In the midst of mass extinction?

Photo by Oleksandr Filatov

Biodiversity is at risk. It’s a fact that we have lost a significant number of species over the last 300 years: mammals, birds, vertebrates. Species that we pay close attention to are typically ones that we are aware we’ve lost; but, of course, those species – animals with backbones, even vascular plants – are not most things. Most things are arthropods, insects of various kinds, fungi; things that we pay relatively little attention to but are just as important in terms of functioning of ecosystems and the processes that they are engaged in that help support human life on Earth.

People have said that we are in the midst of a mass extinction event. I would suggest, rather, that we are at the beginning of a mass extinction event. We’ve lost the first 1% or 2%. A mass extinction event means that you lose 10% to 90% of things. There have been six such mass extinctions in the past. The last one was about 65 million years ago, when we lost our dinosaurs, amongst others. We know what caused that. We also know what’s causing the current one. We have been losing species at an accelerating rate for the last few hundred years. That’s a very short time period in terms of evolution and the ecology of the Earth. It’s an eyeblink. Extinction events can take place over hundreds or thousands of years. If we continue to lose species at the rate at which we’re currently doing, then indeed we are in the midst of the leading edge of a mass extinction event. There’s no question that that’s the case.

Knowledge that we are lacking

Most people haven’t understood that we have no idea about the vast majority of things on Earth. We haven’t collected or identified them. We don’t know anything about their life histories, their ecology, where they live or what they do. We are still ignorant about the vast majority of the Earth’s biodiversity; so, in fact, we don’t know what it is that we’re losing. It’s also surprisingly difficult to tell when you’ve lost the last individual of a species. You’ve got to look very hard to know there’s no more of it left. Documenting extinctions, therefore, is quite difficult.

The best we can do is infer that something has become extinct statistically and make judgements about the overall rate. It is because it’s so complicated to observe directly that it’s very hard to motivate people to do anything about it. It’s also difficult for us to communicate the extent of these processes or the rapidity with which they are unfolding in geological time. We are relatively short-lived as individuals – 80, 100 years if we’re lucky – but ecological and evolutionary timescales are much longer than that. As a consequence, we tend to reset our thinking about what is natural and what is to be expected with each new generation of humans, and we lose sight of how quickly things are changing around us. These changes are coming like a locomotive. We’re not prepared, and we’re being very slow to adjust our thinking and our way of interacting with the environment to ensure that the place in which we live continues to be liveable.

The major drivers of biodiversity loss

Photo by SanderMeertinsPhotography

There are a lot of species that are either endangered or critically endangered, meaning that they face the risk of extinction within the next few decades. It’s very likely that we’ll lose at least some of those. We know which ones they are, to some extent, if they are amongst those things in which we are most interested – birds, mammals, reptiles, amphibians and vascular plants. The ICUN in Switzerland keeps detailed lists and documents the kinds of steps we could take to protect those species.

The broader drivers of loss of species are the size of the human population and per capita consumption of natural resources. The kinds of things we consume could be adjusted simply by altering our diet. Our expectations in terms of resource consumption are about what each generation expects in terms of having somewhere to live, the amount of space they have to live in and the standard of living that we anticipate having for ourselves and our children. Those are difficult things for people to adjust to, but they are the underlying drivers of things that cause, as a consequence, the global expansion of cities and agricultural areas, the loss of habitat, land clearing and forest clearance, globally. These things continue almost unabated.

An enforced transition

Society needs to change the way it considers personal aspirations and to have a better view of the collective impact of our activities on the environment. I don’t know that I can see another solution, because the idea that we can tell people things are bad and they’ll change their minds is not going to work. It may be an intractable problem. People talk about benign transitions being changes in societies – societies as a whole that move towards a more sustainable future – and transitions that are not benign, those which precipitate crises that lead to enforced changes in behaviour.

We may see things precipitated by climate change, for example, that transcend our expectations, that lead to more rapid changes than we are currently expecting. If those things happen, if the tail distributions of our expectations arise and sea levels and temperatures change more than we think, there could be wholesale changes to economic food systems that trigger changes in the way society behaves. My deep fear about those scenarios is that the people who are most likely to suffer the most serious consequences of those transitions are the people most vulnerable to them: people who are poorest, people in the least able circumstances, people who are in societies who are least able to respond will bear the consequences of the decisions that we, globally, are taking as we speak.

Conservation action

Designating protected areas, marine parks, national parks, terrestrial areas and freshwater zones is about creating legislation to protect endangered species so that when a species is threatened, we can impose particular restrictions on what people can do in its habitat. There’s expenditure on ecosystem services and on enhancing the interactions between people and their environments in various places around the world that will both conserve biodiversity and find better solutions for people’s livelihoods.

There are certainly success stories. There are species which, without human intervention, would have become extinct. There are species that will probably persist long-term because of the things that people have done. They give us some hope that our knowledge can be used to good effect to at least delay, if not stave off, the extinction of some of the species that we’re affecting. They’re all great actions, but there are simply not enough of them around the world to make a big enough difference.

The orange-bellied parrot

Photo by Agami Photo Agency

The orange-bellied parrot is one of the few migratory parrots in the world. There are roughly half a dozen species of parrots that migrate from one place to another. The orange-bellied parrot migrates from Tasmania in southern Australia to the mainland of Australia each year, in the wintertime. In the 1850s, there were tens of thousands of these birds; they’d spend summertime in Tasmania and breed their offspring. They fly over the Tasman Sea to the mainland and then spread out across southern Australia, going westward towards Adelaide and eastward and northward towards Sydney, inhabiting the salt marshes and wetlands in that part of the world. But the population has been slowly shrinking: there were about 1,500 of those birds left in 1980. When I last looked, there were about 150. Their population has slowly declined over a period of a hundred years to the point where there are virtually none left. However, they’re not extinct – though had not a group of very dedicated veterinary scientists and ecologists intervened, they certainly would be.

A delicate, endangered habitat

With regard to the fires and the Australian landscape, I think particularly of animals like the Leadbeater’s possum. The Leadbeater’s possum was thought to be extinct, and was rediscovered in the central highlands of Victoria a few decades back. It lives in cavities in ancient trees, in a landscape that is characterised by fire. In the places that are frequently burned, there are large, old eucalyptus trees. These trees can be up to 100 metres tall and with very large girths. It takes them a long time to grow. When these trees are about 100 or 125 years old, they start to develop cavities: branches start to fall, and the Leadbeater’s possum forms dens in their cavities. It takes a long time for the habitat that this species needs to emerge after a fire.

It needs places that burn, but only burn every 200 or 400 years. As a consequence, the habitat it requires is extensive and rather grand. It’s a spectacular-looking place. With the fires occurring as often as they currently are, the habitat for that species will be lost. Now, that’s a consequence of there being more people around – and people do tend to light fires – and it’s a consequence of lightning strikes. Fires are essentially a product of how hot it is, how much fuel there is and whether there’s a source of ignition. With climate change, increasing temperatures, increasing human population size, those things are just getting worse, and the habitat for this species is shrinking.

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Biodiversity at risk

Bolam, F. C., Mair, L., Angelico, M., et al. (2020). How many bird and mammal extinctions has recent conservation action prevented? Conservation Letters: A journal of the Society for Conservation Biology, e12762.

Ball, J. G. C., Burgman, M. A., Goldman, E. D., et al. (2020). Protecting biodiversity and economic returns in resource-rich tropical forests. Conservation Biology.

Rowland, J. A., Bland, L. M., Keith, D. A., et al. (2019). Ecosystem indices to support global biodiversity conservation. Conservation Letters: A Journal of the Society for Conservation Biology, 13(1).

Biodiversity and the danger of mass extinction