:: Saima Binte Kashem ::
Great barrier reef of Australia is the world’s largest coral reef system.It is composed of over 2,900 individual reef and 900 islands stretching for over 2,300 kilometres. It is only living thing visible from space which is longer than great wall of chaina. But this natural gift is threatened in recent years by the impact of global warming.
Global warming has caused such extensive damage to the Great Barrier Reef that scientists say its coral may never recover.According to a study published in the journal Nature on 3 April , 2019 , that baby coral in Australia’s Great Barrier Reef have declined by 89% due to mass bleaching in 2016 and 2017.Deadly back-to-back bleaching events devastated the reef, and now its ecosystem is struggling to recover. Not only have ocean heat waves led to a decrease in new coral, but also a change in the types of coral species being produced.The study found that a majority of the northern region’s coral has not been able to recover following mass bleaching events, leading to a decline in new coral as well. “Dead corals don’t make babies,”said the study’s lead author, Professor Terry Hughes.
According to the study, the biggest decline in replenishment came from the reef’s dominant species of adult coral, called Acropora, which supports thousands of other species. The study shows that reef resilience is now severely compromised by global warming.Scientists expect the coral may recover over the next five to ten years — but only if another mass bleaching event doesn’t occur during that time.
The Great Barrier Reef has gone through four mass bleaching events due to above-average sea temperatures in 1998, 2002, 2016 and 2017. Time periods between future bleaching events are expected to continue to shrink as global warming intensifies.
Bleaching occurs when corals are stressed by unusual environmental changes, such as increased sea temperature. They respond by expelling the symbiotic algae living in their tissues, causing the coral to turn white. Without the algae, the coral loses its major source of food and often can’t survive. Widespread coral bleaching during back-to-back summers was particularly toxic, as it did not leave enough time for the corals to fully recover.
There’s only one way to fix this problem and that’s to tackle the root cause of global heating by reducing net greenhouse gas emissions to zero as quickly as possible, So that we can keep this largest coral reef alive for the well being of our global environment.
Writer is a student of Department of Environmental Science and Disaster Management, NSTU