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Five years, three bleaching events. Troubled times for the Great Barrier Reef

April 28, 2020

By Dr Selina Ward, University of Queensland coral reef ecologist and Australian Marine Conservation Society board member.

With all that is changing in the world and our individual worlds shrinking momentously, I feel reluctant to discuss more bad news. But from the isolation of our homes or our distanced workplaces, the Great Barrier Reef is one of the places our day dreams will take us. It is somewhere we would rather be. Whether it’s a tent at Lady Musgrave Island, a hired yacht in the Whitsundays, my beloved Heron Island Research Station or a luxury resort at Lizard Island, the thoughts of visiting once this is all over will be a comfort for so many. The Great Barrier Reef belongs to all of us. We are all proud of it, we all deserve to know how it is faring and enjoy the hope that we will be able to save it, so forgive me for bringing more depressing news your way.

We are at present experiencing the second worst mass bleaching event yet on the reef – second only to 2016 and the third in five years. This is the most geographically widespread bleaching so far on the reef and it includes southern areas that have escaped the fury of the last two bleaching events. Each bleaching event is different with the highest mortality in different areas, but similar in that they all follow the temperature map of the sea with the areas of the highest accumulated heat the hardest hit. This year, the inshore reefs are suffering severe bleaching along the entire length of the Great Barrier Reef, with offshore reefs in the north and the south having relatively low levels of bleaching.

After the southern section was affected very little by bleaching in 2016 and 2017, some people have optimistically claimed that this area doesn’t bleach. Unfortunately, it has done in the past and was saved from the 2016 event by Cyclone Winston which devastated Fiji and sent a pool of cooler water to the southern GBR. It also suffered very little bleaching in 2017 but the south has not been so uniformly fortunate this year with bleaching recorded across many southern reefs.

Bleaching requires both elevated temperatures and bright sunlight, so we all hope for low pressure systems when the sea temperature increases. This is a fine line, as we don’t want a cyclone damaging reefs, but we want enough wind, clouds and rain to cut the light and reduce sea temperatures to stop bleaching in its tracks. This year we have had some low pressure systems during the accumulation of heat stress, so it is hoped that this will enhance the chances of recovery for the corals and reduce mortality rates, particularly in the vast areas that were moderately or mildly bleached.

We have known for decades that mass bleaching events are caused by elevated sea temperatures, and coral scientists have been warning governments what soaring emissions would do to reefs in the short and longer term. Now, more than two decades after Ove Hoegh-Guldberg’s paper explaining the increase in the frequency and severity of bleaching events that would occur with rising emissions, there is wide community acceptance of these facts. Unfortunately, there is not the consequent willingness of governments to put in place the changes we need to make to save the reef, no matter how much of it is lost, how many fires, intense cyclones or floods we have.  The answers are obvious and our governments cannot avoid being aware of the losses we are facing and the actions required to fix this.  However, the dramatic reductions in greenhouse gas emissions and the cessation of plans for new coal mines do not happen.

Perhaps one positive that may come from this terrible time is that the dramatic changes forced upon us through this pandemic may open our eyes to the fact that we can change things dramatically when we need to. We can recognise urgency when we have to. This is urgency for our reefs and so many other ecosystems. This is the time we have to act. We are running out of chances to be able to save these national treasures. Once we come out of this pandemic, with the great loss and hardship faced by our population, areas like the Great Barrier Reef will be vital for the healing process and the journey back to normal life. Please governments, take the chance now and be able to hold your heads high. Leave a legacy that won’t bring you shame.

This article was originally published in News Corp’s Rendezview column.