DATE: February 24, 2020
SNIP: Over the next 20 years, scientists estimate about 70 to 90% of all coral reefs will disappear primarily as a result of warming ocean waters, ocean acidity, and pollution.
Expand that out to 2100 and it’s “looking quite grim,” says Renee Setter, a marine scientist at the University of Hawaii in Manoa. By 2100 there will be nearly zero suitable coral habitats remaining, eliminating nearly all living coral reef habitats.
Recent research, presented at the Ocean Sciences Meeting 2020, is focused on transplanting lab-grown corals into dying reef ecosystems in hopes that it will revive the reefs. While there have been promising results in the short term, by 2100 ocean environment will be too harsh for corals to survive.
In recent decades scientists have become increasingly alarmed at what looks like the inevitable fate of coral reefs. Scientists have tried to use underwater speakers to play continuous sounds of healthy coral reefs in hopes this entices marine life to return. While this, along with other artificial means to encourage coral reef growth has been successful to some degree, the increasingly harsh environment will lead to coral reef die-off.
Corals live in a mutually symbiotic relationship with photosynthetic algae, called zooxanthellae. Corals make up the hard calcium carbonate structure of coral reefs and provide protection and a home for zooxanthellae. In return, the zooxanthellae provide nutrients to the coral.
When surface ocean temperatures warm beyond a narrow livable range, the coral kicks out the zooxanthellae, causing “coral bleaching” and often times the eventual death of the coral. A similar process occurs when corals are exposed to pollutants running off of the nearby land.
Ocean acidification also plays a role in the death of corals. The more CO2 in the atmosphere, the more CO2 is absorbed into the oceans, causing the oceans to become slightly more acidic. This increased acidity makes it harder for corals to build their calcium carbonate skeleton and makes their skeletons more fragile and susceptible to breaking.
Warming ocean temperatures and ocean acidification are both a direct result of the increased CO2 emitted by humans, while the increased pollution runoff is primarily a result of expanding agricultural land and the use of fertilizers.