Two-thirds of Great Barrier Reef bleached

Australia’s Great Barrier Reef is suffering from another massive bleaching event, the first time in memory such episodes have hit in back-to-back calendar years

GREAT BARRIER REEF (World heritage area) Largest living structure on Earth nurtures around 1,500 species of fish

AUSTRALIA

Most severe bleaching in 2016

Most severe bleaching in 2017

No or negligible bleaching

2017 bleaching hit central section, causing damage to spread 640km further south

CAUSES OF BLEACHING

Rising water temperatures resulting from natural warm currents

Exacerbated by man-made climate change, as oceans absorb around 90% of increase in Earth’s heat

Latest damage occurred without El Niño weather pattern, associated
with 2016 and earlier bleaching events

WHAT IS BLEACHING

Healthy coral: Algae, known as zooxanthellae, lives in coral tissue,
providing primary food and colour

Stressed coral: As water approaches 31°C, coral polyps expell algae from tissue

Bleached coral: Without algae, coral turns white and loses main source of food

Coral can recover if normal conditions return, but if stress continues
it dies

CORAL SEA

250km 150 miles

Sources: Australian Research Council – James Cook University, NOAA