Author: James Bradley. Published by Hamish Hamilton in 2024
Review by Graham Kelly of NPA’s Environmental Book Group
Bradley is a Sydney writer of fiction and science non-fiction and is also a prize-winning critic. He brings his vast research and expressive skills to this wide-ranging set of views of the ocean. The book describes its multiple layers and ecology, the nature and lives of its inhabitants, and major contemporary topics relating to their health and future. Historical narratives are frequently used to explain how we have arrived at current situations and to inform the future. Current research and activities aimed at mitigating the effects of adverse future changes are often included to express hope for the future.
The author begins with a history of water and oceans on earth from its formation to the current era. Human activities described include the movements of Homo erectus from Africa, ancient Mediterranean and Pacific journeys, European expansion and colonisation, a history of swimming, and Australian indigenous cultural memories of changing water levels in the transitions from the last ice age.
The author then describes aspects of life experienced by those who live in the ocean. The Diel migration of myriad species from the mesopelagic zone (200m to 1km deep) to nearer the surface every night to feed is estimated at possibly around 10 billion tonnes biomass, certainly the “largest migration on earth”. The use of trackers has informed us about many longer migrations, including birds, fish, turtles and whales. Sound travels faster and more efficiently though water than air. In one experiment low frequency sounds from underwater loudspeakers were detected 17,000km away, in a different ocean. Sources of noise in the ocean include fish (the largest source), crustaceans, sea urchins, whales, dolphins and diel migration. Its purpose includes feeding, communication and social behaviour. Fish have capabilities not appreciated by most humans, notable examples being the communicative gestures of coral trout, collaborative hunting between grouper fish and moray eels, and the astonishing memory and cognitive abilities of cleaner wrasse in their management of “clients”.
Below the mesopelagic zone the only natural source of light is bioluminescence, and all life is animal as photosynthesis is not possible. There is life at all lower levels, feeding from dead animals and plants drifting from above to the ocean floor (“marine snow”). The ocean floor level has fish, octopus, brittle stars, starfish, crustaceans, worms and other invertebrates.
The remainder of the book covers the more familiar impacts of industrialisation and human induced climate change on the ocean environment. Topics include the growth and impact of shipping, pollution from plastics and radioactive materials, coral bleaching and overfishing. Plastics are widely visible and likely ubiquitous on the ocean floor. The author expresses significant concerns about deep sea mining impacts on the ocean floor ecosystem, about which we have much to learn. Since 2015 there have been highly statistically significant reductions in the extent of sea ice around Antarctica. Sea ice slows the flow of ice from glaciers to the sea and stabilises their structure. Based on known past history of the West Antarctic Ice Sheet, recent observations of the giant Thwaites Glacier and the sea ice shelf it flows into, the author conjectures a “tipping point” has been reached, leading to likely collapse of that part of the West Antarctic ice sheet quite soon. This would result in a 0.65m sea level rise over a modest time period. More tipping points may follow.
Members of the book club recommend this book for the range and originality of the topics covered, the depth of research as well as its engaging and at times passionate writing style.