A marine heatwave has broken out along more than 2,000km of the Queensland coast, raising concerns for the health of corals on the Great Barrier Reef and other ocean life.
The Bureau of Meteorology briefed the Great Barrier Reef Marine Park Authority about the raised ocean temperatures on Friday.
A marine heatwave happens when temperatures over an area are in the hottest 10% ever recorded for that time of year and then stay there for at least five days.
Dr Alex Sen Gupta, an associate professor at the UNSW Climate Change Research Centre and marine heatwave expert, said: "If you look globally, we’re seeing more marine heatwaves now than we have ever seen before."It’s exceptional at the moment.
Dr Jessica Stella, the assistant director of reef health at GBRMPA, said there was still an element of the unknown about the effects of a heatwave in winter, when overall temperatures are cooler than in the summer.
It’s… not fun.
I’ve spent a little time around the Keppels. I remember kayaking out to Humpy island in August 2010, and being astounded by the vivid blue staghorn coral at the reef edge.
I’ve been back many times since, and though the coral health surges and wanes, the general trend is definitely negative. There are still small hints of colour in the reef around Humpy, but white, and white with hints of brown, predominates. In the last year or so I’ve started to see a few deeper water corals start to regenerate a little, and some of the more distant bays seem to be surging a little - but they’re fighting a losing battle.
We’re seeing less of this.
… and more of this.
… and fair enough, that second shot shows indications of damage unrelated to heat (maybe a boat anchor perhaps?) - but it’s indicative. For better or worse, heat means that coral resilience drops through the floor. Anchor damage, tsunami, cyclone, crown-of-thorns. Things that it used to be able to shrug off in a reasonable timeframe, now cause long term issues.