Studies of Multi-decadal Variability in Climate Records

在这笔资金下，首席研究员（PI）将研究全球记录中的振荡及其对推断的人为变暖趋势的影响。特别是，将审查70年尺度的全球变率与大西洋多年代际振荡之间的关系。由于这种大幅度低频变率的存在，数据中人为趋势的推断往往变得复杂，因为其谷峰偏移是过去150年观测到的变暖趋势的一半。当它被添加到潜在的人为变暖趋势中时，它造成了自1978年以来的加速变暖和20世纪70年代经历的冷却。世纪早期的变暖很可能主要是由这种振荡的前一个正阶段造成的。全球振荡似乎起源于北大西洋海面温度的变化，是温盐环流高频变化的一种表现，但所涉及的机制尚未完全确定。鉴于观测时间跨度有限，目前的数据分析方法可能不足以研究这种低频变异。新的方法是分析全球数据记录，提供一个量化的错误，因为即使是最长的准全球气候记录（1850年至今）也不够长。另一方面，将研究英格兰中部（1659年至今）更长的仪器记录和格陵兰岛几个更长的冰芯数据记录，以确定这种振荡在前工业时代的存在。将更详细地研究全球温度和海平面压力，以了解信号从大西洋到太平洋的传播。将对北极融冰进行相关研究，以确定融冰是否作为建立振荡所必需的负反馈参与，该项目将确定北大西洋数十年自然变化的重要性，从而改进对气候变化的探测和归因。这是气候科学中的一个重要问题，具有广泛的影响。

Under this funding, the Principal Investigator (PI) will study oscillations in the global record and their effect on the deduced anthropogenic warming trend. In particular, the relationship between global variability at a 70-year scale and the Atlantic Multi-decadal Oscillation will be examined. The deduction of the anthropogenic trend in data is often complicated by the presence of this large amplitude low-frequency variability, since its trough-to-peak excursion is one half of the observed warming trend for the past 150 years. When it is added to the underlying anthropogenic warming trend, it creates the accelerated warming seen since 1978 and the cooling experienced in the 1970s. The early twentieth century warming was probably largely caused by the previous positive phase of this oscillation. The global oscillation appears to have its origin in the sea surface temperature variability of the North Atlantic, as a manifestation of a high frequency variability of the thermohaline circulation, but the mechanisms involved are not yet well established. Current data analysis methods may not be adequate for studying such low-frequency variability given the limited time span of the observation. New methods are for analyzing the global data record, to provide a quantification of errors due to the fact that even the longest quasi-global climate records (1850-present) are not long enough. On the other hand, a longer instrumental record at Central England (1659-present) and several even longer ice-core data records from Greenland will be studied to establish the existence of this oscillation in the pre-industrial era. The global temperature and sea-level pressure will be studied in more detail to understand the propagation of the signal from the Atlantic to the Pacific. Correlation studies will be performed with the Arctic ice-melt to determine if the latter is involved as a negative feedback necessary to establish an oscillation.The project will establish the significance of multidecadal natural variability in the North Atlantic and thus improve the detection and attribution of climate change. This is an important problem in climate science that has substantial broader impacts.