A study examining samples from the interior of ancient coral has highlighted the severe impact of climate change on the Great Barrier Reef. Researchers in Australia have found that temperatures in and around the reef over the past decade are the highest recorded in 400 years. This extreme heat has led to five mass bleaching events in the last nine years.
In an article published in *Nature*, the scientists involved in the study warn that rising temperatures, driven by climate change, now pose an “existential threat” to this world-famous natural site. Professor Helen McGregor from the University of Wollongong emphasized the urgency, stating, “The science indicates that the Great Barrier Reef is in peril, and we must heed the science.”
The new findings come from examining the coral itself. Marine scientists have long gathered core samples from coral skeletons, which provide chemical evidence of environmental changes over time. Corals, which are animals rather than plants, can live for centuries and leave behind chemical indicators of their environment.
Australian researchers revisited data from thousands of these cores and compared it with historical sea temperature records from the UK’s Hadley Centre. This analysis revealed that temperatures around the Great Barrier Reef in the past decade were the warmest of the last 400 years. Lead researcher Dr. Benjamin Henley, who conducted the study at Wollongong University, described the recent events as “extraordinary” and concerning for the reef.
Despite the grim outlook, Dr. Henley holds out some hope, suggesting that if global warming can be curtailed, there might still be a chance for the reef and others like it to survive in their current state. Corals, which have evolved to thrive within a specific temperature range, rely on a symbiotic relationship with algae. When sea temperatures rise too high, corals expel these algae, leading to bleaching and eventually turning the corals white. While bleached corals can recover, prolonged heat can prevent this.
Professor McGregor is cautious about declaring a total loss but notes that reefs have endured significant changes over geological time. The critical question is what kind of reef will remain. Currently a UNESCO World Heritage site, the Great Barrier Reef might receive “endangered” status if this research influences the UN organization. Professor McGregor believes this would send a powerful message about the severity of the issue and stressed the need for action to limit global temperature rise, urging that politics should not hinder progress.
