According to marine horticultural scientists, a global meteorological phenomenon where ocean temperatures are below normal across the Great Barrier Reef will not be enough to stop another great coral bleaching.
Dr David Wachenfeld of the Great Barrier Reef Marine Park Authority told the Guardian newspaper in Australia that there is a risk of coral bleaching from heat stress, even in the summer when global warming is now affected by the La Nina climate phenomenon.
The authority on Thursday unveiled its vision for the world’s largest coral reef system, which has suffered three large-scale bleaching events in the past five years.
Clouds, rain and hurricanes can combine to keep the reef temperature low and prevent another bleaching event.
But the U.S. government’s National Oceanic and Atmospheric Administration (NOA) and the Australian Meteorological Agency agreed that ocean temperatures would be about 1C warmer than normal in December and January.
“There is no prediction of a major bleaching event, but it is certainly possible and everything depends on the consideration of the average La Nina,” Wachenfeld said.
“The whole world is hot in degrees, so we can’t rest and call it La Nina. So there will be no heat waves. The world is no longer so simple. ”
The oceans capture about 90% of the additional heat from greenhouse gases, mainly from fossil fuel burning and deforestation.
The authority announced the findings at a scientific workshop Wednesday with marine park managers, scientists, specialists and more than 40 reef industry representatives.
In September, the Meteorological Bureau released a La Nina, which earlier this week said it would last until at least January 2021.
Wachenfeld said La Nina will usually bring more clouds, more rainfall and hurricanes, all of which will help cool water across the Great Barrier Reef.
The reef is about 0.8C warmer than it was 100 years ago, and many shifts have occurred recently. Ten years ago, I said in La Nina that we could not have a bleaching event.
“It’s still cooler than usual, but it’s cooler than it is today, not what it was 20 years ago,” he said.
“The problem with climate change is that background background conditions are warming [they] That may not have been the case. ”
I think the reefs are basically unstable due to climate change.
“It simply came to our notice then. The weather was not particularly damaging to the reef.
“But global warming means that there is a lot of heat energy that is causing extreme climate change in many of the world’s ecosystems.”
He said an urgent global action plan was needed to reduce greenhouse gas emissions.
Asked if he was worried about the coming months, he said, “We live in a world with a changing climate, so there is always background anxiety. We are in a specific area.”
Dr. William Scurving of Coral Reef Watch, Noah, presented a model of the possible thermal stress on the reef in the coming months for discussion on Wednesday.
He told the Australian Guardian newspaper that according to data from Noah and the Meteorological Agency, widespread heat stress could occur across rocks, “enough to bleach corals but often not enough to kill them.”
Scurving said: “This is a long way off, but all indications are that the reef will have a stressful time this summer and could come in several forms. If there is no hurricane it can be a heat stress, and if there is more rainfall it can be removed. ”
Over the past few decades, Scurving said, a La Nina event could have prevented excessive heat stress due to high sea surface temperatures.
Background temperatures remain high due to climate change. This means that there is less workload to raise the temperature from sunlight to bleaching levels. ”
But Skirwin said the arrival of hurricanes and tidal waves relative to local weather could keep the water cool but the hurricanes could not be predicted for months.
The Meteorological Agency says there is more than 67% chance of four typhoons in eastern Australia this summer in Australia.
Hurricanes can keep water cool and protect corals from thermal stress, which can cause physical damage to reefs if they are large enough.
Rainfall can cool the reefs, but flooding the land can cause additional pollution to flow into the reef water.
The Authority says that the proliferation of star fish with a coral-eating thorny crown continues to affect it. This is especially true in the central and southern regions of the reef.