Truths about Coral Bleaching: CO2 Warming vs Reduced Clouds Cover?
22 hours ago Guest Blogger
Jim Steele
The coral that now form our modern reefs evolved 240 million years ago during the Age of Dinosaurs when coral formed a marvelously fluid symbiotic relationship with symbiodinium algae. The new algae symbionts absorbed CO2 and produced sugars via photosynthesis for the coral. In turn coral respiration produced CO2 that supported the algae’s photosynthetic production. This symbiotic relationship evolved when CO2 was 4 times above today’s concentrations and global temperatures were several degrees higher. Takashima (2006) reports the mid-Cretaceous earth “surface temperatures were more than 14°C higher than today,” a time when dinosaurs roamed Antarctica. Atlantic warm pool sea surface temperatures reached a maximum of 42°C (107°F).
That evolutionary history explains why shallow-water coral are now restricted to the warmest ocean waters. Graphic A shows the location of today’s coral. Graphic B shows the oceans regional temperatures. Corals are most abundant in the warmest waters of the Indian Ocean and Western Pacific Warm Pool, also known as the Coral Triangle. There, sea surface temperatures (SST) reach 28-30°C (82-86°F), sometime a little higher.
In contrast, the eastern tropical Pacific, experiences cooler SSTs due to upwelling typically in the range of 20°C (68°F). With the eastern tropical Pacific 8-10°C (14-18°F) cooler than the tropical western Pacific, there coral reefs are scarce and restricted to much smaller Atlantic and eastern Pacific warm pool regions. So why are today’s warm temperatures blamed for coral bleaching? Why does CNN report bleaching as catastrophic?
https://wattsupwiththat.com/2025/01/29/truths-about-coral-bleaching-co2-warming-vs-reduced-clouds-cover/
