An expansive new report on the state of the planet's coral reefs contains reason to shudder. It found that in the 10 years starting in 2009, about 14% of the world's coral reefs were lost, the New York Times reports. Report editor David Obura puts that in perspective: "In finance, we worry about half-percent declines and half-percent changes in employment and interest rates." The trajectory is particularly bothersome, with another research scientist involved with the report saying, "Since 2009, it's a constant decline at the global level."
Pollution, fishing, and construction play a role, but bleaching caused by warming seas is the biggest villain. The bleaching happens when rising ocean temps cause corals to kick out algae, per the Washington Post. The corals can then turn white and eventually starve to death. The first such global event was in 1998, killing 8% of the world's coral, but many of the reefs were able to heal. That doesn't seem to be happening as often, scientists say. Some of the 900 or so coral species seem to be able to handle the heat and acidification, but those types grow more slowly.
The Post sees that past rebound as a glimmer of hope, noting "the underwater ecosystems have bounced back in the past when they faced less pressure." That means, per the scientists, that it's imperative to act soon to cut greenhouse gas emissions that contribute to global warming. And there's a financial imperative for doing so: The report puts the benefits of coral at $2.7 trillion per year—including supporting fish that are harvested and eaten, protecting coastlines from storm damage, and generating tourism dollars.
The UN, which supported the study by the International Coral Reef Initiative, called the assessment the most complete ever; it included data from 73 countries over 40 years and measured damage to reefs in places including South Asia, Australia, and the Pacific. And if anything, the findings might be overly focused on healthy reefs, an expert not involved in the work said, suggesting that researchers don't always engage with or stick with sites that are "degraded," potentially obscuring what is happening in those locations. (Read more coral reefs stories.)