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Queensland’s Great Barrier Reef is staring at the barrel of another tough summer as this year’s La Nina weather increases the risk of damage from extreme weather events.
La Nina is likely to bring more tropical cyclones, rains and floods than average over the next four months, says the Great Barrier Reef Marine Park Authority.
The largest coral reef system in the world could be hit by big waves, warmer ocean temperatures, and pollutants washed into the marine environment by floodwaters.
“The summer months are a time of high risk for the Great Barrier Reef,” chief scientist David Wachenfeld told reporters Thursday.
“These are the months where we will see extreme weather events.”
Dr Wachenfeld said the reef could be affected by warmer-than-average air and surface water temperatures and higher rainfall in December and January.
“Beyond that in February and March, which are still part of the maximum risk season, … there is still great uncertainty about what we expect to see,” he said.
“On the one hand we have the forecast of warmer than average conditions, but at the same time since it is a phase of La Nina there is a general forecast of an above average number of cyclones and wetter than average conditions.”
Climate change is making it more difficult to predict the weather on the reef, which is now 0.8 ° C on average warmer than 100 years ago, Dr Wachenfeld said.
“The whole system is changing. Overall, we are increasingly concerned about extreme weather events … these kinds of events will only get worse,” he said.
Climate change remains the biggest threat to the reef and strong global action was needed to reduce greenhouse gas emissions, said Dr. Wachenfeld.
“The world is warming slowly, but it’s not so much the bottom warming that causes reef problems, it’s the extreme weather events that are being driven – marine heat waves, more severe cyclones, extreme flooding,” he said.
“Corals are very sensitive to changes in temperature during the summer and our climate keeps changing every year.”
Coastal development, water quality and fishing also continue to challenge the health of the reef.
“We must act on climate change, but we must also act at the local level”.
Despite recent climate impacts on the reef, such as extreme coral bleaching in 2016, 2017 and 2020, it remains a beautiful, vibrant and diverse ecosystem, said Dr. Wachenfeld.
La Nina occurs when the equatorial trade winds get stronger, changing the ocean’s surface currents and attracting cooler water from the depths.
The intensified trade winds also cause warmer surface waters in northern Australia, potentially leading to heavier rainfall and more tropical cyclones than average.
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