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IN JUNE 2016, scientists from the University of Queensland confirmed what had been feared for some time: the Bramble Cay mosaic-tailed rat was no more. This small rodent eked out a lonely existence on Bramble Cay, a tiny dot of land at the northern end of the Great Barrier Reef. When Europeans first landed in 1845, the place was teeming with them. But frequent inundations caused by rising sea level made life increasingly precarious and the creature is now literally a drowned rat.

This is in many ways a familiar story. A once-thriving population, endemic to a small island, wiped out by human activity. But it is also a first. The Bramble Cay mosaic-tailed rat is the only species that we know for sure was driven extinct by climate change.

We are thus in an era where two great environmental anxieties – climate change and biodiversity loss – are converging. Biologists expect many more species to go the way of the rat. If we are not already in the midst of the sixth mass extinction, we soon will be.


Or will we? There’s no doubt that large animals are in trouble. But in recent years, attention has turned to the lesser known inhabitants of our ecosystems – insects, molluscs, fungi, mosses and so on. There have been warnings of an “insectageddon”, and of life approaching a “tipping point”. But in fact, as our cover feature explains, the evidence for all this is limited. There is not a lot of data and what little there is presents a mixed picture. In many places, biodiversity is actually increasing (see “Biodiversity in crisis: How close to the brink is life on Earth?”).

Nobody in conservation biology doubts the reality of the crisis. But there is a higher hunch-to-data ratio in that claim than they might want to admit.

“Biodiversity decline is the canary in the coal mine for a broader malaise that will come back to haunt us”

Pointing this out is not to undermine their work, but to lobby for more of it. To properly understand what is happening to life on Earth and work out what, if anything, can be done, we need a lot more data. Gathering it is difficult and expensive, and it is the sort of science that gets cut when budgets get trimmed. Biodiversity is often seen as a second-order problem, a luxury item that we can deal with once we have nailed more pressing problems like hunger, war, overpopulation and climate.

That is a mistake. Biodiversity decline is the canary in the coal mine for a broader malaise that will eventually come back to haunt us. If we don’t care about it for its own sake, we should care about it for selfish reasons. In cosmic terms, Earth is Bramble Cay, a tiny habitable dot in an otherwise hostile ocean. We denude it at our peril.

Biodiversity may prove to be the defining issue of our age, and for that reason our cover story today is the first in a series of in-depth reports on the state of life on Earth, the causes of its decline and the many, often uplifting, stories of it being brought back.

You may think you already know everything there is to know, and that the situation is too depressing to think about. But be prepared to be surprised, and don’t turn away. The biggest cause of biodiversity loss is inaction through despair. Declines can be reversed. Endangered species can be rescued. Where there is life, there is always hope.

This article appeared in print under the headline “The state of life on Earth”