Coral Bleaching and the Rise of Ocean Ghost Reefs

7 mins

As global warming heats up our oceans to unprecedented levels, scientists warn that all coral reefs will be under threat by 2050 unless collective action happens now. Florida TV weather and climate expert Jeff Berardelli reports

Humour me for a moment. You’re the buoyant and bright clownfish from the famous 2003 Walt Disney movie Finding Nemo returning from a day trip away from your home; a colourful, vibrant and bustling city under the sea. As you near your home city you realise something seems amiss. As you glide ever closer you’re startled to see the city is nothing like you left it. It’s dark, dreary and vacant of life. It’s a ghost town. ‘This can’t be’ you say, ‘I must have taken a wrong turn’. With worry and determination you forge ahead in search of your family, your friends, and the familiar places which harbour your fondest memories. But at every turn all you encounter are abandoned streets and buildings. No sign of life. No sign of your family and friends. Everything you once knew is nothing but a memory. Your once vibrant town, is now a ghost town. Let’s call them ghost reefs.

Ok, thank you for letting me embellish, and sorry to start off on such a depressing note but I can’t promise the rest will be any less sad. And that’s because science tells us by the year 2050, all the world’s reefs will be under threat and look like the one described above if threats are left unchecked. At the very least what’s left won’t look anything like it does now. And this is all likely to happen in the blink of a geological eye, within our own lifetimes.

As disappointing as it may be, let’s put aside any emotional or aesthetic connection we may have to our colourful underwater cities. There are some very serious survival problems that loom if the phenomenon of ghost reefs transpires. Even though reefs occupy only one fourth of one percent of our oceans, they support 25 percent of all marine life. Reefs are a main building block, a foundation to all kinds of life in our ocean.

By 2050 it’s possible that all coral reefs will be bleached. Image:

Even though reefs occupy only one fourth of one per cent of our oceans, they support 25 per cent of all marine life. Reefs are a main building block, a foundation to all kinds of life in our ocean

Once the reefs are dead, one can only imagine the chain reaction of events. It will send ripple effects up the food chain and significantly change ocean chemistry.  The oceans provide a significant percent of our sustenance and that demand will only increase. It will be near impossible for an unhealthy ocean to meet those needs. And, unfortunately for us humans, what happens in the ocean does not stay in the ocean. Any alteration in ocean chemistry will result in alterations in atmospheric chemistry like oxygen.  It is all connected. You can’t have a healthy Earth without a healthy ocean.

Reefs are often called the rainforests of the ocean because they contain such a huge diversity of life.  It may surprise you to hear that drugs such as AZT (treats HIV/AIDS) and Bryostatin (promising drug for Alzheimer’s) have their roots in coral reefs. Who knows what other lifesaving drugs we may never discover if coral disappears leaving nothing but ghost reefs in its wake?

Ghost reefs

A before and after image of the bleaching in American Samoa. Image:

The state of our corals 

So here’s where we stand now. In the past three decades, 50 per cent of coral reefs have already disappeared. And a new ground breaking study in the journal Science is more sobering news for the future of our reefs.

The study compiled a comprehensive record of 100 reefs in various parts of the world over the past 35 years. What they found was alarming. The incidence of coral bleaching has increased from once every 25 to 30 years, to once every 6 years. Dr. Mark Eakin, one of the authors of this study and coordinator of NOAA Coral Reef Watch, fears that this 6 year window of recovery is not enough to ensure the long term survival of most coral reefs as we know them today.

The study compiled a comprehensive record of 100 reefs in various parts of the world over the past 35 years. What they found was alarming. The incidence of coral bleaching has increased from once every 25 to 30 years, to once every six years

Here’s a quick refresher on bleaching. Healthy corals live in a symbiotic relationship with a particular type of microscopic algae. These algae live in the tissue of the coral and help make food for coral through photosynthesis. Algae gives coral their vibrant colours. But when water temperatures become too warm, corals become stressed and expel their algae partners. As a result the coral weakens and turns white. Although bleaching itself does not kill the coral, it does make the coral more susceptible to disease and easier to kill. It is also the beginning of what is being coined, ghost reefs

You may remember in 2016 a huge bleaching event on the Australian Great Barrier Reef decimated 70 per cent of the northern part of the reef and is said to be the worst event ever recorded. This was due to a ‘Very Strong’ El Nino event warming the western Pacific waters combined with a warming ocean due to climate change. Very Strong El Nino’s typically only occur once every 10 to 15 years. That would give coral reefs at least some decent time to recover. But being that climate change is warming the oceans consistently year to year, bleaching is now common even in non El Nino years.

2017 is a very good example in which another bleaching event took the Great Barrier Reef by storm. There was no El Nino present, but despite that, global ocean temperatures have continued to rise. According to a brand new study by Atmospheric Physics/ Chinese Academy of Science, 2017 registered the warmest global ocean temperatures on record. While temperature records show that the oceans have been warming since the 1970s, oceans are now warming at a faster rate because more than 90 per cent of excess heat due to global warming is being stored in the ocean.

As a result, Atlantic Ocean tropical water temperatures have risen more than 1 degree Fahrenheit since 1970.  One degree may not sound like much, but corals are very sensitive to heat. And water temperatures do not warm evenly so you end up with pockets of water several degrees above normal. If corals endure just a few weeks of water temperatures a couple of degrees above the hottest normal summer average they will start to bleach. That is what is happening 5 times more frequently than it used to.

Make no mistake, the situation is dire Dr. Eakin says ‘We have to throw the kitchen sink at this problem’.

ghost reefs

In the past three decades, 50 per cent of coral reefs have already disappeared. Image:

So what is in the kitchen sink?

Reduce stressors like over fishing, pollution, and habitat destruction. Dramatically upscale local nurseries that grow heat tolerant coral and plant them back in the reefs. Simultaneously, we must use methods like assisted migration; essentially planting corals in areas that are not quite as hot. We must also employ more sophisticated techniques like assisted evolution; the acceleration of naturally occurring evolutionary processes to enhance traits that would be advantageous to coral in a warmer ocean.

All of the above solutions to avoid the acceleration of ghost reefs are a very difficult haul in a growing and demanding world. But even if the above methods are possible to employ on a large scale, Dr. Eakin says it won’t be near enough to save our reefs unless our collective planet figures out how to drastically reduce Greenhouse gas emissions and develops planetary scale solutions to drain the atmosphere of the extra heat trapping gases we have already emitted.

To say that all of this is a gargantuan challenge would be an understatement. But the fate of our reefs, oceans, and possibly the survival of our world depend on the actions our collective societies are willing to take today. We are quickly approaching that ‘do or die’ moment where our reef system will be little more than the ghost reefs alluded to at the start.

In Dr. Eakin’s words: ‘I won’t say I’m optimistic, but I’m not ready to give up hope yet.’ This is a challenge we must meet. Failure is not an option.

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