Report Details Triple Threat to Coral Reefs

In a new report about how the world’s coral reefs face “the combined threats of climate change, pollution, and overfishing”—endangering the future of marine biodiversity—a London-based nonprofit calls for greater global efforts to end the climate crisis and ensure the survival of these vital underwater ecosystems. The report, entitled Marine Havens Under Threat: The impacts of the climate crisis on tropical coral reefs and the communities that rely on them (pdf), was published Wednesday by the Environmental Justice Foundation (EJF).

EJF warns that because of human activities that heat and pollute the planet, coral reefs “are under imminent risk of destruction,” pointing to a recent estimate from the United Nations’ Intergovernmental Panel on Climate Change (IPCC) that global warming of 2°C could kill 99% of all corals.

The ocean, which covers more than 70% of the planet, “has taken up between 20–30% of total anthropogenic CO2 emissions since the 1980s causing further ocean acidification,” according to an IPCC special report from last year. The lead author of a study published last week said that “the amount of heat we have put in the world’s oceans in the past 25 years equals to 3.6 billion Hiroshima atom-bomb explosions.”

Some scientists refer to three key climate-related pressures on the marine environment—warming, acidification, and oxygen loss—as the “deadly trio.” Experts also warn that human-caused global heating leads to sea level rise and certain extreme weather events becoming more frequent and intense.

“As the global temperature rises, reefs will be put at risk from warming oceans, higher frequency cyclones, increased precipitation, sea level rise, rising acidification, and changing ocean circulation,” the EJF report says. “These factors alter the delicate balance of conditions necessary for tropical coral reefs to function, causing bleaching and destruction of reefs. In many cases, this damage is irreversible.”

Marine heatwaves, which experts warn will become more common as humans continue to heat the planet, have led to major coral bleaching events around the world in recent years. A study from 2018 concluded that the Great Barrier Reef off the coast of Australia, the world’s largest coral system, was “forever damaged” following back-to-back bleaching events that collectively killed half of the corals.

Bleaching refers to when stressors such as warm water and pollution lead coral to expel algae, its main food source, and turn white. Bleached coral faces a greater risk of disease and death but can recover if surrounding conditions improve. Last year, a study about severe marine heatwaves heightened alarm about the future; researchers found cases where “the water temperatures are so warm that the coral animal doesn’t bleach—in terms of a loss of its symbiosis—the animal dies and its underlying skeleton is all that remains.”

EJF, in its new report and an accompanying video, highlighted the consequences of coral bleaching and death events for both marine wildlife and humans.

“Tropical coral reefs support an estimated quarter of all marine species: hundreds of thousands of animal and plant species, who rely on the reef for food, shelter, and a safe place to live and reproduce,” the report says. “These complex ecosystems include hard and soft corals, sponges, crustaceans, molluscs, fish, sea turtles, sharks, dolphins, and much more—including ‘foundation’ and ‘keystone’ species such as corals and sea turtles.”

The report also spotlights a U.N. estimate that at least 275 million people rely on healthy coral reefs as an “essential source of food, employment, income, and storm protection for coastal communities.”

In terms of the economic value of coral reefs, EJF puts tourism and recreation at $9.6 billion, coastal protection at $9 billion, fisheries at $5.7 billion, and wildlife at $5.5 billion. Directly below the economic figures, the report features “a note of caution: Valuing biodiversity in this way is of course subjective, how do we put a value on a species’ intrinsic right to exist?”

To combat the triple threat that coral reefs are facing, EJF puts forth recommendations to end the climate crisis: implement the Paris agreement and fully transition all industrial economies to zero carbon by 2030, create a European Union inter-agency taskforce “to drive a more effective, integrated” global response, and establish a U.N. special rapporteur on human rights, economic well-being, and climate change.

EJF presents another set of specific recommendations to ensure that remaining corals “survive the climate change that is irreversible,” calling for an end to illegal and unsustainable fishing as well as pollution that harms coral, including agricultural runoff, sewage, and plastic. The group also calls for expanding marine protected areas to cover at least 30% of the ocean, and assuring that such zones have “clear restrictions and effective conservation aims.”

“In all deliberations and future negotiations,” the report adds, “all stakeholders must be included, with special reference to local communities.”

Acknowledging that coral reefs “are not only a vital source of food and income for millions of people” but also “home to a vast diversity of irreplaceable wildlife,” EJF executive director Steve Trent warned Wednesday that “failure to act now to protect them will cause environmental ruin and with it a human tragedy.”