Coral of an unknown provenance.

Optimists look at the Great Barrier Reef and see it half-full of coral.

Australia’s Great Barrier Reef has lost more than half its coral cover since 1985, according to a new study published Monday. The loss has been spurred by a combination of factors including hurricanes, coral-eating starfish and coral bleaching.

Grist relies on the support of generous readers like you. Donate today to keep our climate news free. All donations matched!

The paper, in the Proceedings of the National Academy of Sciences, is the most comprehensive survey of a reef system over such a long period. The researchers from the Australian Institute of Marine Science found that reef cover fell from 28 percent to 13.8 percent over the past 27 years, with two-thirds of the decline occurring since 1998.

Grist thanks its sponsors. Become one.

Pessimists are in the corner, sobbing and/or catatonic.

Hat-tip: Steve Silberman.