UKRI-Norway: Figuring Out how to Reconstruct Common Era forcing of climate by VOLcanoes with novel data and modelling approaches (FORCE-VOL)

UKRI-挪威：弄清楚如何利用新颖的数据和建模方法重建共同时代火山对气候的强迫（FORCE-VOL）

• 批准号: NE/Y001044/1
• 负责人: Elizabeth Thomas
• 金额: $ 8.41万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY001044%2F1
• 关键词: UKRI; Norway; Figuring; Out; how

Large volcanic eruptions can have a major impact on climate, due to the emission of sulfur gases, which form small droplets (aerosols) that reflect incoming sunlight and cool the Earth's surface. When these aerosols form in the upper levels of the atmosphere (the stratosphere, 15-50 km altitude) they remain there for several years, resulting in pronounced global cooling. Indeed, this phenomenon has inspired controversial proposals to cool the planet to combat global warming through artificial stratospheric sulfur injections. However, despite its scientific and societal significance, understanding of volcanic impacts on climate is highly uncertain, due to the limited observational record of large explosive volcanism: only two eruptions, Pinatubo in 1991 and El Chichón in 1982, have impacted global climate within the satellite era. These eruptions are at least an order of magnitude smaller than the largest eruptions in the historical record, and so are not representative of the scope of how volcanoes can impact our climate. This makes it challenging to understand, and prepare for, the climatic and societal impact of large eruptions in the future. The limited observational record of volcanic sulfur emissions also creates a major issue for climate models, which need to know how much sulfur to add to their computerised stratospheres in order to mimic historical climate change events. To address these challenges, we are proposing a new way to reconstruct the amount of stratospheric sulfate from large eruptions over the last 2000 years, based on the record of volcanic sulfate found in polar ice cores. Although this approach is widely used, at present there are major uncertainties in how to convert the amount of sulfate found in ice cores into the original amount of sulfate that was in the stratosphere.This project will substantially improve this conversion - known as the "transfer function" - by using new ice cores, new measurement techniques, and new modelling approaches. First, we will make detailed comparisons of the amount of sulfate in the ice to measurements of the amount of sulfur that went into the stratosphere for eruptions during the last 150 years, a time period in which direct observations of the atmosphere (either by satellites or instruments that measure sunlight) exist. Compared to the last time this calibration was done, the number of available ice cores has grown from 11 to 90, allowing for much better spatial coverage and more representative data. We also have a new technique that measures sulfur isotopes to allow us to distinguish the climatically-important stratospheric sulfate from other sources of sulfate to the ice sheets, further improving the accuracy of the calibration. A new computer modelling approach will also be used to make sure that the transfer function is applicable to a broad range of different eruption characteristics (such as the size, season, and latitude of the eruption), and to help us characterise the transfer function's uncertainty.The insights from the ice core calibration and the modelling will be combined to generate a new record of stratospheric sulfate from volcanic eruptions over the last 2000 years. This record will be used widely in climate model simulations, including those used to inform the International Panel on Climate Change (IPCC). Indeed this work may lead to improvements in climate modelling, as if the amount of sulfate to be added to the models for historical eruptions is better known, we should be able to make better assessments of which models most accurately match the associated changes in climate. Looking forward, our work will also be valuable for policy makers and insurance companies interested in natural hazards, as it will allow them to better understand the frequency and potential impacts of the major eruptions that will occur in our future.

大型火山喷发会对气候产生重大影响，因为硫磺气体的排放会形成小液滴（气溶胶），当这些气溶胶在大气高层（平流层）中形成时，会反射入射的阳光并冷却地球表面。 （海拔 15-50 公里）它们会在那里停留数年，导致全球明显变冷。事实上，这种现象引发了一些有争议的提议，即通过人工平流层来冷却地球以应对全球变暖。然而，尽管火山喷发具有科学和社会意义，但由于大型火山喷发的观测记录有限，人们对火山对气候影响的了解仍高度不确定：只有 1991 年的皮纳图博火山和 1982 年的奇琼火山两次喷发对全球气候产生了影响。这些火山喷发至少比历史记录中最大的火山喷发小一个数量级，因此不能代表火山影响的范围。这使得了解和应对未来大规模火山喷发对气候和社会的影响变得具有挑战性，对火山硫排放的有限观测记录也给气候模型带来了一个主要问题，因为气候模型需要知道硫的含量。添加到计算机化的平流层中，以模拟历史气候变化事件。为了应对这些挑战，我们提出了一种新方法来重建过去大规模喷发产生的平流层硫酸盐量。 2000年以来，根据极地冰芯中发现的火山硫酸盐的记录，虽然这种方法被广泛使用，但目前如何将冰芯中发现的硫酸盐量转换为原始的硫酸盐量存在很大的不确定性。该项目将通过使用新的冰芯、新的测量技术和新的建模方法来大幅改进这种转换（称为“传递函数”）。将冰中硫酸盐的含量与过去 150 年中进入平流层火山喷发的硫含量的测量结果进行比较，在过去 150 年中，存在对大气的直接观测（通过卫星或测量阳光的仪器）。上次进行校准时，可用冰芯的数量从 11 个增加到 90 个，从而获得更好的空间覆盖范围和更具代表性的数据。使我们能够将对气候重要的平流层硫酸盐与冰盖的其他硫酸盐来源区分开来，进一步提高校准的准确性，还将使用新的计算机建模方法来确保传递函数适用于广泛的范围。不同喷发特征（例如喷发的规模、季节和纬度），并帮助我们表征传递函数的不确定性。冰芯校准和建模的见解将结合起来生成新的记录该记录将广泛用于气候模型模拟，包括为国际气候变化专门委员会 (IPCC) 提供信息。事实上，这项工作可能会改进气候模型。如果添加到历史喷发模型中的硫酸盐量更加清楚，我们应该能够更好地评估哪些模型最准确地匹配相关的气候变化。展望未来，我们的工作也将是这样的。对于对自然灾害感兴趣的政策制定者和保险公司来说很有价值，因为这将使他们能够更好地了解未来发生的重大火山爆发的频率和潜在影响。