Roberts revels in the details of life on a coral reef. A mantis shrimp, for instance, has “a carapace of mottled green edged with a thin red line like the piping on an iced cake”. Its eyes, “frosted glass balls on blue stalks, marked with a horizontal line like the slot of a helmet visor”, give it “an almost supernatural power” to see linear and circularly polarised light. This book also addresses the major questions regarding human responsibility and possibilities for change. We live at what is probably the zenith of coral reef evolution in hundreds of millions of years in terms of their diversity and productivity, but human action might bring this all to an end within a few generations: “It is an extraordinary position that I still grapple with daily to understand.”
Roberts and his colleagues rake through the ashes of a desolate future, looking for embers of hope. Some corals have been found that can live in acidified water, and perhaps natural selection will throw up heat-tolerant corals, although the adaptation might be slower than the oceans’ rate of warming. Perhaps there will be less diverse, but more resilient reefs, like the hardier corals Roberts encountered in the Arabian Gulf.