Unprecedented early-summer heat stress and forecast of coral bleaching on the Great Barrier Reef, 2021-2022

Blake L Spady; William J Skirving; Gang Liu; Jacqueline L De La Cour; Cathy J McDonald; Derek P Manzello

doi:10.12688/f1000research.108724.4

Unprecedented early-summer heat stress and forecast of coral bleaching on the Great Barrier Reef, 2021-2022

F1000Res. 2022 Feb 1:11:127. doi: 10.12688/f1000research.108724.4. eCollection 2022.

Authors

Blake L Spady^{1

2}, William J Skirving^{1

2}, Gang Liu^{1

3}, Jacqueline L De La Cour^{1

3}, Cathy J McDonald², Derek P Manzello¹

Affiliations

¹ Center for Satellite Applications and Research, Satellite Oceanography and Climate Division, U.S. National Oceanic and Atmospheric Administration, College Park, Maryland, 20740, USA.
² ReefSense Pty, Ltd., P.O. Box 343, Aitkenvale, Queensland, 4814, Australia.
³ Earth System Science Interdisciplinary Center, Cooperative Institute for Satellite Earth System Studies, University of Maryland, College Park, Maryland, 20740, USA.

Abstract

The Great Barrier Reef (GBR) is predicted to undergo its sixth mass coral bleaching event during the Southern Hemisphere summer of 2021-2022. Coral bleaching-level heat stress over the GBR is forecast to start earlier than any previous year in the satellite record (1985-present). The National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch (CRW) near real-time satellite-based heat stress products were used to investigate early-summer sea surface temperature (SST) and heat stress conditions on the GBR during late 2021. As of 14 December 2021, values of instantaneous heat stress (Coral Bleaching HotSpots) and accumulated heat stress over a 12-week running window (Degree Heating Weeks) on the GBR were unprecedented in the satellite record. Further, 89% of GBR satellite reef pixels for this date in 2021 had a positive seven-day SST trend of greater than 0.2 degrees Celsius/week. Background temperatures (the minimum temperature over the previous 29 days) were alarmingly high, with 87% of GBR reef pixels on 14 December 2021 being greater than the maximum SST over that same 29-day period for any year from 1985-2020. The GBR is starting the 2021-2022 summer season with more accumulated heat than ever before, which could have disastrous consequences for the health, recovery, and future of this critical reef system.

Keywords: Background temperature; Bleaching; Coral; Degree Heating Week; Great Barrier Reef; La Niña; heat stress; satellite monitoring.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Heat-Shock Response*

Grants and funding

The National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch (CRW) program was supported by funding from the NOAA Coral Reef Conservation Program. NOAA CRW and ReefSense staff were fully supported by the NOAA grant NA19NES4320002 (Cooperative Institute for Satellite Earth System Studies) at the University of Maryland/Earth System Science Interdisciplinary Center.