What’s Happening to our Coral Reefs?

Over labor day weekend, right before I launched this blog, I had the luxury of visiting my boyfriend in Hawaii. While I was there, we went on a hike. The view was gorgeous. Deeply green mountains with lush ridges swept down toward an ocean of bright blues. In anticipation of the blog’s launch, I had recently watched the documentary Chasing Coral (check out my review here!). I turned to my boyfriend and said, “We’re killing coral reefs, you know. Just eliminating them.”

He didn’t seem very concerned.

So I pushed. “But it’ll be lost! It’ll just disappear and be this memory we have, like the Jurassic period. Coral reefs will be this stunning, lost thing that future generations can barely conceptualize.”

He shrugged. “And something beautiful will replace it. There are bigger problems in the world than dying coral.”

This led me to ask myself: is he right? If we lose coral reefs, are we simply losing one iteration of beauty and magnificence? An iteration that will be replaced with something that can thrive in our heating climate? Possibly. And it’s possible that there are more important things to salvage or preserve as the environment changes and evolves. At a minimum, reminding ourselves of past and future beauty is a way to keep these changes in perspective. The earth will adapt to the changes, as it has for thousands and millions of years before.

However. If we’re going to decide that we can do without coral, that coral reefs are to be chalked up as collateral damage to this rapidly heating planet, then we have a duty to be informed. We should know what it is we are losing. We should know what we’re losing and why we’re losing it because 1) there may be portions of it worth saving and 2) if we’re going to let the reefs die, then that should be an educated decision.

This week’s post will first explore the specific effects of climate change on the reefs, then move into a discussion of why reef loss is a relevant concern, and finally end with a list of ways we can help preserve the reefs of our magnificent oceans.

What’s Happening? Rising Ocean Temperatures

history of ocean temperature

One factor that makes it tricky to monitor and fully understand the rate of our current climate change is a lack of holistic data. Since we are looking at a global phenomenon, it would be idea if we had centuries, or even millennium, of global data with which to compare current trends. Of course, this is a luxury we don’t have. Most data concerning weather patterns and global temperatures only go back to the late 19th century, which doesn’t give us a large window of comparison.

Source: NOAA, 2016 http://www.epa.gov/climate-indicators

Taking a look at the above chart, we can still observe a clear warming trend. How does this compare in speed to previous shifts in our earth’s climate? While it’s impossible to do anything more than speculate about how the last 160 years compares to other changes in the earth’s history, we do know that the past 40 years have brought an alarming rate of change in both our sea and air temperatures1.

Because our planet’s surface is 2/3 water, the oceans are absorbing much of the added heat, which saves us from drowning in our own sweat. Because there’s so much water, we see a “mere” increase of 1 degree fahrenheit in the last century. But this change can have a devastating effect on life under the sea.

coral bleaching

Picture a coral reef. What do you see? Tropical fish darting in and out of anemone, rocks, and colorful, waving coral. The coral comes in fans, sponges, and tubes in all manner of shapes and sizes. The range of color is like none other found on our planet.

Photo credit: The Ocean Agency / Catlin Seaview Survey

These colors disappear when ocean temperatures rise. When the animal is put under stress, algae living in the coral leaves, stripping the animal of color. Without the algae – with which corals have a symbiotic relationship – the animal is vulnerable to disease and largely unable to get the nutrition it needs to survive. It can survive without algae for a time, but unless conditions improve and the algae returns, the animal will die.

What’s Happening? Changes in Storm Pattern

typhoons and hurricanes

Photo by Siednji Leon on Unsplash

According to the National Climate Assessment published in 20142, the intensity, frequency, and duration of North American hurricanes have been increasing since the early 1980s, and they’re expected to continue to grow in severity. Additionally, the frequency of category 4 and 5 hurricanes has gone up. In fact, as of 1970, the average number of category 4 and 5 hurricane-type storms around the world was roughly 10 per year. As of 2005, when Hurricane Katrina decimated New Orleans, LA, the average was up to 18 per year3.

While there are a number of factors that play into the quantity and size of hurricanes in the Atlantic – as well as typhoons in the Pacific – higher ocean surface temperatures are strongly associated with more devastating hurricane and typhoon seasons. While scientists are still working to fully understand our impact on the weather, as well as the blend of factors that create brutal hurricane/typhoon seasons, we do know that this increase in storm activity causes havoc below the ocean’s surface.

reef destruction

While tropical storms and category 1 hurricanes can help reefs by clearing out dead plant and animal matter, stronger storms can wreak havoc on our reefs. As would be expected, the more powerful the storm, the higher the odds that it will wipe out entire reefs. While some of the reefs do eventually come back, an increased number of category 4 and 5 hurricanes more or less assures that reefs will have fewer gaps between beatings, giving them less time to recover.

Need to see the destruction for yourself? Luckily for conservation activists, modern technology has been bringing the ocean more and more into the public eye over the past few decades. A quick search for “hurricane effects on coral reefs” will give you multiple stories, images, and videos to look through.

murky waters and low light

Though it varies from region to region, there is little doubt that part of climate change is the fluctuation of rainfall patterns and precipitation rates. While this is in part related to an increased number of hurricanes and typhoons, increased rainfall of less monumental proportions can still affect our coral reefs.

Consider the waters of the tropics. They’re known for being crystal clear and almost surreally blue. But when precipitation levels rise, the waters around reefs can become murkier or cloudier than usual. This makes it harder for the coral to receive the sunlight and nutrition that are key for their survival. This inhibits the animal’s growth and can result in weaker coral, which is more susceptible to disease or destruction.

What’s Happening? Reduced pH Levels

co2 increase

This next issue is a simple chain of cause and effect. Higher levels of carbon dioxide in the atmosphere has led to higher levels of CO2 in the ocean. In turn, this increase in carbon dioxide lowers the pH levels of the oceans, leaving them more acidic. The below graphs show the correlation between increased CO2 and decreased pH in various parts of the ocean.

Source: Environmental Protection Agency http://www.epa.gov/climate-indicators

coral growth rates and integrity

When coral skeletons grow, they grow both upward and outward – much like a tree. They reach up toward the sunlight, and their skeletons increase in thickness and density, leaving them sturdier. Lower pH levels in the ocean affect the density of coral skeletons, which in turn leave them more susceptible to breakage.

Photo by Marek Okon on Unsplash

A 2018 study conducted by the Woods Hole Oceanographic Institution anticipates that these negative effects will be greatest in the Indo-Pacific region4, where they expect coral density to decrease by as much as 20% by 2100. Even in the regions anticipated to be less affected, including coral reefs in Hawaii, the Caribbean, and the Red Sea, density is expected to decrease by 10%. That’s solely taking ocean acidity into account. Any other factors that affect coral density will have additional consequences.

Why Care? Food Sources

So why should we care about any of this? My argument about beauty didn’t seem to be particularly convincing to my boyfriend, but surely there are other reasons the coral reefs are important to humans.

Indeed! There are a great number of reasons. A major one is food supply. As members of the English-speaking world, and more specifically as Americans, it’s easy to forget that decisions we make or the consumption patterns we participate in can have an affect on much less fortunate members of our planet (For example, calling for veganism or even vegetarianism comes from a place of privilege, as it means we are able to be selective about what we do or don’t eat).

Map of the Coral Triangle

In this particular case, I would not be largely affected by not being able to eat fish from coral reefs, as I barely eat any fish due to their cost in my area. But the fish of coral reefs provide the primary meat protein for over one billion people, most of whom live in developing countries. These fish compose a necessary part of their diet, from both a nutritional and caloric standpoint. Additionally, fishing activity from coral reefs make up a $6.8 billion dollar industry, and in the Coral Triangle, there are an estimated 15 million small-scale fishers5. Who are we to decide that their source of income isn’t worth saving?

Some might push back against the above argument, pointing out the dangers of overfishing and claiming that my argument goes against the ideas of conservation. But I have good news! Small, community-run fisheries are actually much better at sustaining the fish population than large corporations or, in some cases, federal regulations6. The people who most depend on these fish as part of their diets or incomes are the very people who understand the importance of keeping the fish population healthy (shocker).

Why Care? Medicinal Properties

Something I hadn’t realized about coral reefs until watching the documentary, Chasing Coral, was their contribution to modern medicine. So far, using chemical compounds from the plants and animals found in coral reefs, scientists have contributed to remedies for cardiovascular diseases, ulcers, leukemia, lymphoma, and skin cancer7. Additionally, there are chemical compounds found in these environments that help with muscle relaxation and inflammation reduction.

Photo by Ani Kolleshi on Unsplash

It would be an act of incredible arrogance to assume that we have gotten all the scientific use we can from these ecosystems, and this is one more reason that the biodiversity of life in the reefs is worth saving. Maybe that doesn’t mean we can save all the reefs in the ocean, but perhaps we can fund endeavors to harvest samples and recreate reefs in currated environments. If there are chemical compounds in these plants and animals that could cure cancer and boost the quality of human life, shouldn’t we do everything within reason to preserve them?

Why Care? Coastal Protection

What does the “barrier” in Great Barrier Reef mean? Exactly what it sounds like, but it’s a fact that can be easy to forget, because it’s one we take for granted. Barrier reefs help protect our homes and our cities from the devastation of tropical storms, hurricanes, and typhoons. In fact, at least 200 million people are directly dependant on reefs to protect their lives, their homes, and their communities from large waves and storm surges8. (Quick aside – The source I got this info from, WWF’s Living Planet Report, is an extensive, easy to read report about the state of various ecosystems and their immediate effects on humanity. Well worth a read, or at least a skim!)

When talking about reef loss, we begin to deal in the realm of hypotheticals. What will happen to small coastal villages if these barriers are gone? What risk will be posed to coastal cities in Queensland, Australia, which currently benefit from the protection of the Great Barrier Reef? Even if we’re at a point of no return, or the climate continues to warm despite our best efforts, we need to be aware of the potential consequences of losing reefs. We need to begin planning for the impending complications and problems, because keeping 200 million people safe from destructive waves seems like it should be a priority.

How Can We Help?

Reduce co2 output

Photo by VanveenJF on Unsplash

Many of the issues immediately facing our coral reefs are correlated with global warming. As the oceans heat up, coral suffers, and as the pH level lowers, coral becomes even more vulnerable to harsh conditions caused by the heat. If, if, we can possibly reduce the amount of greenhouse gases in the atmosphere and slow the rapid warming of the earth, the ocean would be the first place to feel the effects. Our oceans absorb 90% of the additional heat trapped by greenhouse gases, and so they would experience the most relief if we find a way to reduce CO2 emissions in a meaningful way.

In my article, “Reducing Our Greenhouse Gases,” I detail some ways in which we, as well as society as a whole, can work to reduce the amount of carbon dioxide we’re pumping into the air. There are those who will tell you humans can’t do anything, or that we certainly can’t do enough to change the rate of climate change. There are also people who claim that we’ve done irreversible damage. But I do not believe this should dissuade us from making better choices. There are plenty of unseen consequences that could be coming our way, and reducing the amount of toxins we’re pumping into the air will never be a bad thing.

be careful with chemicals

“All drains lead to the ocean.” Technically untrue as it relates to fish burials, but a good sentiment to bear in mind. The chemicals you flush down the drain, the chemicals you clean your showers and sinks with, and the chemicals you use in your backyard all end up in a water source, and those sources are linked to the ocean. Chemical runoff isn’t just a corporate level problem. Individuals also need to be mindful about what they’re letting spill onto the earth and into the water.

The chemicals we send into the oceans can affect the health of coral reefs and have an impact on the pH level of the water. The altered pH and composition of the water then has a detrimental effect on coral growth and the animals’ immune systems.

Photo by chuttersnap on Unsplash

In my post, “Clean Green: 5 Tips for Eco-Friendly Housework,” I introduce a variety of natural, gentler cleaning supplies. Making your own cleaning supplies is another great way to reduce the amount of harsh chemicals that go sliding into the water. Additionally, if you have a garden or spend a lot of time manicuring your lawn, be mindful of the sprays and fertilizers you use! Perhaps another post for another week…

practice reef ETIQUETTE

Realistically, many people won’t ever get up close and personal with a coral reef. If you do get the chance to swim next to one of these beauties, though, treat it like the wildlife it is! Any time we’re immersing ourselves in nature, it’s important to abide by the rules that keep the plants, animals, and ourselves safe. Since the environment and harsh weather conditions are already affecting the sturdiness of coral, we don’t need to add to this damage with our carelessness.


Below are a few basic rules I found for scuba divers and snorkelers who find themself hovering above and around these underwater beauties. These rules are all listed and elaborated upon on the Florida Keys National Marine Sanctuary’s website9.

  • Avoid contact with the reef
  • Never rest or stand directly on coral
  • Maintain proper buoyancy
  • Make sure all your equipment is secure
  • Maintain a comfortable distance from the reef
  • Do not touch, handle, feed, or ride the marine life (Yes. This was the exact wording. Turtles are not your underwater horseback ride)
  • Do not collect souvenirs from the reef

support coral farms

Coral Vita is one company that’s working hard to sustain the earth’s supply of coral. Their mission statement? “By growing diverse and resilient corals and transplanting them into threatened reefs, we help preserve the ocean’s biodiversity while protecting the health and prosperity of communities, nations, and industries, and nations that depend on reefs for coastal protection, food, and income.”10

In addition to maintaining their own farms, they also supply coral to smaller, local farms. They work with governments and local communities in order to raise awareness, generate eco-tourism, and promote the importance of coral to our lifestyle and our planet. Though I wasn’t able to find details on their website, they claim that opportunties exist to help sponsor their restoration and farming projects.

This is just one example of a company that’s working to preserve and sustain the world’s supply of coral. Check out their website for more information on their mission and coral farming in general!

This post is the second in my “What’s Happening?” series, which documents the effects of pollution, climate change, and poor business practices on various ecosystems of our planet. Check out the first in the series, “What’s Happening to the Amazon?” The third post in this series will likely appear in January, and I would love to hear your feedback on which environment you’re eager to learn about!

Follow me on Twitter: @AbbyHarrison33 @Blog_D2Earth


1Cook, John. “Comparing Past Climate Change to Recent Global Warming” https://skepticalscience.com/global-warming-1860-1880-and-1910-1940.htm

2“Changes in Hurricanes” https://nca2014.globalchange.gov/report/our-changing-climate/changes-hurricanes

3“Number of Category 4 and 5 Hurricanes has Doubled” https://www.nsf.gov/news/news_summ.jsp?cntn_id=104428

4“Scientists Pinpoint How Ocean Acidification Weakens Coral Skeletons” https://www.whoi.edu/press-room/news-release/scientists-identify-how-ocean-acidification-weakens-coral-skeletons/

5“Importance of Reef Fisheries” http://reefresilience.org/coral-reef-fisheries-module/coral-reef-fisheries/importance-of-reef-fisheries/

6“Community Power Can Rescue Failing Fishing Stocks” https://phys.org/news/2013-04-power-fish-stocks.html

7“Why Care About Reefs? Medicine” https://coral.org/coral-reefs-101/why-care-about-reefs/medicine/

8“WWF Living Planet Report” https://c402277.ssl.cf1.rackcdn.com/publications/1187/files/original/LPR2018_Full_Report_Spreads.pdf#page=29

9“Reef Etiquette” https://floridakeys.noaa.gov/onthewater/etiquette_text.html

10Coral Vita https://www.coralvita.co/concerned-citizens-and-communities

11National Ocean Service “How Does Climate Change Affect Coral Reefs?” https://oceanservice.noaa.gov/facts/coralreef-climate.html

12Zoon, Jennifer “Testing the Waters” https://www.smithsonianmag.com/blogs/national-zoo/2019/10/23/testing-waters-coral-nurseries-and-climate-change/

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