterranean storm track. In particular, it proposes a systematic investigation of the fundamental processes using advanced climate models but with simplified surface properties that capture the essence of the real system while reducing unnecessary spatial complexity. The physical understanding developed in this manner will then be used to better examine existing state-of-the-art climate projections for the 21st century, present day variability, and the changes seen over the last 12,000 years. The understanding gained will be of wide practical use (see the Impacts summary and plan). Extensive links, both with climate scientists and also across disciplines, are planned and have already begun to be established in order to communicate the research effectively.

当今社会面临的最重要挑战之一是如何最好地适应气候变化的问题。这种适应通常发生在当地、区域或国家层面，对区域气候变化的可靠预测显然是制定强有力的适应战略的先决条件。对这些信息的需求或许比地中海更为迫切，地中海地区预计将成为气候变化的热点地区，气候变化与人口迅速增长的综合压力预计将导致下个世纪干旱、作物歉收和环境迫使的人类迁徙加剧。显然，“大地中海”地区（从欧洲延伸到北非，从北大西洋东部延伸到中东）气候变化适应的成功（或失败）将对全球和区域规模产生深远的社会影响。为了对气候变化进行可靠的预测，仅仅运行气候模型是不够的，即使是最先进的模型也是不够的。虽然最近的 IPCC 第四次评估报告（Solomon 等人，2007 年）中使用的超过 90% 的气候模型显示，地中海大部分地区冬季降水量大幅减少（平均减少约 20%），但详细模式将取决于风暴路径的响应，风暴路径描述了气旋天气系统向东穿过北大西洋和地中海盆地的情况。因此，很难调和关于 21 世纪地中海降水变化的模型间协议与关于北大西洋和地中海风暴路径未来的模型间分歧。关于这些风暴路径的行为仍然有太多未解答的问题，这就提出了一个重要的问题：如果对气候时间尺度上控制地中海风暴路径的基本过程知之甚少，我们对地中海气候变化的预测应该有多大的信心？这个问题既适用于使用气候模型进行季节预测或重建过去的气候，也适用于 21 世纪的气候。目前，人们对地中海风暴路径如何通过局部过程（例如山脉、陆地-海洋对比、水分可用性）和大规模大气流动（例如北大西洋地区上空的环流）的相互作用进行“控制”还知之甚少。案例研究、概念模型和理论提供了一些见解，但至关重要的是，这些知识可以更广泛地应用于地中海复杂的大气流动模式。因此，迫切需要能够弥合理论概念或案例研究与观测或最先进的气候模型预测中看到的复杂情况之间的差距。该提案旨在解决我们对地中海风暴路径理解中的这一重要差距。特别是，它提出使用先进的气候模型对基本过程进行系统的研究，但具有简化的表面特性，可以捕捉真实系统的本质，同时减少不必要的空间复杂性。以这种方式发展起来的物理理解将被用来更好地研究现有的 21 世纪最先进的气候预测、当今的变化以及过去 12,000 年的变化。获得的理解将具有广泛的实际用途（参见影响摘要和计划）。为了有效地交流研究成果，与气候科学家以及跨学科的广泛联系已经计划并已经开始建立。