By Marc Hendrickx – Re-Blogged From WUWT
From the “science eventually self-corrects” department, new science showing coral bleaching of the Great Barrier Reef is a centuries-old problem, well before “climate change” became a buzzword and rising CO2 levels were blamed.
New paper shows coral bleaching in GBR extending back 400+ years.
[This] busts myths promulgated by alarmist Dr. Ove Hoegh-Guldberg see for instance
“The science tells us that exceeding 2°C in average global temperature will largely exceed the thermal tolerance of corals today. It is already happening. Rolling mass bleaching events, unknown to science before 1979, are increasing in frequency and severity.”
Also see the news report from The Australian https://www.theaustralian.com.au/news/nation/coral-bleaching-a-centuriesold-problem/news-story/33b3cbd7cd3b784322c0a7bc10e98eb6
Here is the paper: (open access)
Reconstructing Four Centuries of Temperature-Induced Coral Bleaching on the Great Barrier Reef
Mass coral bleaching events during the last 20 years have caused major concern over the future of coral reefs worldwide. Despite damage to key ecosystem engineers, little is known about bleaching frequency prior to 1979 when regular modern systematic scientific observations began on the Great Barrier Reef (GBR). To understand the longer-term relevance of current bleaching trajectories, the likelihood of future coral acclimatization and adaptation, and thus persistence of corals, records, and drivers of natural pre-industrial bleaching frequency and prevalence are needed. Here, we use linear extensions from 44 overlapping GBR coral cores to extend the observational bleaching record by reconstructing temperature-induced bleaching patterns over 381 years spanning 1620–2001. Porites spp. corals exhibited variable bleaching patterns with bleaching frequency (number of bleaching years per decade) increasing (1620–1753), decreasing (1754–1820), and increasing (1821–2001) again. Bleaching prevalence (the proportion of cores exhibiting bleaching) fell (1670–1774) before increasing by 10% since the late 1790s concurrent with positive temperature anomalies, placing recently observed increases in GBR coral bleaching into a wider context. Spatial inconsistency along with historically diverging patterns of bleaching frequency and prevalence provide queries over the capacity for holobiont (the coral host, the symbiotic microalgae and associated microorganisms) acclimatization and adaptation via bleaching, but reconstructed increases in bleaching frequency and prevalence, may suggest coral populations are reaching an upper bleaching threshold, a “tipping point” beyond which coral survival is uncertain.
This figure (especially panel B) suggests that there was bigger bleaching events in the past:
In the discussion section they say:
Both our reconstructed and the observational GBR bleaching records show maximum bleaching during 1998 across the whole GBR (Figure 3) although this is not scaled for observational effort.
Gosh, what happened in 1998? A super El-Niño, that’s what, and that natural cycle event wasn’t caused by man. Note all the warm ocean water near Eastern Australia where the GBR is located.
The UUIC writes:
Droughts in the Western Pacific Islands and Indonesia as well as in Mexico and Central America were the early (and sometimes constant) victims of this El Niño. These locations were consistent with early season El Niños in the past. A global view of the normal climatic effects of El Niño can be seen below.
Image by: CPC ENSO Main Page
But, Dr. Ove Hoegh-Guldberg makes his living blaming man-made climate change for just about every ill associated with the GBR, so I’m pretty sure he won’t like this paper as it draws attention to the obvious: Coral bleaching of the GBR is not a new problem unique to our time-frame.