3rd bleaching event in 5 years at The Great Barrier Reef

by TNP Editor 2020-4-19

Australia’s Great Barrier Reef is suffering from its third massive coral bleaching event since 2016.  Terry Hughes, a top coral expert at the ARC Centre of Excellence for Coral Reef Studies at James Cook University, surveyed the reef system and reported severe levels of bleaching in all three sections – north, central and south – of the Great Barrier Reef.

Last3bleachingEventsThe Great Barrier Reef experienced five mass bleaching events – in 1998, 2002, 2016, 2017 and 2020.

This third event in five years is the most widespread and it greatly affected the deep water coral reefs.

February 2020 saw the highest monthly sea temperatures ever recorded at the Great Barrier Reef since 1900.

Past coral bleaching events typically took place during El Nino, a climate phenomenon that sees the reversal of ocean current flow and the warming of the South Pacific  waters.

With rising ocean temperature around the globe, however, these bleaching events are occurring more frequently and more widespread.

Climate change “El Niño”

el nino

Courtesy: http://www.denizbilimi.com

by Austin Yeung 2015-06-13

El Niño, ‘the Christ Child’, was first named by fishermen in Peru during Christmas when they noticed unusual warm currents affecting the Pacific coastline of South America. It is an anomaly – a prolonged warming of the central and east-central Pacific Ocean sea surface temperatures (SST).

El Niños often happen in intervals between two to seven years, and last nine months to two years. When this El Niño warming happens for only a brief 7-9 months, it is classified as an El Niño “condition,” whereas when the El Niño period lasts longer, it is known as an “episode.”

Coral reefs, rainforests of the oceans, are susceptible to coral bleaching as a result of high water temperatures.  Bleaching occurs when coral tissues expel algae, known as zooxanthellae, that reside in the coral, and die.  The entire coral reef then turns white as if it were bleached.  That’s why coral scientists pay attention to such ocean warming events as El Niño.

Currently, NOAA just declared that the most recent El Niño commenced in March 2015. The latest forecast showed a 90% chance of the El Niño continuing in the fall and an 85% chance into winter of 2015/16. Many anticipated a stronger El Niño since the 1998 El Niño occurrence. With an increase of 4°C in SST, the 1998 happening of the El Niño undersizes the current El Niño, which saw a greater than 1.9°C SST. Although this is not a weak El Niño appearance, it is not a strong one either.

Contine reading