Despite La Nina, Ocean surfaces have not cooled enough to end the worst global coral bleaching event on record. What this means is that many reefs, including the Great Barrier Reef, are again under a rising risk of bleaching and mortality for the coming months. This is unheard of. Never before has a mass coral bleaching event lasted for so long or extended through the period of natural variability related ocean surface cooling called La Nina. Perhaps more ominously, the global coral bleaching and die off that began in 2014 may now be a practically permanent ocean feature of the presently destabilized world climate system.
Cool La Nina is Over
According to NOAA, the periodic cooling of ocean surfaces in the Pacific called La Nina is now over. And since La Nina brings with it a variable related low point of broader Earth surface temperatures, after a few months lag, we can expect the globe to start to warm up again.
(The above map shows sea surface temperature anomalies in the Pacific Ocean on February 9 of 2017. Presently SSTs over the entire Pacific range from about -1.5 C below average to +5 C above average. And as you can see, the Ocean is considerably warmer than normal, despite La Nina. Over the next 1-2 years, this is likely the coolest the Pacific will get. In just one decade’s time, under human-forced warming, it will take a very strong La Nina and a strongly negative Pacific Decadal Oscillation to produce similar sea surface temperatures. Image source: Earth Nullschool.)
Problem is, the Earth is still ridiculously warm, despite La Nina. Temperatures, driven inexorably higher by fossil fuel burning, have probably bottomed out at about 1 degrees Celsius hotter than 1880s averages during December, January and February of 2016-2017.
What this means is that the likely range for annual global temperatures over the next 5 years will be about 1 to 1.3 C above 1880s averages. These readings are so high (the warmest in 115,000 years) and have risen so much, in such a geologically short span of time, that many of the world’s more sensitive species are now being pushed out of their habitats and are undergoing considerable heat-related mortality events.
Great Barrier Reef Under Threat From Bleaching for Second Year in a Row
Perhaps the most obvious of these horrendous fossil-fuel burning spurred instances is the global coral bleaching event that began in 2014. More ominously, it now appears that surface temperatures in the range of 1 C hotter than 1880s and above may well be enough to push the world into a permanent or near-permanent state of global coral bleaching and mortality. What this means is that each year, from now on, there is a considerable risk of widespread coral bleaching. It also means that reefs impacted by bleaching will tend to have shorter cool periods in which to recover.
(NOAA’s 60 percent certainty map shows very widespread coral bleaching expected over the next few months. Presently, bleaching is predicted for the region of the Great Barrier Reef. But other reef systems [see below] fall under higher risks for considerable reef mortality events in the current forecast. Image source: NOAA.)
For February through May of 2017, very warm and warming sea surface temperatures in the Southern Hemisphere are expected to produce extraordinarily widespread risks of coral bleaching. Many areas are predicted to see the highest coral bleaching alert level NOAA has a measure for.
According to NOAA:
Multiple coral reef regions are already experiencing Alert Level 1 bleaching stress (associated with significant coral bleaching). Alert Level 2 bleaching stress (associated with widespread coral bleaching and significant mortality) is expected in the Northern Cook Islands, Southern Cook Islands, the Samoas, Wallis & Futuna, Northern Tonga, Southern Tonga, the Society Archipelago, and the Austral Islands in the next 1-4 weeks. Alert Level 1 bleaching conditions are also expected in the Tuamotu Archipelago in the next 1-4 weeks and in Tuvalu in the next 5-8 weeks.
The prediction map also includes the potential for high alert levels (level 1) for sections of the Great Barrier Reef which last year experienced its worst coral bleaching event on record. Needless to say, a second year of bleaching would be a devastating additional blow to a critical ocean life support system and one of Australia’s priceless national treasures.
Hat tip to George Hayduke