October 11, 2019 — The oceans have long been the biggest buffer for humankind’s dangerous greenhouse-gas emissions. Around a quarter of all the carbon dioxide released into the atmosphere since the 1980s—from driving cars, running factories and churning out electricity with fossil fuels—has ended up sunk into the waters. As the planet has warmed from mounting emissions, the oceans warmed first and fastest, absorbing 90% of that excess heat. A report released last month by the UN-based Intergovernmental Panel on Climate Change, the foremost scientific authority on the subject, warned that damage to the oceans is accelerating and may be at the point of irreversibility.
That makes delicate coral reefs around the world something of a leading indicator for the collapse of the ocean ecosystem. Half of all reef systems have already been destroyed, putting a quarter of marine life at risk. Even if global warming is limited to the 1.5 degree Celsius target outlined in the 2016 Paris Agreement—a longshot goal, at the current rate of emissions—the IPCC now concludes that “almost all warm-water coral reefs are projected to suffer significant losses of area and local extinctions.”
In a perverse consequence, lost reefs will leave nearby coastlines even more vulnerable to erosion and storms, as well as from accelerating sea-level rise, which could go up by as much as two feet this century as a result of glacier melt.