Abstract：
It has been proven that marine heatwaves (MHWs) have increased in frequency, duration, and intensity over the past few decades, and this trend will accelerate further under continued global warming. While more intense and frequent MHWs are an expected consequence of rising sea surface temperatures (SSTs) under continued global warming, it remains unclear to what degree per Celsius warming trend of SSTs contributes to the changes in the MHW metrics. Here, we focus on how the MHW metrics evolve with the SST warming trend by using an adaptive data analysis method based on observational datasets covering the past four decades. We find that the globally averaged increasing rates of the annual MHW frequency, duration, and maximum intensity are approximately 3.7 events, 7.5 days, and 2.2° Celsius per degree Celsius of SST rise, respectively. The increasing rates for the annual MHW days and the fraction of the spatial extents to the global ocean affected by MHWs are approximately 58.8 days and 13.9 % per degree Celsius of SST rise, respectively. Based on these observational-based increasing rates and the projected SST warming from the selected Coupled Model Intercomparison Project Phase 6 (CMIP6) models, the spatial distributions of changes in annual MHW days, frequency, and cumulative intensity are projected to exhibit 2-fold, 4-fold, and 6 to 8-fold increases under the three socioeconomic pathways (i.e., SSP126, SSP245, and SSP585), respectively. The globally averaged annual MHW days will increase to approximately 224.2 ± 26.9 days, and the largest changes are projected to occur in the northeast Pacific, the North Atlantic, the south Indian Oceans, and parts of the Southern Ocean, with approximately 14.8 ± 5.7 % of the global ocean reaching a permanent MHW state by the end of the twenty-first century under SSP585.
摘要：
已经证明，海洋热浪（MHW）的频率增加，持续时间,在过去的几十年里，在全球持续变暖的情况下，这一趋势将进一步加速。虽然在全球持续变暖的情况下，海表温度（SST）上升的预期结果是更强烈和频繁的MHW，目前尚不清楚SST的每摄氏度变暖趋势对MHW指标的变化有多大贡献.这里,我们通过使用基于过去四十年的观测数据集的自适应数据分析方法，重点研究MHW指标如何随着SST变暖趋势而演变。我们发现，全球平均每年MHW频率的增长率，持续时间,最大强度约为3.7个事件，7.5天,每摄氏度SST上升2.2摄氏度，分别。每年MHW日的增长率和受MHW影响的全球海洋的空间范围约为每摄氏度SST上升58.8天和13.9%，分别。基于这些基于观测的增长率和选定的耦合模型比对项目第6阶段（CMIP6）模型的预计SST变暖，年MHW日变化的空间分布，频率,累积强度预计为2倍，4倍，在三种社会经济途径下增加了6到8倍(即，SSP126、SSP245和SSP585),分别。全球平均每年MHW日将增加到大约224.2±26.9日，最大的变化预计将发生在东北太平洋，北大西洋,南印度洋，和南大洋的部分地区，在SSP585下，到二十一世纪末，全球约有14.8±5.7％的海洋达到永久的MHW状态。
