We knew this was coming. For months, coral reef experts have been loudly, and sometimes mournfully, announcing that much of the treasured Great Barrier Reef has been hit by “severe” coral bleaching, thanks to abnormally warm ocean waters.

Bleaching, though, isn’t the same as coral death. When symbiotic algae leave corals’ bodies and the animals then turn white or “bleach,” they can still bounce back if environmental conditions improve. The Great Barrier Reef has seen major bleaching in some of its sectors – particularly the more isolated, northern reef – and the expectation has long been that this event would result in significant coral death as well.

Now some of the first figures are coming in confirming that. Diving and aerial surveys of 84 reefs by scientists with the ARC Center of Excellence for Coral Reef Studies at James Cook University, in Australia – the same researchers who recently documented at least some bleaching at 93 percent of individual reefs – have found that a striking 35 percent of corals have died in the northern and central sectors of the reef.

The researchers looked at corals from Townsville, Queensland, all the way to New Guinea, said coral expert Terry Hughes.

Fortunately, the southern sector of the reef was largely spared, thanks to the ocean churning and rainfall caused by Tropical Cyclone Winston, which cooled waters in the area, Hughes said. In this region, to the south of Cairns, mortality was only about 5 percent.

But while coral death numbers are far lower to the south, “an average of 35 percent is quite shocking,” Hughes said. “There’s no other natural phenomenon that can cause that level of coral loss at that kind of scale.”

“This coral bleaching is a whole new ballgame,” Hughes said.

There has already been widespread attribution of this record bleaching event to human-caused climate change. One recent statistical analysis gave extremely low odds that the event would have happened by chance in a stable climate. It was caused by record warm March temperatures in the Coral Sea, more than 1.8 degrees Fahrenheit above average.