Global Warming has Increased the Distance Traveled by Marine Heatwaves. Issue 2 (24th January 2023)

• Record Type: Journal Article
• Authors: He, Yongli; Zhang, Boyuan; Xia, Zihan; Wang, Shanshan; Guan, Xiaodan
• Is Part Of: Geophysical research letters. Volume 50:Issue 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-24
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2022GL102032
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Due to the destructive effects of marine heatwaves (MHWs) on marine ecosystems and local economies, whether they become more frequent and stronger under global warming has attracted much attention. The proposed event‐based algorithm identifies 3, 843 MHWs during 1982–2020. Except for the MHW frequency, the global averaged duration, intensity, area and moving distance increased significantly. The contributions of the frequency and mean projection area to the total projection area were further investigated from the four categories of MHWs. The results showed that for moderate MHWs, frequency contributes more than the mean projection area to the increase in projection area; however, for strong, severe, and extreme MHWs, the mean projection area contributes much more than frequency. Due to the increased moving distance, the projected area change of the extreme MHW dominates the increase in the total projected area. The high sensitivity of extreme MHWs to global warming deserves extra attention. Plain Language Summary: Marine heatwaves (MHWs), which are characterized by temperatures exceeding a specific threshold for an extended period, have a severe impact on marine ecology and societal economics. Previous studies assumed that MHWs will become longer, more frequent, and more intense under global warming, but they ignored the movement of MHWs caused by ocean currents. Here, we use a three‐dimensional connected detection algorithm to track the spatiotemporal connection of MHWs across the globe over 1982–2020. The results show that global averages for MHW duration, intensity, area, and total distance have increased significantly except for MHW moving speed, frequency and area mean intensity. We find that stronger MHWs have a longer traveling distance and a larger affection area. As the total projection area is divided into the mean projection area and frequency, we further investigate the contribution of the frequency and mean projection area to the trend of the total projection area at different MHW intensities. We find that frequency contributes more to the increase in total projection area in weaker MHWs, while mean projection area contributes more in stronger MHWs. It is necessary to consider the movement of MHWs when predicting future changes in MHWs. Key Points: The frequency of MHWs showed an insignificant trend, and the duration, intensity, area and moving distance increased greatly over 1982–2020 The strongest MHWs (more than the 80th percentile) have the largest increase in moving distance The extreme MHW category dominates the increase in projection/total area due to the rising moving distance