Marine cold-spells

Schlegel, Robert W.; Darmaraki, Sofia; Benthuysen, Jessica A.; Filbee‐Dexter, Karen; Oliver, Eric C. J.

doi:10.1016/j.pocean.2021.102684

Cited by 65 publications

(99 citation statements)

References 130 publications

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“…MHWs are defined by temperature exceedances of the seasonally varying 90th percentile threshold, for at least 5 days, following the definition of Hobday et al (2016). MCSs are similarly defined, but instead for temperatures below the tenth percentile threshold (Schlegel et al, 2021). If two successive MHWs (or MCSs) occur with a gap of 2 days or less, they are regarded as a single continuous MHW (or MCS; Hobday et al [2016]; Schlegel et al [2017]).…”

Section: Defining Marine Cold-spells and Marine Heatwavesmentioning

confidence: 99%

“…MHWs have increased in frequency, duration, and intensity over the past century (Oliver et al., 2018), while MCSs have decreased in these metrics across most ocean surfaces (Schlegel et al., 2021). Hot spots for MHWs (Oliver et al., 2018) and cold spots for MCSs (Schlegel et al., 2021) have also been highlighted. These separate studies of MHWs and MCSs provide important estimates of global trends in these extremes.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the Changing Nature of Marine Cold‐Spells

Wang

Kajtar

Alexander

et al. 2022

Geophysical Research Letters

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Marine cold‐spell (MCS) metrics—such as frequency and intensity—are decreasing globally, while marine heatwave (MHW) metrics are increasing due to sea surface temperature (SST) warming. However, the concomitant changes in MHW and MCS metrics, and whether SST warming can similarly explain the decreasing MCS metrics remain unclear. Here, we provide a comparative global assessment of these changes based on satellite SST observations over 1982–2020. Across the globe, we find distinct differences in mean MHW and MCS metrics. Furthermore, decreasing trends in MCS metrics are not necessarily aligned with increasing trends in MHW metrics. While differences in intensity trends are mainly explained by SST variance trends, differences in trends of annual days are less clear. Overall, decreasing MCS days and intensities are found to be largely driven by warming SST, rather than SST variance changes. Therefore, it is expected that MCS days and intensity will continue diminishing under global warming.

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Section: Defining Marine Cold-spells and Marine Heatwavesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Understanding the Changing Nature of Marine Cold‐Spells

Wang

Kajtar

Alexander

et al. 2022

Geophysical Research Letters

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“…Marine temperature extreme events such as marine heatwaves (MHWs) and marine cold spells (MCSs) are periods of extremes (high and low, respectively) ocean temperatures that persist for days to months (Hobday et al, 2016;Schlegel et al, 2021). On average, over the satellite record, the frequency, intensity, duration, and spatial extent of MHWs have increased substantially globally (Frölicher et al, 2018;Oliver et al, 2018), while MCSs have decreased (Schlegel et al, 2017;Schlegel et al, 2021). Both MHWs and MCSs have pushed some marine organisms, fisheries and ecosystems beyond the limits of their resilience (MHWs: Smale et al, 2019;Oliver et al, 2021; MCSs: see review in Schlegel et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…On average, over the satellite record, the frequency, intensity, duration, and spatial extent of MHWs have increased substantially globally (Frölicher et al, 2018;Oliver et al, 2018), while MCSs have decreased (Schlegel et al, 2017;Schlegel et al, 2021). Both MHWs and MCSs have pushed some marine organisms, fisheries and ecosystems beyond the limits of their resilience (MHWs: Smale et al, 2019;Oliver et al, 2021; MCSs: see review in Schlegel et al, 2021). Marine temperature extreme events impact the ocean circulation and vertical turbulence with potential implications for deep nutrient upwelling and surface primary productivity (Auger et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Rohling et al (1998), by using paleorecords, suggest that cold air outbreaks led to abrupt MCSs in the western Mediterranean during Heinrich events. Schlegel et al (2021) were the first to quantify and report on MCS occurrence and trends in a global context. They show that the frequency and intensity declined globally over the last four decades, with no exception in the Mediterranean Sea.…”

Section: Introductionmentioning

confidence: 99%

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Hot and cold marine extreme events in the Mediterranean over the period 1982-2021

et al. 2022

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Marine temperature extremes are anomalous ocean temperature events, often persisting over several weeks or longer, with potential impacts on physical and ecological processes that often encompass socio-economic implications. In recent years, a considerable effort has been directed at the development of metrics allowing an objective characterization of both marine heatwaves (MHWs) and marine cold spells (MCSs). However, the majority of these metrics do not consider explicitly the spatial extent of the events. Here, we rank and evaluate the relative importance of marine temperature extreme events thanks to a metric, called activity, that combines the number of events, duration, intensity and spatial extent. According to this definition, in the Mediterranean basin between 1982 and 2021, summer 2018 experienced slightly more MHW activity than summer 2003, documented as an exceptional extreme event. Besides, MHW activities were higher in the last two decades while winter MCS activities were higher in the 1980s-1990s. The highest MHW activities occurred preferentially in the western Mediterranean while the strongest MCS activities took place preferentially in the eastern Mediterranean. Moreover, the duration, mean intensity, and activity of the three strongest MHWs are twice as high as those of the three strongest MCSs. The long-term tendency of extreme events activity shows an accelerated increase for summer MHWs (about +150°C.days.10⁶km²) and a linear decrease for winter MCSs in the Mediterranean (about -60°C.days.10⁶km²) over the last four decades.

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High survival following bleaching underscores the resilience of a frequently disturbed region of the Great Barrier Reef

et al. 2023

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Natural bleaching events provide an opportunity to examine how local‐scale environmental variation influences bleaching severity and recovery. During the 2020 marine heat wave, we documented widespread and severe coral bleaching affecting 75%–98% of coral cover throughout the Keppel Islands in the southern inshore Great Barrier Reef. Acropora, Pocillopora, and Porites were the most severely affected genera, while Montipora was comparatively less susceptible. Site‐specific heat‐exposure metrics were not correlated with Acropora bleaching severity, but recovery was faster at sites that experienced lower heat exposure. Despite severe bleaching and exposure to accumulated heat that often results in coral mortality (degree heating weeks ~4–8), cover remained stable. Approximately 94% of fate‐tracked Acropora millepora colonies survived, perhaps due to reduced irradiance stress from high turbidity, heterotrophic feeding, and large tidal flows that can increase mass transfer. Severe bleaching followed by rapid recovery and the continuing dominance of Acropora populations in the Keppel Islands is indicative of high resilience. These coral communities have survived a 0.8°C increase in average temperatures over the last 150 years. However, recovery following the 2020 bleaching was driven by the easing of thermal stress, which may challenge their recovery potential under further warming.

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Marine cold-spells

Cited by 65 publications

References 130 publications

Understanding the Changing Nature of Marine Cold‐Spells

Understanding the Changing Nature of Marine Cold‐Spells

Hot and cold marine extreme events in the Mediterranean over the period 1982-2021

High survival following bleaching underscores the resilience of a frequently disturbed region of the Great Barrier Reef

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