3-Year Global Coral Bleaching Event Officially Over; 70% Of Planet's Corals Bleached Or Killed
n the Equatorial Pacific, the chances for an ocean-surface-cooling La Nina are on the rise (more on this later). But even with a cool pool of water upwelling in this key climate region, the risk to corals in a record-warm world remains high.
This risk comes despite the fact that by June of 2017, NOAA had officially declared an end to the longest global coral bleaching event on record. The event lasted from 2014 to 2017 and impacted multiple major coral reefs for 2-3 years in a row. According to NOAA, the event affected more reefs than any other previous global coral bleaching event. Meanwhile, some reefs that had never before seen significant bleaching — like northern sections of the Great Barrier Reef — saw severe damage.
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(A portrait of the world’s worst global coral bleaching event shows that 70 percent of the world’s corals took a major hit. Image source: NOAA.)
In total, more than 70 percent of the worlds reefs experienced heat stress capable of producing bleaching. An extent never before attained. One that is difficult to imagine. The NOAA graphic above provides some context of the terrible expansiveness — with dark red areas representing widespread bleaching and significant coral mortality and light red regions representing significant coral bleaching over the totality of the 2014 to 2017 event.
To be very clear, the primary driver of this very widespread event was a human-forced warming of the world through fossil fuel burning. This driver has resulted in sea surfaces that are, in many regions, more than 1 degree Celsius above 19th Century temperature averages. Temperatures that are now enabled to spike to 3, 4, or even 5 C above average during variable warming events like the recent strong 2015-2016 El Nino. Temperatures that now never really back off to previous lows. A regime that provides little respite for corals.
EDIT
https://robertscribbler.com/2017/09/18/longest-global-coral-bleaching-event-officially-at-an-end-but-severe-worldwide-risk-to-corals-remains/
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