NOAA Southwest Fisheries Science Center, Monterey, CA, USA.
NOAA Earth System Research Laboratory, Boulder, CO, USA.
Nature. 2020 Aug;584(7819):82-86. doi: 10.1038/s41586-020-2534-z. Epub 2020 Aug 5.
Marine heatwaves (MHWs)-discrete but prolonged periods of anomalously warm ocean temperatures-can drastically alter ocean ecosystems, with profound ecological and socioeconomic impacts. Considerable effort has been directed at understanding the patterns, drivers and trends of MHWs globally. Typically, MHWs are characterized on the basis of their intensity and persistence at a given location-an approach that is particularly relevant for corals and other sessile organisms that must endure increased temperatures. However, many ecologically and commercially important marine species respond to environmental disruptions by relocating to favourable habitats, and dramatic range shifts of mobile marine species are among the conspicuous impacts of MHWs. Whereas spatial temperature shifts have been studied extensively in the context of long-term warming trends, they are unaccounted for in existing global MHW analyses. Here we introduce thermal displacement as a metric that characterizes MHWs by the spatial shifts of surface temperature contours, instead of by local temperature anomalies, and use an observation-based global sea surface temperature dataset to calculate thermal displacements for all MHWs from 1982 to 2019. We show that thermal displacements during MHWs vary from tens to thousands of kilometres across the world's oceans and do not correlate spatially with MHW intensity. Furthermore, short-term thermal displacements during MHWs are of comparable magnitude to century-scale shifts inferred from warming trends, although their global spatial patterns are very different. These results expand our understanding of MHWs and their potential impacts on marine species, revealing which regions are most susceptible to thermal displacement, and how such shifts may change under projected ocean warming. The findings also highlight the need for marine resource management to account for MHW-driven spatial shifts, which are of comparable scale to those associated with long-term climate change and are already happening.
海洋热浪（MHWs）——异常温暖的海洋温度的离散但持续时间较长的时期——可以极大地改变海洋生态系统，产生深远的生态和社会经济影响。人们已经投入了相当大的努力来了解全球海洋热浪的模式、驱动因素和趋势。通常，海洋热浪是根据其在给定地点的强度和持续时间来描述的，这种方法对于珊瑚和其他必须忍受温度升高的固着生物尤其相关。然而，许多具有生态和商业重要性的海洋物种通过迁移到有利的栖息地来应对环境干扰，而移动海洋物种的剧烈范围转移是海洋热浪的显著影响之一。虽然空间温度变化在长期变暖趋势的背景下已经得到了广泛的研究，但在现有的全球海洋热浪分析中却没有考虑到这些变化。在这里，我们引入热位移作为一种度量，通过表面温度轮廓的空间位移来描述海洋热浪，而不是通过局部温度异常来描述，并用基于观测的全球海表温度数据集来计算 1982 年至 2019 年所有海洋热浪的热位移。我们表明，海洋热浪期间的热位移在全球海洋中从几十公里到几千公里不等，与海洋热浪强度在空间上没有相关性。此外，海洋热浪期间的短期热位移与从变暖趋势推断出的世纪尺度位移相当，尽管它们的全球空间模式非常不同。这些结果扩展了我们对海洋热浪及其对海洋物种潜在影响的理解，揭示了哪些地区最容易受到热位移的影响，以及在预计的海洋变暖下这些位移可能会如何变化。这些发现还强调了海洋资源管理需要考虑海洋热浪驱动的空间位移，这些位移与长期气候变化相关的位移具有可比性，并且已经在发生。
