The Epidemic No One’s Talking About

For the last few months, the world has been watching the spread of the deadly coronavirus and lives have been upended in the uncertainty of its trajectory. Governments have been mobilizing their responses and businesses have shut down operations. And all the while there’s been another lethal and massive epidemic building. One that has largely escaped our attention.

For the third time in the last five years, the Great Barrier Reef’s corals are predicted to undergo widespread bleaching. On February 16, NOAA’s coral reef watch system issued an alert level of 1, meaning significant bleaching was likely, for the northern and southern reaches of the Great Barrier Reef, a region that spans 1400 miles, roughly the distance from Tijuana to Vancouver. Today, the alert has been raised to the highest level. NOAA’s map of the reef is slathered in blood-red. Severe bleaching and significant mortality are likely.

Coral are animals that live in a symbiotic relationship with algae, like having a photosynthetic tattoo in their tissues. These algae provide as much as 90 percent of the sugar they produce to the coral. When the temperature rises by just a couple degrees for a few weeks, the algae abandon the coral, taking their color with them. This leaves the coral bone-white, or bleached. It also leaves the coral devoid of nutrition and sickened. If the water doesn’t cool and if symbiosis cannot be reestablished, the coral die.

As global temperatures have climbed due to climate change, the ocean has acted as an outsized buffer to the global heat system. It has absorbed 93 percent of the heat held by fossil fuel emissions. Ocean temperatures have already warmed by more than a full degree Celsius. The elevation in baseline temperature has pushed corals closer to their thermal limit for bleaching. Smaller weather perturbations have larger impacts.

In 2016 and 2017, the Great Barrier Reef was hit by back-to-back mass bleachings; the first was set off by the elevated water temperatures of El Nino. Together, they claimed the lives of corals on half the reefs. This year, an extended period of clear skies, weak tides, and lack of cyclones raised the temperature past the tipping point. The death toll remains to be seen.

Coral reefs are the cities of the sea, providing homes for a quarter of all marine species. This bleaching epidemic in the ocean’s greatest metropolis will have consequences not just for the coral but for millions of its marine inhabitants. The toll will extend onto land for the tens of thousands of people who depend on the reef for their food and livelihood, and for all who recognize the Great Barrier Reef as one of the earth’s greatest treasures.

One of the early outcomes of our response to the coronavirus is that with the shuttering of factories and refineries and the disruptions to travel, carbon dioxide emissions dropped 25 percent in China, equivalent to a year of emissions from New York State. While experts predict a rebound once the outbreak passes, this was a critical demonstration. We, as humans, do have the power to make decisions that impact the global health of our planet. Our collective actions do produce results. This problem is not beyond our control.

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