The third global coral bleaching event that began in 2014, continued to sweep around the globe in 2016. Early in the year, scientists were concerned that the bleaching would hit the Great Barrier Reef – and it did: The Coral bleaching event in the Great Barrier Reef is the biggest in known history with the Bureau of Meterology recording the highest sea surface temperatures ever. (Photo – HANDOUT AFP/Getty Images)
See our update on the 2016 and 2017 coral bleaching events and the devastating effects on the Great Barrier Reef, see: Can the Great Barrier Reef be Saved?
Biggest Threat to Coral Reef is Climate Change
Over 1000 KM of northern GBR have been affected by the bleaching. This region escaped with minor damage in two earlier bleaching events in 1998 and 2002 but has lost an average of 67 percent of its shallow-water corals in 2016
Agricultural Run-off and Coastal Development are not the Problem
Australian federal and state governments have increased their investments to reduce the run-off from agriculture and development along the coast that directly impacts the reef. But scientists have been warning for years that the biggest threat to the reef is climate change. The ongoing bleaching event bears this out.
Prof. Terry Hughes, a coral scientist and Director of the Australian Research Council (ARC) and Coral Reef Studies at James Cook University, undertook extensive aerial surveys at the height of the bleaching in 2016. According to the ARC surveys, the worst affected area – was a 435 mile stretch of reefs in the northern region of the Great Barrier Reef. This region is farther away from human impact and has some of the most pristine reefs of the GBR, and yet they are not resistant to the effects of a warming ocean. (Photo – @
Rising Ocean Temperature is the Problem
Current scientific research directly connects the increase in coral bleaching events to ocean warming. The Bureau of Meterology has been recording sea surface temperatures (SST’s) since 1900 and SST’s have been increasing. While the El Nino can have year-to-year effects on temperatures, longterm coral records do not show any evidence of coral bleaching, even though the reefs have gone through many El Ninos. It’s only been since 1998 when increasing SST’s combined with the extra temperature spikes from El Niño have overwhelmed coral health. The coral bleaching events of 1998, 2002 and this current GBR bleaching event, the areas of the reef that bleached matched “perfectly” the areas with unusually high SST. This map shows trends in global ocean heat content, from the surface to 2,000 meters deep. (Graph – Yale Environment 360, March 2015)
The Link Between Coral Bleaching and Human Caused Climate Change is Very Clear
Prof John Pandolfi, leading coral scientist at the University of Queensland says, “The link between high SSTs and global bleaching is very clear, and the link between climate change and SSTs is very clear. Finally the link between global emissions and the rise of CO2 and SSTs is very clear.”
“This all adds up to the human-caused element for this bleaching episode. It seems clear that if the ocean’s SST were not rising so fast we would not be experiencing these severe bleaching events on a global scale.“ (Photograph: Courtesy of Reef Explorer Fiji Ltd.)
The Inconvenient and Incontrovertible Truth
Scientists have been studying the ocean warming trend, using data that goes back to the 1870’s. It’s been discovered that the ocean absorbs over 90% of the heat from man-made global warming. A study published in the journal Nature on January 18, 2016 puts the cause of ocean warming squarely on human-caused activities especially the burning of fossil fuels like coal, oil and gas that add greenhouse gases. The study states that the ocean is absorbing twice as much heat trapped by green house gases as it did 18 years ago. Scientific evidence indicates that the ocean’s ability to absorb this excess heat is weakening. Coral bleaching is just one sign of the weakening system due to man-made. (Photo – XL Catlan Seaview survey/AFP/Getty Images)