Fifteen Eighty Four

Academic perspectives from Cambridge University Press


Are the world’s ecosystems about to collapse?

Adrian C. Newton

In 2016, a major environmental crisis occurred: much of Australia’s Great Barrier Reef bleached and died. The Barrier Reef is one of the natural wonders of the world, home to thousands of species, which together create a dazzling array of colour and movement. So to see the Reef suffer in this way is a genuine tragedy, enough to reduce researchers to tears.

This event was described by the world’s media as an example of ecosystem collapse. Environmental degradation caused by human activity is, of course, nothing new. But the idea that ecosystems might suddenly change, or even die, is a novel one. It is only in the past few years that researchers have begun to examine why ecosystems collapse, and what the consequences might be. I decided to summarize what is currently known about the issue, and the result is a book just published by Cambridge University Press, entitled Ecosystem collapse and recovery. This is the first scientific monograph on the topic.

I started by reviewing the theories that might explain collapse. Researchers have developed a wide variety of relevant ideas, the most important of which refer to positive feedback loops. Populations of any organism – including humans – have the potential for exponential growth, which results from just such a loop. Parents produce children, who grow up to produce more children, and so on. Ecosystems are full of such feedbacks, and some of these can produce rapid changes. If you harvest the fish in a coral reef, for example, the seaweed that they normally eat can grow to smother the corals. This then reduces the places where fish can reproduce, which leads to yet more seaweed.

Science progresses by putting theories to the test. So most of the book is devoted to examples of collapse, drawn both from prehistory and the contemporary world. Prehistory provides some remarkable insights into just how profoundly the world has changed in the past. Consider the asteroid strike that wiped out the dinosaurs, just one of five mass extinction events in the fossil record, each of which destroyed most of the world’s species. These events also tell us a great deal about how ecosystems recover after a major disturbance event. The main lesson here is that recovery always takes a lot longer than collapse; in the case of the mass extinction events, recovery took millions of years.

While searching for examples, I encountered many remarkable human stories, such as the colonisation of Australia by boat, more than 50,000 years ago. Or the colonisation of Madagascar by a boatload of Indonesians some 2000 years ago, after they were blown across the Indian Ocean. Or the equally remarkable colonisation of islands in the South Pacific, again involving major seafaring feats. But how did the arrival of people affect the ecosystems of these areas? Did early Australians cause the widespread loss of rain forest, and change the climate of the continent? Was the Sahara desert created by the grazing animals of early pastoralists? Why were the ecosystems of Madagascar and New Zealand permanently transformed by fire?

Inevitably, the best evidence comes from more recent examples, and these form the core of the book. I greatly enjoyed exploring the scientific literature on a wide range of ecosystems including forests, oceans, coral reefs, rivers, lakes, shrublands and savannas. I found surprising references to cannibalistic giants, zombie ideas, topological monsters, theoretical shipwrecks, “aquacalypse now”, “insectageddon”, and ecosystems turning to jelly. Ecologists are not short of colourful phrases to describe the workings of nature. I found that ecosystems can collapse for many reasons, not just because of feedback loops. But the main lesson I learned is the overriding importance of climate change. This has the potential to completely transform all of the world’s ecosystems, as shown by previous mass extinction events, as well as what is now happening to the Barrier Reef. Any of the world’s ecosystems could potentially collapse. Our ability to anticipate and respond to such profound changes depends on our understanding of how ecosystems collapse and recover, so hopefully this book will prove useful in addressing the challenges ahead.

Ecosystem Collapse and Recovery
Author: Adrian C. Newton
Paperback ISBN: 9781108460200
Hardback ISBN: 9781108472739

About The Author

Adrian C. Newton

Adrian C. Newton is Professor of Conservation Ecology in the Centre for Ecology, Environment and Sustainability at Bournemouth University, UK. His research examines human impacts o...

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