DOCSLIB.ORG

Physical Drivers of the Summer 2019 North Pacific Marine Heatwave

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Physical Drivers of the Summer 2019 North Pacific Marine Heatwave UC San Diego UC San Diego Previously Published Works Title Physical drivers of the summer 2019 North Pacific marine heatwave. Permalink https://escholarship.org/uc/item/2jm2n24t Journal Nature communications, 11(1) ISSN 2041-1723 Authors Amaya, Dillon J Miller, Arthur J Xie, Shang-Ping et al. Publication Date 2020-04-20 DOI 10.1038/s41467-020-15820-w Peer reviewed eScholarship.org Powered by the California Digital Library University of California ARTICLE https://doi.org/10.1038/s41467-020-15820-w OPEN Physical drivers of the summer 2019 North Pacific marine heatwave ✉ Dillon J. Amaya 1,2 , Arthur J. Miller3, Shang-Ping Xie 3 & Yu Kosaka 4 Summer 2019 observations show a rapid resurgence of the Blob-like warm sea surface temperature (SST) anomalies that produced devastating marine impacts in the Northeast Pacific during winter 2013/2014. Unlike the original Blob, Blob 2.0 peaked in the summer, a 1234567890():,; season when little is known about the physical drivers of such events. We show that Blob 2.0 primarily results from a prolonged weakening of the North Pacific High-Pressure System. This reduces surface winds and decreases evaporative cooling and wind-driven upper ocean mixing. Warmer ocean conditions then reduce low-cloud fraction, reinforcing the marine heatwave through a positive low-cloud feedback. Using an atmospheric model forced with observed SSTs, we also find that remote SST forcing from the central equatorial and, sur- prisingly, the subtropical North Pacific Ocean contribute to the weakened North Pacific High. Our multi-faceted analysis sheds light on the physical drivers governing the intensity and longevity of summertime North Pacific marine heatwaves. 1 Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, USA. 2 Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, CO, USA. 3 Scripps Institution of Oceanography, University of California San Diego, San Diego, CA, USA. ✉ 4 Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan. email: [email protected] NATURE COMMUNICATIONS | (2020) 11:1903 | https://doi.org/10.1038/s41467-020-15820-w | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-020-15820-w n winter 2013/2014 upper ocean temperatures in the North- the winter and was the result of a resilient atmospheric ridge in Ieast Pacific were remarkably warm over a large area, with peak the Northeast Pacific, which weakened the climatological Aleu- values near 2.5 °C or three standard deviations above normal. tian Low and related surface winds. The reduced wind forcing The extraordinary magnitude and persistence of these anomalies decreased Ekman advection of cold water from higher latitudes posed a significant threat to regional marine ecosystems1, earning and reduced wind-generated upper ocean mixing, which allowed this pattern the moniker The Blob in the scientific literature and surface heat fluxes to significantly warm the upper ocean2. media2. Over the subsequent months, The Blob anomalies spread While stalled atmospheric high-pressure systems have been along the western North American coastline as the result of linked to the development of other wintertime marine heat- shifting atmospheric forcing, generating significant coastal waves10, it is not clear that this is a viable forcing mechanism in warming and unprecedented marine impacts during the summer the summer when the mean circulation itself is dominated by a of 2014 and into winter 2014/20153–5. As a result, the 2013–2015 ridge—the North Pacific High. For example, an anomalous North Pacific warm anomalies have since generated significant summertime atmospheric ridge would tend to strengthen the scientific interest into the origin, persistence, probability, and background mean circulation (i.e., the surface westerlies) when intensification of so-called marine heatwaves4–10. superposed on the climatological North Pacific High. This would Half a decade later, upper ocean temperatures near the Gulf of increase surface evaporation and wind-generated upper ocean Alaska have risen to unprecedented levels (Fig. 1), leading to mixing. As a result, we might actually expect a series of anom- significant public concern that The Blob and its devastating alous summertime ridging events to cool the Northeast impacts have once again returned. However, an important dis- Pacific Ocean. tinction between the recent temperature anomalies (hereafter In addition, studies have shown that the remarkable persistence referred to as Blob 2.0) and 2013/2014 temperature anomalies of the winter 2013/2014 Northeast Pacific ridge was partly the (hereafter referred to as Blob 1.0) is that Blob 2.0 has primarily result of remote sea surface temperature (SST) forcing through intensified during the summer season. The Blob 1.0 originated in atmospheric teleconnections4,8,11,12. There has been considerable research on SST-forced teleconnections to the North Pacific during boreal winter when important climate modes like the El a 60 Niño Southern Oscillation (ENSO) tend to peak13,14, but there has been comparably less work on the influence of remote SST on North Pacific ocean-atmospheric variability during the summer15,16. Further, while local air–sea feedbacks were not 50 thought to be an important sustaining mechanism for Blob 1.0, they may be a significant driver of the Blob 2.0 due to the per- vasiveness of marine stratocumulus clouds during boreal sum- mer. An analysis of the physical mechanisms behind Blob 2.0 and 40 the extent to which remote and/or local SST forcing may be playing a role would improve our understanding of the devel- opment, evolution, and persistence of summertime marine 30 heatwaves in this region. In this study, we use gridded reanalysis products combined with satellite-derived observations to investigate the physical drivers that led to the rapid intensification of the summer 2019 20 Northeast Pacific SST anomalies. We find that Blob 2.0 primarily 180 195 210 225 240 results from an anomalous weakening of the North Pacific High, which significantly reduces wind-driven upper ocean mixing, –2.5 –2 –1.5 –1 –0.5 0 0.5 1 1.5 2 2.5 producing a record shallow mixed layer depth. As a result, strong °C downward surface heat fluxes mixed over an anomalously thin mixed layer volume, resulting in record warming for this region. b We then use a suite of SST-forced atmospheric model simulations 3 to conduct a near real-time attribution analysis of the North Pacific atmospheric circulation anomalies. We show that, while 2 the magnitude of North Pacific High weakening primarily results from internal atmospheric variability, the circulation anomalies 1 are reinforced in time and space by atmospheric teleconnections SSTA 0 originating from both the tropics and, surprisingly, the sub- tropical North Pacific. In addition, we present satellite and model –1 evidence that surface warming associated with Blob 2.0 sig- –2 nificantly reduce low-cloud fraction in the North Pacific, sug- – 1980 1985 1990 1995 2000 2005 2010 2015 gesting an important role for local air sea feedbacks in amplifying/sustaining the summer 2019 marine heatwave. Year Fig. 1 The Blob 2.0 in an ocean reanalysis product. a Five-meter ocean temperature anomalies (°C) averaged for June–August (JJA) 2019 in Results Global Ocean Data Assimilation System (GODAS). b Time series of Drivers of Blob 2.0 in observational analyses. To investigate the normalized monthly mean sea surface temperature anomalies area- driving mechanisms behind Blob 2.0, we begin by inspecting weighted averaged in black box above, smoothed with a 3-month running June–August (JJA) 2019 averaged SSTAs in the North Pacific mean for the period 1980–2019. Red dot marks JJA 2019. Green dots mark (Fig. 1a). Similar to 2013/2014, ocean reanalysis data sets show a the two peaks of Blob 1.0 averaged in January–March 2014 and May–July Blob of anomalous ocean warming off the United States west 2015, respectively. coast, with a peak magnitude of over 2.5 °C at the center 2 NATURE COMMUNICATIONS | (2020) 11:1903 | https://doi.org/10.1038/s41467-020-15820-w | www.nature.com/naturecommunications NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-020-15820-w ARTICLE a 60 a 15 1008 10 40 1016 1024 1020 1008 5 20 1012 0 Heat budget (°C) 0 1012 Δ –5 T Qnet Advection 120 180 240 300 Residual –5 –4 –3 –2 –1 0 1 2 3 4 5 b 525 30 hPa ) –3 Mixed layer depth (m) s 3 450 25 b –3 3 –2 2 375 20 –1 1 SSTA 0 0 300 15 1 –1 Wind speed cubed (m 225 10 N. Pac. High Intensity Pac. N. 2 –2 1980 1985 1990 1995 2000 2005 2010 2015 3 –3 Fig. 3 Mixed layer heat budget estimated in ocean reanalysis. a August 1980 1985 1990 1995 2000 2005 2010 2015 minus May temperature change (°C; blue) and the respective budget terms Fig. 2 Atmospheric circulation anomalies during summer 2019. a contributing to this change. Budget terms include total surface heat flux Detrended sea level pressure anomalies (SLPAs; hPa; shading) from (red), horizontal advection (brown), and entrainment/residual (gray). atmospheric reanalysis averaged June–August (JJA) 2019 (shading and thin b June–August (JJA)-averaged reanalysis wind speed cubed (green/left y- − contours). Heavy dark contours represent JJA SLP climatology. Red axis; m3 s 3) and mixed layer depth (purple/right y-axis; m) area-weighted contours are sea surface temperature anomalies (SSTAs) from Fig. 1a averaged in black box seen in Fig. 1a. All time series are for the time period (starting at 1 °C with 0.5 °C interval). Black box represents area of 1980–2019. comparison for Best Member results in Fig. 5d–f. b Time series of the North Pacific High Intensity index (gray/left y-axis; hPa; negative = weaker; see “Methods”) and normalized JJA SSTA area-weighted averaged in the black detrended, both 95% significant) suggests that a weakened mean box shown in Fig.
Load more

Recommended publications
  • Emerging Risks from Marine Heat Waves
    COMMENT DOI: 10.1038/s41467-018-03163-6 OPEN Emerging risks from marine heat waves Thomas L. Frölicher1,2 & Charlotte Laufkötter 1,2 Recent marine heat waves have caused devastating impacts on marine ecosystems. Sub- stantial progress in understanding past and future changes in marine heat waves and their risks for marine ecosystems is needed to predict how marine systems, and the goods and 1234567890():,; services they provide, will evolve in the future. Extreme climate and weather events shape the structure of terrestrial biological systems and affect the biogeochemical functions and services they provide for society in a fundamental manner1. There is overwhelming evidence that atmospheric heat waves over land are changing under global warming, increasing the risk of severe, pervasive and in some cases irreversible impacts on natural and socio-economic systems2. In contrast, we know little how extreme events in the ocean, especially those associated with warming will change under global warming, and how they will impact marine organisms. This knowledge gap is of particular concern as some of the recent observed marine heat waves (MHWs) demonstrated the high vulnerability of marine organisms and ecosystems services to such extreme climate events. Definition, observations, and key processes A marine heat wave is usually defined as a coherent area of extreme warm sea surface tem- perature (SST) that persists for days to months3. MHWs have been observed in all major ocean basins over the recent decade, but only a few MHWs have been documented and analyzed extensively (Fig. 1). One of the first MHW that has been characterized in the literature occurred in 2003 in the northwestern Mediterranean Sea with SSTs reaching 3–5 °C above the 1982–2016 reference period4.
    [Show full text]
  • Seagrass Recovery Following Marine Heat Wave Influences Sediment Carbon Stocks
    W&M ScholarWorks VIMS Articles Virginia Institute of Marine Science 1-2021 Seagrass Recovery Following Marine Heat Wave Influences Sediment Carbon Stocks Lillian R. Aoki Karen J. McGlathery Patricia L. Wiberg Matthew P. J. Oreska Amelie C. Berger See next page for additional authors Follow this and additional works at: https://scholarworks.wm.edu/vimsarticles Part of the Marine Biology Commons Recommended Citation Aoki, Lillian R.; McGlathery, Karen J.; Wiberg, Patricia L.; Oreska, Matthew P. J.; Berger, Amelie C.; Berg, Peter; and Orth, Robert J., Seagrass Recovery Following Marine Heat Wave Influences Sediment Carbon Stocks (2021). Frontiers in Marine Science, 7, 576784.. doi: 10.3389/fmars.2020.576784 This Article is brought to you for free and open access by the Virginia Institute of Marine Science at W&M ScholarWorks. It has been accepted for inclusion in VIMS Articles by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. Authors Lillian R. Aoki, Karen J. McGlathery, Patricia L. Wiberg, Matthew P. J. Oreska, Amelie C. Berger, Peter Berg, and Robert J. Orth This article is available at W&M ScholarWorks: https://scholarworks.wm.edu/vimsarticles/2036 fmars-07-576784 December 23, 2020 Time: 12:35 # 1 ORIGINAL RESEARCH published: 07 January 2021 doi: 10.3389/fmars.2020.576784 Seagrass Recovery Following Marine Heat Wave Influences Sediment Carbon Stocks Lillian R. Aoki1*†, Karen J. McGlathery1, Patricia L. Wiberg1, Matthew P. J. Oreska1, Amelie C. Berger1, Peter Berg1 and Robert J. Orth2 1 Department of Environmental Sciences, University of Virginia, Charlottesville, VA, United States, 2 Virginia Institute of Marine Science, William and Mary, Gloucester Point, VA, United States Worldwide, seagrass meadows accumulate significant stocks of organic carbon (C), known as “blue” carbon, which can remain buried for decades to centuries.
    [Show full text]
  • The Tale of a Surprisingly Cold Blob in the North Atlantic
    VARIATIONSUS CLIVAR VARIATIONS CUS CLIVAR lim ity a bil te V cta ariability & Predi Spring 2016 • Vol. 14, No. 2 A Tale of Two Blobs The evolution and known atmospheric Editors: forcing mechanisms behind the 2013-2015 Kristan Uhlenbrock & Mike Patterson North Pacific warm anomalies From 2013 to 2015, the scientific 1 2 community and the media were Dillon J. Amaya Nicholas E. Bond , enthralled with two anomalous Arthur J. Miller1, and Michael J. DeFlorio3 sea surface temperature events, both getting the moniker 1Scripps Institution of Oceanography the “Blob,” although one was 2 warm and one was cold. These University of Washington 3 events occurred during a Jet Propulsion Laboratory, California Institute of Technology period of record-setting global mean surface temperatures. This edition focuses on the timing and extent, possible mechanisms, and impacts ear-to-year variations in the El Niño Southern Oscillation (ENSO) indices of these unusual ocean heat Ygenerate significant interest throughout the general public and the scientific anomalies, and what we might community due to the sometimes destructive nature of this climate mode. For expect in the future as climate example, so-called “Godzilla” ENSOs can generate billions of dollars in damages changes. from the US agricultural industry alone due to unanticipated flooding or drought The “Warm Blob” feature (Adams et al. 1999). However, in the winter of 2013/2014, North Pacific sea surface appeared in the North Pacific temperature (SST) anomalies exceeded three standard deviations above the mean during winter 2013 and was over a large region, shifting focus away from the tropics and onto the extratropics first identified by Nick Bond, as the associated atmospheric circulation patterns helped exacerbate the most University of Washington.
    [Show full text]
  • STATE of the CALIFORNIA CURRENT 2018–19: a NOVEL ANCHOVY REGIME and a NEW MARINE HEATWAVE? Calcofi Rep., Vol
    STATE OF THE CALIFORNIA CURRENT 2018–19: A NOVEL ANCHOVY REGIME AND A NEW MARINE HEATWAVE? CalCOFI Rep., Vol. 60, 2019 STATE OF THE CALIFORNIA CURRENT 2018–19: A NOVEL ANCHOVY REGIME AND A NEW MARINE HEAT WAVE? ANDREW R. THOMPSON* MATI KAHRU EDWARD D. WEBER National Marine Fisheries Service AND RALF GOERICKE AND WILLIAM WATSON Southwest Fisheries Science Center Scripps Institution of Oceanography National Marine Fisheries Service 8901 La Jolla Shores Drive University of California, San Diego Southwest Fisheries Science Center La Jolla, CA, 92037-1509 La Jolla, CA 92093 8901 La Jolla Shores Drive [email protected] La Jolla, CA 92037-1509 CLARE E. PEABODY ISAAC D. SCHROEDER1,2, National Marine Fisheries Service JESSICA M. PORQUEZ1, STEVEN J. BOGRAD1, ELLIOTT L. HAZEN1, Southwest Fisheries Science Center JANE DOLLIVER1, MICHAEL G. JACOX1,3, ANDREW LEISING1, 8901 La Jolla Shores Drive DONALD E. LYONS1,2, AND AND BRIAN K. WELLS4 La Jolla, CA 92037-1509 RACHAEL A. ORBEN1 1Southwest Fisheries Science Center 1Department of Fisheries and Wildlife National Marine Fisheries Service TIMOTHY R. BAUMGARTNER, Oregon State University 99 Pacific Street, Suite 255A BERTHA E. LAVANIEGOS, Hatfield Marine Science Center Monterey, CA 93940-7200 LUIS E. MIRANDA, Newport, OR 97365 ELIANA GOMEZ-OCAMPO, 2Institute of Marine Sciences 2National Audubon Society University of California AND JOSE GOMEZ-VALDES 104 Nash Hall Santa Cruz, CA Oceanology Division Corvallis, OR 97331 and Centro de Investigación Científica y Southwest Fisheries Science Center Educación Superior de Ensenada JEANNETTE E. ZAMON NOAA Carretera Ensenada-Tijuana No. 3918 Northwest Fisheries Science Center Monterey, CA Zona Playitas C.P.
    [Show full text]
  • A Marine Heatwave Drives Massive Losses from the World's Largest Seagrass Carbon Stocks
    A marine heatwave drives massive losses from the world’s largest seagrass carbon stocks Item Type Article Authors Arias-Ortiz, Ariane; Serrano, Oscar; Masqué, Pere; Lavery, P. S.; Mueller, U.; Kendrick, G. A.; Rozaimi, M.; Esteban, A.; Fourqurean, J. W.; Marbà, N.; Mateo, M. A.; Murray, K.; Rule, M. J.; Duarte, Carlos M. Citation Arias-Ortiz A, Serrano O, Masqué P, Lavery PS, Mueller U, et al. (2018) A marine heatwave drives massive losses from the world’s largest seagrass carbon stocks. Nature Climate Change 8: 338– 344. Available: http://dx.doi.org/10.1038/s41558-018-0096-y. Eprint version Post-print DOI 10.1038/s41558-018-0096-y Publisher Springer Nature Journal Nature Climate Change Rights The final publication is available at Springer via http:// dx.doi.org/10.1038/s41558-018-0096-y Download date 15/02/2020 20:13:16 Link to Item http://hdl.handle.net/10754/627404 ARTICLES https://doi.org/10.1038/s41558-018-0096-y A marine heatwave drives massive losses from the world’s largest seagrass carbon stocks A. Arias-Ortiz 1*, O. Serrano 2,3, P. Masqué 1,2,3, P. S. Lavery2,4, U. Mueller2, G. A. Kendrick 3,5, M. Rozaimi 2,6, A. Esteban2, J. W. Fourqurean 5,7, N. Marbà8, M. A. Mateo2,4, K. Murray9, M. J. Rule3,9 and C. M. Duarte8,10 Seagrass ecosystems contain globally significant organic carbon (C) stocks. However, climate change and increasing frequency of extreme events threaten their preservation. Shark Bay, Western Australia, has the largest C stock reported for a seagrass ecosystem, containing up to 1.3% of the total C stored within the top metre of seagrass sediments worldwide.
    [Show full text]
  • Changes in Rocky Intertidal Community Structure During a Marine Heatwave in the Northern Gulf of Alaska
    fmars-08-556820 February 15, 2021 Time: 11:21 # 1 ORIGINAL RESEARCH published: 17 February 2021 doi: 10.3389/fmars.2021.556820 Changes in Rocky Intertidal Community Structure During a Marine Heatwave in the Northern Gulf of Alaska Benjamin Weitzman1,2*, Brenda Konar2, Katrin Iken2, Heather Coletti3, Daniel Monson4, Robert Suryan5, Thomas Dean6, Dominic Hondolero1 and Mandy Lindeberg5 1 Kasitsna Bay Laboratory, National Centers for Coastal Ocean Sciences, National Ocean Service, National Oceanic and Atmospheric Administration, Homer, AK, United States, 2 College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, United States, 3 Southwest Alaska Network, Inventory & Monitoring Program, National Park Service, Fairbanks, AK, United States, 4 Alaska Science Center, U.S. Geological Survey, Anchorage, AK, United States, 5 Auke Bay Laboratories, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Juneau, AK, United States, 6 Coastal Resources Associates, Carlsbad, CA, United States Edited by: Marine heatwaves are global phenomena that can have major impacts on the structure Christos Dimitrios Arvanitidis, Hellenic Centre for Marine Research and function of coastal ecosystems. By mid-2014, the Pacific Marine Heatwave (HCMR), Greece (PMH) was evident in intertidal waters of the northern Gulf of Alaska and persisted Reviewed by: for multiple years. While offshore marine ecosystems are known to respond to Francisco Arenas, University of Porto, Portugal these warmer waters, the response of rocky intertidal ecosystems to this warming Rodrigo Riera, is unclear. Intertidal communities link terrestrial and marine ecosystems and their University of Las Palmas de Gran resources are important to marine and terrestrial predators and to human communities Canaria, Spain for food and recreation, while simultaneously supporting a growing coastal tourism *Correspondence: Benjamin Weitzman industry.
    [Show full text]
  • Climate Change Impacts on the Great Barrier Reef
    UPDATE 2018 LETHAL CONSEQUENCES: CLIMATE CHANGE IMPACTS ON THE GREAT BARRIER REEF CLIMATECOUNCIL.ORG.AU Thank you for supporting the Climate Council. The Climate Council is an independent, crowd-funded organisation providing quality information on climate change to the Australian public. Published by the Climate Council of Australia Limited ISBN: 978-1-925573-62-6 (print) 978-1-925573-63-3 (digital) © Climate Council of Australia Ltd 2018 Professor Lesley Hughes Climate Councillor This work is copyright the Climate Council of Australia Ltd. All material contained in this work is copyright the Climate Council of Australia Ltd except where a third party source is indicated. Climate Council of Australia Ltd copyright material is licensed under the Creative Commons Attribution 3.0 Australia License. To view a copy of this license visit http://creativecommons.org.au. You are free to copy, communicate and adapt the Climate Council of Australia Ltd copyright material so long as you attribute the Climate Dr Annika Dean Council of Australia Ltd and the authors in the following manner: Senior Researcher Lethal Consequences: Climate Change Impacts on the Great Barrier Reef. Authors: Lesley Hughes, Annika Dean, Will Steffen and Martin Rice. — Cover photo: ‘Graveyard of Staghorn coral, Yonge reef, Northern Great Professor Will Steffen Barrier Reef, October 2016’ by Greg Torda ARC Centre of Excellence for Coral Reef Studies (CC BY-ND 2.0). Climate Councillor This report is printed on 100% recycled paper. facebook.com/climatecouncil [email protected] twitter.com/climatecouncil climatecouncil.org.au Dr Martin Rice Head of Research Preface In 2016 and 2017 the Great Barrier Reef experienced unprecedented back-to-back mass bleaching events, driven by marine heatwaves.
    [Show full text]
  • Understanding Physical Drivers of the 2015/16 Marine Heatwaves in the Northwest Atlantic E
    www.nature.com/scientificreports OPEN Understanding physical drivers of the 2015/16 marine heatwaves in the Northwest Atlantic E. Perez1*, S. Ryan1, M. Andres1, G. Gawarkiewicz1, C. C. Ummenhofer1, J. Bane2 & S. Haines2 The Northwest Atlantic, which has exhibited evidence of accelerated warming compared to the global ocean, also experienced several notable marine heatwaves (MHWs) over the last decade. We analyze spatiotemporal patterns of surface and subsurface temperature structure across the Northwest Atlantic continental shelf and slope to assess the infuences of atmospheric and oceanic processes on ocean temperatures. Here we focus on MHWs from 2015/16 and examine their physical drivers using observational and reanalysis products. We fnd that a combination of jet stream latitudinal position and ocean advection, mainly due to warm core rings shed by the Gulf Stream, plays a role in MHW development. While both atmospheric and oceanic drivers can lead to MHWs they have diferent temperature signatures with each afecting the vertical structure diferently and horizontal spatial patterns of a MHW. Northwest Atlantic MHWs have signifcant socio-economic impacts and afect commercially important species such as squid and lobster. Marine heatwaves (MHWs), defned as discrete events of anomalously warm ocean temperatures, can disrupt marine ecosystems and hence human industries like fsheries, tourism, and aquaculture. MHWs can occur throughout the global ocean and across seasons. Under anthropogenic climate change, more intense and frequent MHWs are expected1,2. Te Northwest Atlantic (NWA, see Fig. 1), where waters are warming four times faster than the global average, has experienced notable MHWs in the last decade 3–6. Tis region is home to a highly productive ecosystem with signifcant economic importance, and includes the highest-valued seafood port in the United States, located in New Bedford, MA 7.
    [Show full text]
  • Marine Heatwave Drives Collapse of Kelp Forests in Western Australia
    Marine heatwave drives collapse of kelp forests in Western Australia Thomas Wernberg UWA Oceans Institute & School of Biological Sciences The University of Western Australia Correspondence: [email protected] Abstract Marine heatwaves (MHWs) are discrete, unusually warm water events which can have devastating ecological impacts. In 2011, Western Australia experienced an extreme MHW, affecting >2,000 km of coastline for >10 weeks. During the MHW temperatures exceeded the physiological threshold for net growth (~23 °C) for kelp (Ecklonia radiata) along large tracts of coastline. Kelp went locally extinct across 100 km of its northern (warm) distribution. In total, an estimated 43% of the kelp along the west coast perished, and widespread shifts in species distributions were seen across seaweeds, invertebrates and fish. With the loss of kelp, turf algae expanded rapidly and now cover many reefs previously dominated by kelp. The changes in ecosystem structure led to blocking of kelp recruitment by expansive turfs and elevated herbivory from increased populations of warm-water fishes - feedback processes that prevent the recovery of kelp forests. Water temperature has long returned to pre- MHW levels, yet today, eight years after the event, the kelp forests have not recovered. This supports initial concerns that the transformation to turf reefs represents a persistent change to a turf- dominated state. MHWs are a manifestation of ocean warming; they are being recorded with increasing frequency in all oceans, and these extreme events are set to shape our future marine ecosystems. Full citation: Wernberg T (2020) Marine heatwave drives collapse of kelp forests in Western Australia. In: Canadell JG, Jackson RB (eds) Ecosystem Collapse and Climate Change.
    [Show full text]
  • Status of Bleaching Heat Stress on the Great Barrier Reef, Australia – 2020
    Status of Bleaching Heat Stress on the Great Barrier Reef, Australia – 2020 Update: April 16, 2020 (End of Event Summary) By: Dr. William Skirving (NOAA Coral Reef Watch Senior Scientist) At last it is safe to say that the 2020 heat stress event for the Great Barrier Reef (GBR) in Australia is over. The task of assessing the extent and severity of the marine heatwave and its impacts on coral reefs is still underway. NOAA Coral Reef Watch’s (CRW) Four-Month Coral Bleaching Outlook product performed extremely well throughout this event. It gave an extremely accurate prediction of the heat stress event weeks in advance of the stress actually occurring. It also managed to accurately predict the timing of the end of the event. The most alarming aspect of this event is that it was the most widespread heat stress event on the GBR (during the satellite era), and yet this year was ENSO (El Niño Southern Oscillation) neutral, which means that there was no tropical climate forcing being applied to the region from ENSO. It begs the question of how much worse it might have been, were an El Niño present. CRW’s daily global 5km satellite coral bleaching Degree Heating Week (DHW) of March 30, 2020 is pictured below (Figure 1). This image represents the total accumulated heat stress for the GBR for the 2020 event. Figure 1. NOAA CRW’s daily global 5km satellite coral bleaching DHW product for the GBR on March 30, 2020. 1 When interpreting Figure 1, it’s important to note that based on CRW’s recent analysis of past bleaching events along the GBR, combined with in-water reports of bleaching received from the Great Barrier Reef Marine Park Authority (GBRMPA), Australian Institute of Marine Science (AIMS), and the University of Queensland (UQ), we expect that a DHW value of 2.5 °C-weeks is a relatively conservative threshold for mapping significant coral bleaching along the reef tract during this event.
    [Show full text]
  • El Niño Southern Oscillation (ENSO) Effects on Fisheries and Aquaculture
    ISSN 2070-7010 FAO 660 FISHERIES AND AQUACULTURE TECHNICAL PAPER 660 El Niño Southern Oscillation (ENSO) effects on fisheries and aquaculture El Niño Southern Oscillation (ENSO) effects on fisheries and aquaculture This FAO Technical Paper synthesizes current knowledge on the impact of El Niño Southern Oscillation (ENSO) events on fisheries and aquaculture in the context of a changing climate. Fisheries and aquaculture are essential parts of the global food system. The recent discovery that ENSO is far more diverse than previously recognized highlights a pressing need to synthesize the impact of the different ENSO types on fisheries and aquaculture. The overall aim of this Technical Paper is to provide relevant, up-to-date information and help decision-makers identify the most appropriate interventions according to the diversity of ENSO types. In addition, the possible effects of climate change on these sectors can be partly illustrated by the current effects of ENSO events, which are themselves affected by climate change. The Technical Paper describes the diversity of ENSO events (Chapter 2), ENSO forecasting (Chapter 3) and ENSO in the context of climate change (Chapter 4). It includes a global overview and regional assessment of ENSO impact (Chapters 5 and 6) and a focus on coral bleaching and damage to reefs and related fisheries (Chapter 7). Finally, it synthesizes the lessons learned and the perspectives for ENSO and preparedness in a warmer ocean (Chapter 10). ISBN 978-92-5-132327-4 ISSN 2070-7010 F Institut de Recherche AO 9 789251
    [Show full text]
  • Widespread Shifts in the Coastal Biota of Northern California During the 2014–2016 Marine Heatwaves Received: 22 October 2018 Eric Sanford1,2, Jacqueline L
    www.nature.com/scientificreports OPEN Widespread shifts in the coastal biota of northern California during the 2014–2016 marine heatwaves Received: 22 October 2018 Eric Sanford1,2, Jacqueline L. Sones3, Marisol García-Reyes4, Jefrey H. R. Goddard5 Accepted: 19 February 2019 & John L. Largier1,6 Published: xx xx xxxx During 2014–2016, severe marine heatwaves in the northeast Pacifc triggered well-documented disturbances including mass mortalities, harmful algal blooms, and declines in subtidal kelp beds. However, less attention has been directed towards understanding how changes in sea surface temperature (SST) and alongshore currents during this period infuenced the geographic distribution of coastal taxa. Here, we examine these efects in northern California, USA, with a focus on the region between Point Reyes and Point Arena. This region represents an important biogeographic transition zone that lies <150 km north of Monterey Bay, California, where numerous southern species have historically reached their northern (poleward) range limits. We report substantial changes in geographic distributions and/or abundances across a diverse suite of 67 southern species, including an unprecedented number of poleward range extensions (37) and striking increases in the recruitment of owl limpets (Lottia gigantea) and volcano barnacles (Tetraclita rubescens). These ecological responses likely arose through the combined efects of extreme SST, periods of anomalous poleward fow, and the unusually long duration of heatwave events. Prolonged marine heatwaves and enhanced poleward dispersal may play an important role in longer-term shifts in the composition of coastal communities in northern California and other biogeographic transition zones. Marine heatwaves are defined as periods of extreme sea surface temperature (SST) persisting for days to months1,2.
    [Show full text]