Impacts of Pacific Ocean warming trends (ImPOse)

太平洋变暖趋势的影响 (ImPOse)

• 批准号: NE/W005239/1
• 负责人: Robin Chadwick
• 金额: $ 82.45万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FW005239%2F1
• 关键词: Impacts; Pacific; Ocean; warming; trends

The tropical Pacific Ocean is at the heart of global climate variability and change. El Niño and La Niña events consist of large-scale sea surface temperature (SST) anomalies in the equatorial Pacific. By driving global-scale changes in the atmospheric circulation, El Niño and La Niña events cause floods, droughts and temperature extremes across the world. On decadal and longer timescales, even small SST changes in the tropical Pacific can be associated with devastating long-term changes in rainfall patterns, such as the US "Dust-Bowl" drought of the 1930s. Tropical Pacific SSTs are also a primary control of global mean temperature variability, and were a major driver of the "slowdown" in global warming in the early years of this century. The response of the tropical Pacific to climate change is therefore of immense interest and importance.Climate models consistently project that eastern equatorial Pacific SSTs warm more than surrounding regions under climate change, which is similar to the pattern of SST warming during El Niño events, and acts to reinforce SST anomalies during El Niños. Such behaviour leads to projections with a greater frequency of extreme El Niño events, affecting weather extremes globally. This pattern of SST warming also greatly influences the global pattern of mean precipitation changes and strongly modulates global temperature change (climate sensitivity). However, observations over the last 50-100 years suggest only a small eastern equatorial Pacific warming trend - which is greatly at odds with the strong trends produced by climate model simulations, potentially invalidating many aspects of future climate projections. The conflict between modelled and observed trends holds across multiple SST datasets and several generations of climate models, including our new pilot analysis of state-of-the-art climate models. These results suggest that climate models are fundamentally misrepresenting the tropical Pacific response to climate change: consequences include projecting incorrect changes in global temperature change, global rainfall patterns, global circulation responses, tropical cyclone activity and air-sea CO2 fluxes.ImPOse will provide the focused, coordinated approach that is necessary (but has to date been missing) to identify the root causes of model errors in tropical Pacific SST trends, by testing multiple hypotheses using state-of-the-art models/observations and targeted idealised experiments, together with an explicit plan of how to correct model projections by feeding results directly into model development and identifying possible emergent constraints. It is crucial that this serious tropical Pacific error and its impacts on global and regional climate projections are assessed, its cause isolated, and a pathway to correcting it identified.ImPOse consists of three complementary parts:1) Analysis of long-term tropical Pacific trends in state-of-the-art observational datasets and climate models. Through careful analysis of these datasets, including testing several existing hypotheses, we will determine why modelled and observed trends disagree.2) Idealised climate model experiments to determine fundamental causes of tropical Pacific model biases in present-day climate. Model biases in the tropical Pacific response to climate change are likely to be strongly linked to biases in the simulation of present-day climate. Targeted model experiments will be performed to test hypotheses about the causes of present-day biases, including both structural and parameter-based causes.3) Climate model experiments to determine the global impacts of tropical Pacific SST trends. By comparing the effect of imposed observed vs modelled tropical Pacific SST in a set of climate model experiments, we will determine the global impact of tropical Pacific climate change and assess the credibility of CMIP6 climate change projections.

热带太平洋是全球气候变异和变化的中心。厄尔尼诺和拉尼娜事件是指赤道太平洋的大规模海表温度异常。厄尔尼诺和拉尼娜现象通过推动全球范围的大气环流变化，在世界各地造成洪水、干旱和极端气温。在十年和更长的时间尺度上，即使热带太平洋的SST变化很小，也可能与降雨模式的破坏性长期变化有关，例如20世纪30年代美国的“Dust-Bowl”干旱。热带太平洋海温也是全球平均温度变化的主要控制因素，是本世纪初全球变暖“减缓”的主要驱动因素。气候模式一致预测，在气候变化下，赤道东太平洋海温比周围地区更暖，这与厄尔尼诺事件期间海温变暖的模式相似，并在厄尔尼诺期间加强海温异常。这种行为导致预测出现更频繁的极端厄尔尼诺现象，影响全球极端天气。这种SST变暖模式也极大地影响了全球平均降水变化模式，并强烈调节全球温度变化（气候敏感性）。然而，过去50-100年的观测表明，赤道东太平洋只有一个小的变暖趋势-这与气候模型模拟产生的强烈趋势大相径庭，可能使未来气候预测的许多方面无效。模拟和观测趋势之间的冲突在多个SST数据集和几代气候模型中存在，包括我们对最先进气候模型的新试点分析。这些结果表明，气候模型从根本上歪曲了热带太平洋对气候变化的反应：结果包括预测全球温度变化、全球降雨模式、全球环流响应、热带气旋活动和海气CO2通量的错误变化。ImPOse将提供重点，协调一致的方法是必要的（但迄今为止一直缺失），以确定热带太平洋SST趋势中模式误差的根本原因，通过使用最先进的模型/观察和有针对性的理想化实验来测试多个假设，以及如何通过将结果直接输入模型开发并识别可能的紧急约束来纠正模型预测的明确计划。重要的是要评估这一严重的热带太平洋误差及其对全球和区域气候预测的影响，找出其原因，并确定纠正的途径。ImPOse由三个互补部分组成：1）在最先进的观测数据集和气候模式中分析热带太平洋的长期趋势。通过对这些数据集的仔细分析，包括测试几个现有的假设，我们将确定为什么模拟和观察到的趋势不一致。2）理想化的气候模式实验，以确定热带太平洋模式在当今气候中偏差的根本原因。热带太平洋对气候变化反应的模型偏差可能与当今气候模拟的偏差密切相关。将进行有针对性的模式试验，以检验关于当前偏差原因的假设，包括结构和参数原因。3）气候模式试验，以确定热带太平洋SST趋势的全球影响。通过在一组气候模式实验中比较强加的观测与模拟热带太平洋SST的影响，我们将确定热带太平洋气候变化的全球影响，并评估CMIP 6气候变化预测的可信度。