Climate Council

Published date July 5, 2018

Lethal Consequences: Climate Change Impacts on the Great Barrier Reef


  • Unprecedented bleaching events on the Great Barrier Reef in 2016 and 2017 have resulted in mass coral mortality.
  • Rising sea surface temperatures over the past century have resulted in more frequent and prolonged global marine heatwaves.
  • By 2034, the extreme ocean temperatures that led to the 2016 and 2017 bleaching events may occur every two years. Such a short period between bleaching events is not sustainable as the development of coral assemblages takes at least a decade.
  • Between 1925–1954 and 1987–2016 the global average frequency of marine heatwaves increased by 34% and the global average duration increased by 17%.
  • Global sea surface temperatures have increased by 0.2°C from 1992 to 2010, increasing the odds of more frequent and prolonged marine heatwaves.
  • The return period for global bleaching events has decreased from 27 years in the 1980s to only 5.9 years now.
  • In the future, regional-scale bleaching can be expected to occur in hot summers in both El Niño and La Niña years.