Intensifying climate change led to a record breaking marine heatwave in 2016 that caused extensive coral death and radical changes in coral systems on the Great Barrier Reef, according to new research released in Nature today.
The report “Global warming transforms coral reef assemblages“, led by ARC Centre of Excellence for Coral Reef Studies Director, Professor Terry Hughes, shows that the northern third of the Great Barrier Reef was most severely affected by the extended marine heatwave, with almost 30% of the Great Barrier Reef losing two-thirds of coral between March and November 2016.
Climate Councillor and ecologist Professor Lesley Hughes said the report shows the catastrophic damage climate change-driven mass coral bleaching has caused to one of the world’s most treasured natural icons.
“This research confirms that enormous numbers of corals died in the northern third of the Great Barrier Reef within just three weeks as direct result of rising ocean temperatures, driven by worsening climate change,” she said.
“This study shows the vulnerability of the reef’s coral systems to the mass bleaching event, with temperature-sensitive coral species dying after being hit by the marine heatwave.”
KEY REPORT POINTS:
- The 2016 bleaching event triggered an unprecedented loss of corals in the northern third of the Great Barrier Reef, and to a lesser extent, the central third, with almost no heat-stress mortality occurring further south.
- Initially, at the peak of temperature extremes in March 2016, many millions of corals died rapidly in the northern third of the Great Barrier Reef over a period of only 2–3 weeks.
- Fast-growing staghorn and tabulate corals suffered a catastrophic die-off, transforming the three-dimensionality and ecological functioning of 29% of the 3,863 reefs comprising the world’s largest coral reef system.
- In the northern, 700-km-long section of the Great Barrier Reef (from 9.5–14.5 °S), where heat exposure was the most extreme, just over 50% of the coral cover on reef crests was lost within eight months.
- More broadly, throughout the entire Great Barrier Reef, including the southern third, where heat exposure was minimal, coral cover declined by 30% between March and November 2016.
- Across the entire Great Barrier Reef, nearly 35% of individual reefs experienced at least 4°C-weeks, and nearly 21% were exposed to 8°C-weeks or more of accumulated heat stress in 2016.
Climate Councillor and climate scientist Professor Will Steffen said Australia’s woefully inadequate climate and energy policy had led to the nation’s greenhouse gas pollution levels reaching disappointing new heights.
“The burning of fossil fuels such as coal and gas, continues to drive Australia’s greenhouse gas pollution levels higher and higher, all the while climate records topple. In this month alone we have witnessed the nation’s hottest April day on record, with a national average temperature reaching 34.97 °C on April 9,” he said.
“These records are part of a long-term warming trend, with seven of the ten hottest years on record in Australia all occurring since 2005.”
The Climate Council called on the Federal Government to urgently move to protect the Great Barrier Reef through the rollout of strong and credible climate and energy policy.
“This report highlights that the unprecedented back-to-back mass coral bleaching events on the Great Barrier Reef in 2016 and again in 2017 are a strong warning about further reef decline unless serious climate change action is taken,” said Professor Steffen.
“This additional research provides more evidence that the Government’s focus on water quality measures are not enough to protect the Great Barrier Reef from catastrophic damage,” he said.
“We need more than band aid, temporary solutions. The source of the problem is clear, and unless our Federal Government works in collaboration with other countries around the world to cut rising greenhouse gas pollution levels, through transitioning to clean, affordable and reliable renewable energy and battery storage technology, we will see such biological catastrophes become even worse,” said Professor Lesley Hughes.
To view the full report in Nature please click here.
For more information please contact Climate Council Senior Communications Advisor Alexia Boland on 0438 972 260.