Increases in ocean temperature cause corals to expel the tiny algae that nourish them and give them their vivid colours.

Each person will download a set of variables, such as ocean temperature.

But that graph combines land and ocean temperature.

The tag was the most important monitor: scientists can plot the data against ocean temperature charts to trace its route at sea.

The ocean temperature was above normal in most areas, prompting mass bleaching of many coral reefs.