Oceans cover 70 per cent of the Earth’s surface area, forming the largest habitat on the planet. Coastal and shallow-water areas contain some of the world’s most diverse and productive ecosystems, including mangroves, coral reefs and seagrass beds. Coral reefs, referred to as the “tropical rainforests of the ocean”, are estimated to provide benefits worth approximately
US$ 30 billion in goods and services on an annual basis, including income from and resources for tourism, fishing, building materials and coastal protection.1 Although reefs cover only 0.2 per cent of the world’s ocean, they contain about 25 per cent of marine species and are renowned for their biological diversity and high productivity.
In the past two decades, corals reefs have come under siege by a growing global threat: increasing concentrations of carbon dioxide (CO2) in the atmosphere. High CO2 emissions lead to “double trouble” for coral reefs. First, the trapping of heat in the atmosphere leads to ocean warming, which can cause extensive coral bleaching events and mass mortalities. The global devastation of coral reefs from record warming of the sea surface in 1997/98 was the first example of what is likely to occur in the future under a warming climate. Second, high CO2 levels lead to ocean acidification, which reduces the ability of coral reefs to grow and maintain their structure and function. Coral reefs are some of the most species-rich habitats in the world, and they are also among the most sensitive to our current high-emission path.
This brochure summarizes the CO2 threat to coral reefs, the science supporting projections and the solutions that are needed to prevent the loss of one of the world’s natural wonders.
