Via Kenneth Richard above 2. December 2021
Over the past several decades, Great Barrier Reef (GBR) warming and coral bleaching have often been attributed to anthropogenic greenhouse gas emissions and/or El Niño events. But a new study shows a much larger and stronger correlation between natural cloud cover’s modulation to solar radiation, shallow-water warming, and bleaching.
It has taken more than 260 years for the net total amount of forced radiation from CO2 to be assumed to increase in total 1.82 W/m².
But one new research revealed that the commonly observed cloud cover of 20% over the GBR indicates this region add 30 W/m² direct solar radiation for weeks, months at a time. This significantly warms the shallower waters and, more importantly, the enhanced shortwave radiation causes corals to undergo permanent UV bleaching.
“The sea surface temperature in the delayed area (SST) is correlated with the total cloud cover over the Great Barrier Reef (GBR) and the direct radiative force of the shortwave cloud.”
“SST on GBR is more highly correlated with aerial cloud cover than with large-scale El Niño – Southern Oscillation signals.”
“Local reduced cloud cover plays an important role in shallow water warming over the GBR and the occurrence of thermal coral bleaching events.”
Evidence shows that natural coral bleaching events have been going on for centuries, millennia and beyond.
Earlier this year, we highlighted a 2021 study that claimed ‘Repetitive’ coral bleaching throughout during the warmer Holocene than today.
Now, another novel study even used evidence from 150-year-old paintings to show that bleached coral was commonly observed during the cold Ice Age. Coral bleaching can and does usually occur during cold periods and/or in winter (Hoegh-Guldberg and Fine, 2005, Saxby et al., 2003, Hoegh-Guldberg and Fine, 2004).
The author asserts that what is “widely believed” about human-driven coral bleaching is completely false, as bleaching is “not a modern phenomenon” but a “normal way”. to adapt to changes in water temperature”. Coral bleaching has been documented in the 1930s, 1860s (paintings) and 1570s.
“It is believed that coral bleaching is a phenomenon that was first observed less than 50 years ago. However, coral bleaching was first observed more than 150 years ago by Eugen von Ransonnet, during what is known as the Little Ice Age (about 1300 – about 1900).
“Yonge in 1931 discovered that living corals on the Great Barrier Reef bleached after exposure to high temperatures (Oliver et al. 2009; Yonge and Nicholls 1931), and Kamenos and Hennige (2018) recorded traces of coral bleaching in stony core corals from the Great Barrier Reef as far back as 1575. Therefore, coral bleaching is an ever-present phenomenon as a normal way of adapting to change. changes in water temperature, and is not a modern phenomenon. ”
There is even evidence that coral bleaching is than likely to occur in cooler water. Example: The Coral Triangle is 2-8°C warmer than the surrounding “marginal” or “low temperature” areas, but cooler areas record more bleaching events than the Triangle Coral.
“Such bleaching of corals over the past decades has been reported particularly from marginally lower temperatures of the entire range of grass corals (Goreau and Hayes 1994; Oliver et al. 2009; Burke et al. 2011). On the other hand, it is generally not, or to a much lesser extent, reported from the central region, the so-called Coral Triangle (Oliver et al. 2009; Burke et al. 2011; Ridd 2017), where Water temperatures are about 2–8 °C higher and more stable than in marginal areas (Tchernia 1980; Tomczak and Godfrey 2002). ”
So, in summary, another claim about the unprecedentedness of modern warming and bleaching in the GBR and their alleged link to anthropogenic greenhouse gas emissions has been tainted by the observational evidence.