were bathed in extremely warm water for months This area of the reef had been considered its most pristine and the 2016 bleaching event was the worst ever recorded at the site Most of the southern reefs remained largely intact due to heavy rain and cloud cover during the summer Climate change damage does not stop with bleaching Climate change results primarily from fossil fuel burning which raises temperatures in the atmosphere by releasing greenhouse gases The most plentiful greenhouse gas in the atmosphere is carbon dioxide CO2 When carbon dioxide dissolves in the ocean it reacts with water to become carbonic acid which makes water more acidic Corals are affected by acidification because of their calcium carbonate skeletons Already existing coral skeletons may be corroded by the acid The new coral growth may be slowed resulting in weaker reefs that are more likely to erode Recent studies show that some coral species may be able to control their internal acidity and cope with increasing levels of acid in the water But studies indicate future acidification may damage the GBR 10 DOCUMENTING DEATH Diver Richard Vevers was most disturbed by the smell When we got back on the boat we realized we just stank stank of the smell of rotting animals Vevers is chief executive of the Ocean Agency an organization he founded to bring attention to environmental problems He photographed Lizard Island reef which was affected by the 2016 GBR bleaching event He took pictures of the reef before bleaching began just after bleaching started and finally weeks later when its effects became obvious The healthy reef was luxuriant with life The dying reef was brilliant white deceptively beautiful But several weeks later Vevers said It was one of the most disgusting sights I’ve ever seen 10 Hard corals were blanketed by algae and seaweed Soft corals were decomposing their flesh dripping off the reef structure Other animals had disappeared The reef was no longer diverse and colorful Its corals were all dead
OTHER IMPACTS The GBR is threatened by more than climate change It is damaged by shore-based pollution including toxic chemicals from industry and nutrient runoff from agriculture and sewage Excess nutrients speed up algal growth blocking sunlight and causing algae to overgrow the reefs In addition some people cause direct damage to reefs They drop anchors or carry out dredging and trawling breaking off pieces of the reef structure They use unsustainable and destructive fishing methods The single biggest thing we can do to protect the Reef for the future is to greatly reduce greenhouse gas emissions as soon as possible 11 David Wachenfeld director of reef recovery at the Great Barrier Reef Marine Park Authority Finally similar to marine organisms throughout the oceans residents of the GBR are succumbing to plastic pollution Polyps are filter feeders They draw into their bodies whatever is present in the water passing over them This includes microplastics tiny beads of plastic ground down by waves until they are small enough to become coral food But corals cannot break down plastic which remains in their digestive systems and may prevent them from digesting real food When corals eat microplastics they can starve THE FUTURE OF THE GBR Research released in 2016 suggests the GBR may be in even more danger from climate change than previously suspected Temperature spikes are known to kill corals but temperature changes are not uniform across the reef When part of the reef receives a 11
World Heritage Area and Region Boundary Far northern management area Great Barrier Reef Marine Park 345 400 sq km Coral reef 400 km 200 miles Cairns Cooktown management area PACIFIC OCEAN Conversions sq km 345 400 Cairns Townsville Whitsunday management area sq miles 133 360 Mackay Capricorn management area Townsville QUEENSLAND Mackay AUSTRALIA Rockhampton Gladstone Australia's Great Barrier Reef
pulse of warmth a surge of gently warmed water a few days before a temperature spike this short time of adjustment prepares the reef and makes it more able to survive the temperature spike But as temperatures rise those pre-spike pulses will stop Simultaneously single temperature spikes will increase dramatically These changes will occur within the next 40 years and unless greenhouse gas emissions are drastically reduced by the 2050s the corals could die from bleaching Stress from climate change plus stresses from pollution and other human actions are combining to make the future of the GBR precarious at best And what is happening to the GBR is happening to reefs around the world not only rising temperatures and acidity but also plastics pollution overfishing and damage due to runoff construction and vandalism The devastation is rapid Why are people letting this happen What can be done about it 13
