Top level statistics and info
- Coral reefs are called “the rainforests of the sea”: they cover just 0.1% of the ocean surface yet they are the home to over 25% of all marine species.
- Besides supporting biodiversity, coral reefs have a variety of other benefits, including their ability to buffer shorelines against 97% of the energy in waves.
- Over 500 million people directly rely on coral reefs for their livelihoods, either as a source of food, economic activity from tourism, etc.
- The economic value of healthy coral reefs have varied estimates, from tens of billions of dollars on the one end, to $6 trillion on the other
- Coral reefs are under immense pressure from the combined threats of habitat destruction, pollution, and climate change. It is estimated that by 2050, 90% of coral reefs might disappear unless we act.
The importance of coral reefs
A coral reef is an underwater ecosystem made up of corals. Preferring shallow, warm, nutrient sparse waters, they cover only 0.1% of the ocean surface, an area roughly half the size of France. Despite this, coral reefs are among the most diverse ecosystems on the planet, supporting more than 25% of all named species of marine life; including more than 4,000 types of fish. Over 500 million people rely directly on coral reefs for their livelihoods, through a combination of food security, tourism income, and even coastline protection. Estimated more broadly, the number of people that benefit in some way from coral reefs is over 1 billion. Coral reefs are also considered ‘the medicine chests of the 21st century’, with half of all new cancer drug research focusing on marine organisms. The value of coral reefs globally are estimated as high as 6 trillion dollars.
The challenge facing coral reefs
Coral reefs are “at the nexus of our triple planetary crises" of biodiversity breakdown, climate emergency, and rampant pollution. A lot of reefs have suffered from habitat destruction as humans have built out ports and shipping lanes. Other reefs have degraded as surrounding areas have been overfished, upsetting delicate food chains. Many reefs are also polluted from sources as varied as fertilizer runoffs to chemicals in sunscreen.
Climate change is also a persistent threat, for two main reasons. As the planet warms, so does the oceans, which causes stress to corals. At the same time, CO2 concentrations in the water increases, turning the water more acidic. Coral reefs rely on a symbiotic relationship between the corals themselves and microscopic algae called zooxanthellae living within them. These algae are the corals main source of food, and they even provide corals with their characteristic vibrant colors. Warmer, more acidic water might cause the coral to expel the algae, leading to ‘coral bleaching.’ While bleaching don’t kill corals outright, a reef might struggle to rebound after a bleaching event. Coral bleaching events are becoming more common as the world continues to warm.