Coral Reefs are Dying Because of Climate Change

Pro: Coral Reefs are Dying

From The National Oceanic and Atmospheric Administration:

Climate change is the greatest global threat to coral reef ecosystems.  Scientific evidence now clearly indicates that the Earth’s atmosphere and ocean are warming, and that these changes are primarily due to greenhouse gases derived from human activities.

As temperatures rise, mass coral bleaching events … are becoming more frequent.  Additionally, carbon dioxide absorbed into the ocean from the atmosphere has already begun to reduce calcification rates in reef-building and reef-associated organisms by altering seawater chemistry through decreases in pH.  This process is called ocean acidification.

Climate change will affect coral reef ecosystems, through sea level rise, changes to the frequency and intensity of tropical storms, and altered ocean circulation patterns.  When combined, all of these impacts dramatically … [harm coral reef] ecosystems … around the globe.

https://oceanservice.noaa.gov/facts/coralreef-climate.html

---

Con: Coral Reefs are Thriving

Coral reefs are thriving around the globe.  Coral has existed continuously for the past 40 million years, surviving temperatures and carbon dioxide levels significantly higher and lower than what is occurring today.  Since the peak of the last glacial maximum 33-26 thousand years ago, global average temperature reached its highest point approximately 7,000 years ago, at least 1 or 2 degrees C higher than today, during which coral reefs thrived.

Coral requires warm water, not cold water, to live.  Coral cannot live outside of tropical or subtropical waters. (See Figure 1.)  Coral reefs thrive in locations throughout the globe where temperatures range from site to site by as much as 20 degrees Fahrenheit, from the most Northern or most Southern sites to the most equatorial sites.  The temperature at coral reef sites range by over 20 degrees Fahrenheit from Summer to Winter at some locations around the world.  Thus, coral reefs have proven to thrive in a substantial range of temperature environments, including temperatures that exceed those where coral bleaching has occurred.    

As Earth continues its modest warming since the peak of the Little Ice Age 400 years ago, coral reefs have extended their range toward the poles while still thriving at and near the equator.

Temperature Swings: Short-term heatwaves or cold snaps can cause bleaching events, but historically, such events have occurred long before the recent warming since the peak of the Little Ice Age.  Moreover, studies show coral can and have been adapting to the gradual long-term pace of global warming that has occurred since the peak of the Little Ice Age.  History shows that cold snaps can harm coral much worse than warm spells.  In 2010, colder ocean temperatures off the coast of Florida killed more coral than any warm-water event.  And, despite these events, coral reefs recover over the course of several years or sometimes, even quicker.  

It was a depressing, if expected inevitability when Western Australia’s Rowley Shoals showed the first signs of mass coral bleaching earlier this year, but a follow-up survey has found a remarkable recovery looks likely to preserve the reef’s near-pristine health — at least for now.

Tom Holmes, the marine monitoring coordinator at the WA Department of Biodiversity, Conservation and Attractions, said that while his team was still processing the data, it appeared the coral had pulled off an “amazing” return towards health over the past six months.

“We were expecting to see widespread mortality, and we just didn’t see it … which is a really amazing thing,” Dr Holmes said.

Source:https://www.abc.net.au/news/2020-11-06/coral-reef–at-rowley-shoals-recovers-from-bleaching/12840302

A poster child for coral alarmism is the Great Barrier Reef.  The Great Barrier Reef is 20 million years old, and it has survived significantly warmer and colder temperatures than today.  Although the Australian Institute of Marine Science documented that approximately 22 percent of the reef experienced recent bleaching (not 93 percent, as reported in alarmist media stories), 75 percent of the bleached portion of the Reef is expected to make a full recovery.  Poor water quality resulting from nearby coastal development is the main culprit for bleached reef areas that do not recover.  Evidence shows much of the bleached coral in the Great Barrier Reef has already recovered and the rest is continuing to recover.

Figure 1: Coral Reef Locations

Scientists are learning more about the resilience of coral all the time.

Reef building corals depend on energy from photosynthesizing symbiotic algae. But their symbiotic relationship requires careful maintenance. So coral naturally add and subtract symbiotic algae as the seasons change. During the winter, coral increase their symbiotic algae as lower light reduces photosynthesis. Each summer as light intensity increases, they expel symbionts. Bleaching is just an extreme of that behavior. After bleaching, coral can quickly replace their symbiotic algae within days or months with no resulting mortality.

Scientists are increasingly observing that coral can acquire very different symbiotic algae with different genetics. To adapt to changing climates corals don’t require thousands of years to evolve. Coral get instantaneous genetic upgrades simply by acquiring new symbiotic algae. Acquiring different symbiotic algae allowed coral to adapt to dramatic temperature changes as Ice Ages came and went. And acquiring new symbiotic algae now allows coral to rapidly adapt to 60-year changes caused by ocean oscillations.

Decreasing Ocean pH Due to Increasing Carbon Dioxide:  Climate alarmist like to call this “Acidification”, but no mainstream oceanographer believes that the oceans will become acidic, in the next several thousand years, though some believe that ocean pH may be lowering fractionally. 

However, it would require several hundreds of years of detailed ocean acidification data to accurately determine the natural trends and fluctuations of ocean acidification that would allow an accurate comparison to ocean acidification since the increase in anthropogenic carbon dioxide in the atmosphere since 1850.

Further, there is no evidence of decreased populations of shrimp, clams, snails and other mollusks and crustaceans.  In fact, the global harvesting and ocean culturing of these sea animals have not experienced any reductions in volume in the past 50 years, let alone since the 1850s when carbon dioxide levels were fractionally lower.