Global seasonal forecasts of marine heatwaves

Abstract

Marine heatwaves (MHWs)—periods of exceptionally warm ocean temperature lasting weeks to years—are now widely recognized for their capacity to disrupt marine ecosystems1–3. The substantial ecological and socioeconomic impacts of these extreme events present significant challenges to marine resource managers4–7, who would benefit from forewarning of MHWs to facilitate proactive decision-making8–11. However, despite extensive research into the physical drivers of MHWs11,12, there has been no comprehensive global assessment of our ability to predict these events. Here we use a large multimodel ensemble of global climate forecasts13,14 to develop and assess MHW forecasts that cover the world’s oceans with lead times of up to a year. Using 30 years of retrospective forecasts, we show that the onset, intensity and duration of MHWs are often predictable, with skilful forecasts possible from 1 to 12 months in advance depending on region, season and the state of large-scale climate modes, such as the El Niño/Southern Oscillation. We discuss considerations for setting decision thresholds based on the probability that a MHW will occur, empowering stakeholders to take appropriate actions based on their risk profile. These results highlight the potential for operational MHW forecasts, analogous to forecasts of extreme weather phenomena, to promote climate resilience in global marine ecosystems.

Global chlorophyll responses to marine heatwaves in satellite ocean color

“…Detection and attribution studies in current and future climates are needed to investigate how human activity influences MHW impacts phytoplankton dynamics under the expected more extreme events of future ocean environments (Frölicher et al 2018). With potential capabilities of MHWs prediction itself (Jacox et al 2022), the prediction of chlorophyll extreme responses to MHWs needs to be developed for providing the early warning forecasts in fisheries and establishing strategies in the global marine ecosystem managements.…”

The drivers and the implications of marine heatwaves

“…Or oyster farms could harvest earlier, before a heatwave killed their stock. Amaya’s latest research shows “significant prediction skill 6 to 8 months in advance,” he says ( 8 ).…”

Effects of Field Simulated Marine Heatwaves on Sedimentary Organic Matter Quantity, Biochemical Composition, and Degradation Rates

“…The consequences of oceans warming are multiple and affect both physical-chemical and biological features of the world's oceans [30,52]. Evidence that global warming is leading to progressively more frequent and intense MHWs is accumulating [4,12], along with proofs of MHW impacts on marine species, habitats, and communities [21,22,53,54]. Nonetheless, the effects of MHWs on sedimentary organic matter contents, composition and degradation rates are, to the best of our knowledge, so far to be assessed.…”

“…Over the last two decades, several MHWs have been recorded globally [3,7], including in the Mediterranean Sea [8][9][10]. Being a miniature, shallow and warm ocean more prone to climate change than the open oceans [11], the annual mean SST of the Mediterranean basin is expected to increase from +1.5 • C to +3 • C by the end of the 21st century, fostering MHWs' occurrence [9,12].…”