A recent Greenpeace report has started to shed light on the extent of the 2016 summer season’s coral bleaching event throughout Australia’s Great Barrier Reef. Extending some 2300 km, the reef is the largest in the world with a total area about the same as Germany. Globally, reefs occupy 1% of the marine environment but are home to 25% of all marine species including fish, turtles and invertebrates. They are important breeding grounds for many species and provide a vital role in the life of the oceans.
The bleaching event is the worst in history, with 97% effected and 25% dead permanently in a single year.
“Tragically, the ongoing damage from bleaching has been highest in the northern 700km of the Great Barrier Reef all the way up to Papua New Guinea, the most remote and – until now – the most pristine section of the Great Barrier Reef,” says Professor John Pandolfi from the ARC Centre at the University of Queensland.
In 2005, the U.S. lost half of its coral reefs in the Caribbean in one year due to a massive bleaching event. The warm waters centered around the northern Antilles near the Virgin Islands and Puerto Rico expanded southward. Comparison of satellite data from the previous 20 years confirmed that thermal stress from the 2005 event was greater than the previous 20 years combined.
A healthy, resilient reef can either resist a stressful event, like bleaching, or recover from it. When a coral bleaches, it is not dead. Corals can survive if water temperatures return to normal quickly. The danger is that, in the face of frequent bleaching, corals won’t be healthy enough to survive the constant onslaught. Indeed, the ongoing bleaching event has killed nearly half the coral on some northern reefs within the Great Barrier Reef. Extremely high temperatures can even kill corals on the spot. “Corals virtually melt in front of you,” says Lesser, “as the coral cells and algae cells self-destruct simultaneously”.
After corals bleach they become covered in green algae and slime, and eventually collapse. Without a return to cooler temperatures, this is the fate of most corals that have recently experienced bleaching. And these temperatures are likely to arrive in about 20 years, according studies produced to Andrew King, one of two researchers from University of Melbourne, along with researchers from the University of Queensland and the University of New South Wales conducting the works. Model simulations were run showing current temperatures becoming normal by 2030. Following global average temperature records set in 2014, 2015, January, February and March, coral reefs from Florida to India have been devastated by the third mass global bleaching event recorded. The first occurred in the late 1990s, leaving one out of six of the world’s corals dead. Since 1950 more than 90% of the excess heat carbon emissions have trapped in the atmosphere has gone into the oceans. As a result the surface temperature has increased by 1C in just the past 35 years.
Although the cause is clear, it’s also clear that a cabal of climate change deniers, worried tourism operators, and a conservative government have tried to whitewash the environmental disaster unfolding over the Great Barrier Reef.
Mark Eakin, who runs who runs NOAA’s Coral Reef Watch program, explains that the world needs to keep within the 1.5 degrees Celsius for coral reefs to continue thriving. Going past the 2 degrees Celsius limit would doom recovery efforts.