VOLCANIC CLASSIC: VOLCANIC eruptions and CLimAte response - Stratospheric Sulfate isotopes in Ice Cores, data assimilation, and climate sensitivity

地球气候对扰动有何反应？尽管做了几十年的工作，但这个根本问题仍然很难回答，因为对外部强迫的广泛气候敏感性仍然坚持使用最先进的模型。为了提高对气候系统的了解，缩小未来气候预测中的不确定性范围，需要创新的新方法。在这里，我提出了一种新的战略，通过利用主要火山喷发的记录，对气候模型和对气候敏感性的紧急约束进行独特的新测试。火山喷发对气候产生巨大影响，因为它们的硫酸盐气溶胶反射进入的阳光，在1-5年的时间尺度上驱动突然冷却。然而，我们目前阅读这一记录的能力受到火山强迫(火山喷发对即将到来的辐射的影响--主要是平流层硫酸盐的作用)和全球气候反应的不确定性的限制。通过使用尖端的新技术来测量冰芯中的硫同位素，我将唯一地约束平流层硫酸盐以及喷发的纬度和季节，转变对过去火山强迫的知识。我将把这与新的和改进的全球气候反应重建进行比较，这种重建是通过将新的全球分布的古气候记录纳入模式数据同化产品而实现的。通过研究过去2000年233次大喷发中每一次的气候反应，我将提供对火山气候敏感性的强有力的观测约束。我将用它们在最先进的气候模型中测试敏感度和反馈。这些测试将使人们了解当前模型对气溶胶的广泛敏感性，以及对有争议的地球工程方案的辩论。随着对火山和二氧化碳的模型反应联系在一起，这项工作最终将用于细化对二氧化碳上升的敏感范围，并改进对未来气候的预测。

How does Earth's climate respond to perturbation? Despite decades of work, this fundamental question remains difficult to answer, with a wide range of climate sensitivities to external forcing persisting in state-of-the-art models. To improve understanding of the climate system and narrow the range of uncertainties in future climate projections, innovative new approaches are required. Here I propose a novel strategy that will provide unique new tests of climate models and emergent constraints on climate sensitivity, by harnessing the record of major volcanic eruptions.Volcanic eruptions exert an enormous influence on climate, as their sulfate aerosols reflect incoming sunlight, driving abrupt cooling on timescales of 1-5 years. However our ability to read this record is currently limited by uncertainties in volcanic forcing (the impact of eruptions on incoming radiation - primarily a function of stratospheric sulfate) and global climate response. By using cutting edge new technology to measure sulfur isotopes in ice cores, I will uniquely constrain stratospheric sulfate and eruption latitude and season, transforming knowledge of past volcanic forcing. I will compare this to new and improved reconstructions of global climate response, achieved by incorporating new, globally-distributed paleoclimate records into model-data assimilation products. By examining the climate response to each of the 233 major eruptions of the last 2000 years, I will provide robust observational constraints on volcanic climate sensitivity. I will use these to test sensitivity and feedbacks in state-of-the-art climate models. These tests will inform both understanding of the wide range of sensitivity to aerosols in current models and the debate on controversial geoengineering schemes. As model response to volcanoes and CO2 are linked, this work will ultimately be used to refine the range of sensitivity to CO2 rise and improve projections of future climate.