The recent heatwave should remind us all that if it is hot on land, it is quite likely to be hot underwater. In fact, the current heatwave is causing some concern amongst marine scientists that the Great Barrier Reef may be facing a serious marine heatwave this summer.

Based on forecasts from the Bureau of Meteorology and the National Oceanic and Atmospheric Administration (NOAA), the Great Barrier Reef Marine Park Authority (GBRMPA) reports that the Reef will remain hotter than average across the Marine Park for the whole of January and into February, with bleaching expected at some scale during the summer months. This is despite having a well-established La Niña weather pattern which typically brings cooler conditions.

Unfortunately, as global warming heats up the oceans, a La Nina can no longer be counted on to the keep the ocean temperatures cool enough to prevent coral bleaching.

If bleaching occurs this year, the location and extent will, to a degree, be dependent on regional weather conditions, such as tropical storms and cyclones, over the next few weeks. In other words, it is time we all did a rain dance.

GBRMPA’s most recent report on 2022 summer conditions on the Reef:

Over the Christmas period, sea surface temperatures were generally up to 1.5°C above average for this time of year throughout most of the Marine Park. However, recent rainfall and cloud cover have resulted in some pockets of cooler water in the southernmost part of the Reef, with temperatures at or slightly below average.

 With higher-than-average sea surface temperatures since the start of December, the Marine Park has been accumulating thermal stress, which elevates the risk of coral bleaching.

 Bureau of Meteorology modelling indicates a high probability of sea surface temperatures exceeding the threshold for a marine heatwave in January.

Marine heatwaves often go unnoticed by the public because it is out of sight, but they can be quite destructive, causing mass coral bleaching which is nothing short of an underwater bush fire and can destroy vast swaths of coral. The Great Barrier Reef has suffered 3 mass bleaching events over the past 5 years and can ill afford another event this year.

Marine heat waves are driven by global warming which is fueled by the burning of fossil fuels such as coal. Scientists have made it very clear that we need to hold global warming to 1.5 degrees if the Reef is to have any chance of survival. Australia must step up its current climate policy. We must reduce our carbon emissions by 50% by 2030 and zero emissions by 2035.