Temperatures on the Great Barrier Reef and surrounding waters have reached their highest levels in at least 400 years due to climate change over the past decade, according to new research published in the journal nature.
This is a stern warning. The survival of the Great Barrier Reef is now largely in human hands. If the world runs primarily on fossil fuels and temperatures continue to rise, corals around the world will face extinction.
“Coral reefs are in danger.”
“Coral reefs are in danger, and if we don’t change our current course, our generation may witness the demise of one of Earth’s greatest natural wonders, the Great Barrier Reef,” said researcher Benjamin B. Benjamin Henley said.
Corals are animals that secrete calcium carbonate skeletons to form coral reefs. Coral skeletons that can grow for centuries allow Henry and his co-authors to look back in time. As they grow, they form bands that scientists can study like growth rings. They contain chemical signatures that indicate heat stress in certain years. The strontium to calcium ratio and the oxygen isotope ratio are particularly related to the water temperature while the coral is still growing.
Before 1900, directly measured sea surface temperature data were inconsistent. They focused on temperatures between January and March, a time when the waters surrounding Australia’s Great Barrier Reef tend to be the hottest.
That’s how they found that three periods, 2024, 2020 and 2017, reached the highest temperatures in four centuries. The most notable year is 2024, which is about 1.73 degrees Celsius warmer than the average temperature reconstructed from 1618 to 1899.
Under heat stress, corals shed the algae that provide them with nutrients and color. This phenomenon is called bleaching, and over time, corals can die as a result. According to a related research article published in the journal Nature, if temperatures are about 1 degree Celsius higher than “normal” summer temperatures for more than two months, large-scale coral bleaching events will occur. nature.
The past year marked the world’s fourth-ever global coral bleaching event, wreaking havoc on reefs around the world and even sparking a race to temporarily relocate coral nurseries to land to save them. Global bleaching events have also occurred in 1998, 2010 and between 2014 and 2017.
Coral skeleton cores assessed by the researchers showed virtually no stress zones before 1980, suggesting that mass bleaching events before then were much less likely. The paper’s authors used climate models to examine potential outcomes with and without human influence, concluding that “human influence on the climate system is responsible for the rapid warming in recent decades.”
Current policies to cut greenhouse gas emissions from fossil fuels are not enough to prevent the situation from getting worse. The global average temperature will still rise by 2 to 3 degrees Celsius compared with before the industrial revolution. Previous research estimates that even a two-degree temperature rise would be enough to wipe out 99% of the world’s coral reefs.
Ove Hogg-Guldberg, a professor of marine studies at the University of Queensland, told a press conference that the Great Barrier Reef faces the prospect of annual bleaching in the near future. “Knowing that we are very close [that] point, I think this will happen within the next 10 years,” Hoegh-Guldberg said. Related articles say that while corals can survive the bleaching process, it usually takes one to twenty years for coral reefs to recover from severe mass bleaching.
With all of this in mind, every little bit we can do to avoid global warming by switching more quickly to clean energy can make a difference for the world’s coral reefs. Some corals may be better able to adapt to a warmer world than others, ensuring the survival of coral reefs even if they are less biodiverse than in the past.
“If we’re going to keep it going, we need to believe in it,” Hogg-Goldberg said. “It’s possible… If we take appropriate action on greenhouse gases, and we find and protect those corals that have a good chance of surviving in these conditions, then we will prepare our coral reefs for the future.”
