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The Impact of Climate Change on Coral Reefs

While the allure of the oceans beckons diving enthusiasts, a pressing concern lurks beneath the surface: the profound impact of climate change on coral reefs. Let’s delve into this issue.

The Earth’s delicate thermal balance, influenced by solar radiation, is intricately woven into the atmosphere, oceans, and land. About 30% of incoming solar energy is reflected back into space, with approximately 70% being absorbed, resulting in an average temperature of around 14°C.

We can liken this effect to a greenhouse. Solar radiation enters through the greenhouse glass, heating the air, soil, and plants. Similarly, Earth retains heat through these processes. Without this retention, we would lose heat, and Earth’s temperature would be -18ºC. It’s as if Earth has its natural greenhouse system.

The catch is that on the planet resides a species believed to be very clever, and they have changed the rules of the game. This has consequences: the Earth’s temperature is rising.

Coral reefs, occupying less than 1% of the ocean floor, are critical biodiversity hotspots, providing a home for a quarter of all known marine species. However, climate change wreaks havoc on them.

Continue reading to discover the impact of climate change on coral reefs.

1. The Threat of Climate Change Effects on Coral Reefs

Humans have drastically altered the chemical composition of the Earth’s atmosphere. The combustion of fuels, deforestation, and changes in land use have significantly altered greenhouse gas concentrations, such as carbon dioxide and methane. The result is that our planet has been warming since the industrial era, oceans are acidifying, and coral reefs are paying the price.

The impact of climate change on coral reefs is palpable. As early as 2009, the Global Coral Reef Monitoring Network  reported a troubling 14% loss of coral.

A special report from the Intergovernmental Panel on Climate Change (IPCC) in 2018 predicted that coral reefs could decline significantly, between 70% and 90%, if global air temperatures rise by 1.5°C (2.7°F). We have already reached a 1.1°C (2.0°F) increase. Yes, the forecasts are alarming.

Despite the challenges, some corals show remarkable adaptations to survive in adverse environments. In the tropical eastern Pacific, for example, some reefs are becoming more heat-resistant by changing the algae they host. Scientists are identifying these resilient corals and working on methods to cultivate and reintroduce them into the ocean. Still, there is hope.

impact of climate change on coral reefs (3)

2. Why Climate Change Affects Coral Reefs


2.1. The Nature of Corals

To comprehend the impact of climate change on coral reefs, it is crucial to understand the intricate life of corals. Their growth is inherently linked to factors such as relatively warm shallow waters, salinities between 27‰ and 40‰, sunlight, high nutrient content from oceanic tides, and a firm substrate for them to thrive.

The external skeleton of the coral, called the exoskeleton, acts as protection for the polyp. A coral is composed of millions of these polyps or mouths. The polyp extracts calcium carbonate from seawater and deposits it around to form its skeleton, providing support. Polyps can live for hundreds or even thousands of years. This process is called calcification.

Although corals are translucent, their color comes from a symbiotic relationship with single-celled algae called zooxanthellae, living inside the polyp tissues. This symbiosis provides essential nutrients for coral growth and reproduction. In turn, algae generate oxygen and help the coral eliminate waste. In this partnership, the coral protects zooxanthellae and offers an environment for them to obtain nutrients.

2.2. Effects of Climate Change on Coral Reefs

The repercussions of climate change on coral reefs manifest in various ways.

Acidification As divers, we know our oceans are a treasure trove of beauty and life. However, the use of fossil fuels is leaving its mark because the ocean we love absorbs a significant portion of greenhouse gases.

High levels of carbon dioxide are changing the water’s chemistry, lowering its pH and making it more acidic. This acidification reduces the amount of carbonate ions necessary for coral skeletons to form, causing difficulties in building their skeletons.

Thermal Stress Ove Hoegh-Guldberg, a marine studies expert at the University of Queensland in Australia, reveals that these beautiful ecosystems are sensitive to small temperature changes. When the marine thermometer rises, corals can become stressed and undergo bleaching. This effect of climate change on corals is famous, as it has occurred massively in some areas of the Great Barrier Reef. It happens when stressed corals expel those small companions we introduced earlier, the zooxanthellae, and become bare, showing their white skeletons. This disease, though curable, can also lead to their death.

Hurricanes and Sediments With rising sea temperatures, hurricane activity has increased. The strong waves and sediments deposited by these storms damage and suffocate our coral friends.

Rising Sea Level The rising sea level can bring more sediments, threatening life on reefs near the coast.

3. How Do We Halt the Impact of Climate Change on Coral Reefs?

Amid growing concern about the impact of climate change on coral reefs, governments of coastal and tropical countries are exploring innovative strategies to preserve the health of these crucial ecosystems.

According to collected data, reducing the effects of climate change and human activities emerges as the only way to ensure the survival of these reefs.

The proposed actions to achieve this are:

  1. Paris Agreement Compliance: Limiting the increase in global temperature to less than 2°C above pre-industrial levels, in line with the Paris Agreement, is presented as the only opportunity for the global survival of coral reefs. Full compliance with this agreement would lead to a decrease in atmospheric carbon concentrations, improving conditions for reef survival.
  2. Economic Systems Transformation: There is a highlighted need for a transformation in economic systems toward circular economic practices. This would include the implementation of the United Nations’ Sustainable Development Goals (SDGs), especially SDG 8 (inclusive and sustainable economic growth) and SDG 12 (sustainable consumption and production patterns).
  3. Recognition of Reefs as Assets: A shift in the economic perception of coral reefs is proposed, advocating for treating their preservation as a long-term asset. This would involve continuous investments in their conservation and restoration.
  4. Investments in Research: The importance of investments in research is emphasized, especially in areas like the genetic selection and genomics of heat-resistant corals. This research aims to develop corals capable of withstanding rising global temperatures.

Countries like Mexico, through the Ministry of Environment and Natural Resources (SEMARNAT), are increasingly joining monitoring projects, such as Global Fishing Watch, providing real-time tracking of global fishing, and collaborating with actions like “Project Eyes on the Sea” or even NASA for satellite monitoring of ocean health.

4. Divers Called to Action to Halt Climate Change Effects on Coral Reefs

Governments, environmental agencies, and the diving community are more united than ever in a collective effort to mitigate the effects of climate change on coral reefs. Good examples of this are the “Go Green” projects by Dressel Divers and the “Wave of Change” initiative by Iberostar.

For the vibrant community of divers who enjoy their favorite sport, each dive is an opportunity to take action and admire the beauty and fragility of these underwater wonders, emphasizing the responsibility to protect them for future generations.

A notable example of this is Dressel Divers’ “Reef and Wreck” excursion, where divers can visit a coral nursery with which we have collaborated. FUNDEMAR is the foundation responsible for this program to limit the impact of climate change on coral reefs, focusing on the recovery of Acropora cervicornis corals.

The colonies of stag-horn corals, as they are commonly known, experienced a reduction of around 97% in the 1980s. This decline was primarily attributed to the disease that causes coral bleaching, along with factors such as hurricanes, storms, the activity of coral-feeding organisms, thermal stress, rising sea levels, and pollution.

Today, this program is a total success and serves as an example of how human action can help curb the impact of climate change on coral reefs. The initiative continues to grow day by day, thanks to the unwavering support from the tourism sector and the efforts of the divers who implemented it. Moreover, each dive center is assigned a nursery that is cared for and maintained. Would you like to come and see ours? Contact us!