The Great Wave of Apathy – Why we need get serious about biodiversity loss


On 6 May 2019, the UN IPBES released a summary of its landmark global assessment report on biodiversity[1]. The warnings were stark – as a result of human activities, nature is declining at a rate unprecedented in human history, placing a million species at risk of extinction. Put simply, nature is in trouble, therefore we’re in trouble.

Such a grave conclusion from the most comprehensive assessment of biodiversity to date should have been a wake-up call. Instead, it barely got a mention on news programmes, at least in the UK. Granted, the release coincided with the birth of Prince Harry and Meghan Markle’s son – and who doesn’t love a royal baby – but still, some perspective please BBC.

Biodiversity loss is arguably just as great a threat to humanity as climate change. While climate change will almost certainly exacerbate biodiversity loss, if we solve one without the other, we’ll still be in trouble.

For example, say we somehow managed to sort climate change by building lots of fans that suck carbon dioxide from the air[2], hurrah. If we then proceeded to carry on as normal, before long we would be facing the threat of the collapse of nature, which could have similar consequences to climate change: food and freshwater shortages; mass displacement; crippling adaptation costs; and increased vulnerability to extreme weather.

Despite the significance of the threat posed by biodiversity loss, the issue hasn’t managed to capture the public’s attention in the same way as climate change. People have embraced specific aspects, such as plastic pollution and palm oil, but the wider issue is yet to have its own ‘Blue Planet II moment’. Perhaps this has to do with to our inherent sense of detachment from nature.

Modern life is convenient, far more convenient than at any other time in human history, but such convenience leads to detachment. In a single tap of a contactless card, we can exchange a fraction of our earnings for food wrapped in nice little packages, practically indistinguishable from other consumer goods. The transaction is so easy, we rarely stop to think about the associated impact on nature; even if we wanted to find out, it would take a lot of work to unravel.

Every second, tens of thousands of taps and clicks purchase goods across the globe; they patter like raindrops, accumulating to a tempest that can wipe out swathes of rainforest, deplete fish stocks, and plunder natural resources, whilst people carry on, mostly oblivious.

Some scientists now believe that we are at the start of the sixth mass extinction event, the first driven by human activities[3]. It might as well be called the “Great Wave of Apathy” – the extinction we sort of knew was happening but couldn’t summon the collective motivation to stop. It would make for a pretty lousy film compared to the fifth, nowhere near as dramatic as a giant asteroid slamming into Earth.

But there is still hope – if we collectively jolt awake from this slumber, there is still time to change course. To do so, we need to start treating biodiversity loss as seriously as climate change.

Happily, the solutions to biodiversity loss, such as stopping further deforestation and restoring degraded natural landscapes, have a mutually beneficial impact on mitigating climate change. So, it is not necessarily a case of prioritising one over the other.

Discussions about climate change should go hand in hand with biodiversity loss. In particular, we must be careful to avoid climate change solutions that exacerbate biodiversity loss. For example, policies that set binding targets on biofuels are thought to have inadvertently caused significant deforestation, which has adversely affected biodiversity[4].

This article discusses the drivers of biodiversity loss and the potential solutions. It covers:

  1. Why does biodiversity loss matter?
  2. The current state of nature
  3. What is causing biodiversity loss?
  4. Potential solutions
  5. What you can do to help

1. Why does biodiversity loss matter?

Humans are a product of the natural world – we evolved from nature and have been shaped by our surroundings. We have come a long way, but we are still highly reliant on nature; we are so specialised and well-adapted to our environment that we would be helpless if put in a different one. For example, plonk us on the surface of Mars without support and we would soon perish.

Technology can help us to survive in situations that our bodies couldn’t ordinarily handle. For example, astronauts can survive orbiting our planet for months at a time in the International Space Station (ISS). However, the ISS simply replicates Earth’s natural systems – such as regulating oxygen and carbon dioxide levels, water supply, waste management[5] – and is still heavily dependent on supplies from Earth. Further, the estimated cost of the ISS spread over its lifetime is US$7.5m per crew member per day[6].

So, whilst it is technically feasible to live without nature using artificial life support, the cost would be prohibitive. Even assuming we could reduce the cost of artificial life support massively, there is no way we could sustain our 7.7 billion (and growing) population.

Nature provides the basic conditions we need to survive for free – it regulates the air we breathe, pollinates our crops, recycles nutrients in the soil to maintain fertility, mitigates the impact of extreme weather and is a source of food, medicine and materials.

Biodiversity is also important to our quality of life and mental wellbeing. Several studies have found that spending time immersed in nature has measurable physiological and psychological benefits[7] – the Japanese created the concept of “Shinrin-Yoku” or forest bathing in the 1980s[8].

Biodiversity could even unlock future advances in technology and is an important insurance policy, for example through:

  • Engineering solutions – Engineers have long looked to nature for solutions. Brunel drew inspiration from a shipworm to design a tunnelling shield in the 1800s[9]; his creation was used to excavate the Thames Tunnel and the underlying concept is still used in tunnel boring machines today.  More recently, chief engineer Eiji Nakatsu refashioned the nose of the Shinkansen (a.k.a. bullet train) in the shape of a Kingfisher’s beak to overcome the problem of fast trains generating a loud boom when exiting a tunnel[10]. He also mimicked the design of owl feathers to redesign the train’s pantograph – he was a bit of a bird lover.
  • Medicines – Undiscovered species and natural compounds may hold the key to new medicines. Whilst most modern western medicines are produced synthetically, biomedical researchers still investigate natural compounds to create new medicines[11]. Biodiversity could, for example, hold the key to developing drugs to overcome antimicrobial resistance.
  • Food security – Domestic food crops were developed over time by crossbreeding wild varieties to select desirable traits. Due to intensive monoculture farming practices, we are now heavily reliant on a small number of domesticated varieties and so are exposed to large portions of our food supply being wiped out by disease (as has happened in the past). Biodiversity provides an insurance policy for developing new disease-resistant domestic varieties.

A seminal paper in 1997 attempted to put a value on benefits provided by the world’s ecosystems and natural capital. It estimated the value of tangible benefits provided by just 17 ecological systems to be US$33 trillion per year (on average)[12]. The study was updated for data up to 2011 and the estimate was revised upwards to US$125 trillion value per annum[13] – that’s more than the entire GDP of the world of c. US$85trillion in 2018[14].

We are pretty proud of our infrastructure, buildings and gadgets and we tend to dissociate ourselves with the natural world, but in reality, nature is still giving us a huge helping hand. It is a bit like a mother pushing her daughter on a swing – although the daughter feels like she’s flying all by herself, her mother is doing most of the work and gravity is doing the rest.

It is easy to take something for granted though when it has been there your whole life, not to mention that of your parents, grandparents and ancestors. The Holocene era spanning the last 10,000 years has been a period of remarkable stability in the history of the Earth. This has allowed life on Earth, including humans, to flourish – all of our recorded history is within this era.

It would be imprudent, however, to assume that it will stay like this forever. Humans are now so numerous and pervasive, that we are driving climate change at the same time as rapid biodiversity loss. Nature is resilient, but it is a complex web of linkages and relies on balance, which we have disrupted. When certain species fail, more pressure is placed on remaining life, leaving the entire ecosystem weaker – under sustained pressure, entire ecosystems can collapse.

For example, imagine a bed of sharp nails (pointy side up) – provided there are enough nails, you can lie down easily enough without injury, as your weight is distributed such that the pressure on any single nail is not enough to puncture your skin; but if you start taking out nails one by one and try again, well that’s going to end in tears.

The loss of the Golden Skiffia (a small fish) may sound mildly sad, but remote, like seeing on the global weather forecast that it is going to be stormy in Djibouti next week. However, if you look at the trend of the declining wild populations and read research that suggests that the sixth mass extinction is already underway, then the situation suddenly becomes more serious.

A mass extinction event could have similar consequences to some of the worst effects of climate change: food and freshwater shortages; displacement of millions of people; crippling adaptation costs; and reduced protection from natural disasters. It is unclear whether the human race could survive such an event over a sustained period. Even if we did, the world would be a pretty bleak place – it could take several million years until biodiversity is restored to its previous level[15].

2. The current state of nature

Nature is in a bad way, whichever way you look at it.

The population of wild vertebrate species has declined by 60% since 1970[16] and the rate of extinction in recent decades is as high as 1,000 times the natural background rate[17]. Scientists believe that these observations indicate that we are at the start of the Earth’s sixth mass extinction event[18].

The International Union for Conservation of Nature (IUCN) maintains a “Red List”, which assesses the extinction threat level of different species ranging from ‘least concerned’ to ‘critically endangered’.    In its latest update, the IUCN expanded its assessment to more than 100,000 species, almost 30% of which are threatened with extinction, 6% critically so[19]. Tellingly, not a single species was recorded as having an improved status. The extinction risk for different groups of species is summarised in the chart below.

Figure 1 – IUCN Red List – extinction risk by group of species

Source: “Summary for policymakers of the global assessment report on biodiversity and ecosystem services” (2019) UN IPBES. Based on data from the IUCN Red List.

Extrapolating the results of the Red List to the much larger ‘not evaluated’ pool suggests that up to a million species are threatened with extinction. Half of these extinctions could occur within decades, unless action is taken to reduce pressure on the natural world and restore habitats[20].

Iconic animals such as lions, elephants, tigers, rhinos and orangutans are all considered to be threatened species. Even the beloved koala is threatened as a result of extensive deforestation on Australia’s East Coast, mainly for livestock and timber.

If the current trend continues, it is likely that by the time today’s children have children, many of the popular animals in their storybooks will be as common in the wild as unicorns and mermaids.

Another recent study found that the insect population has declined rapidly in recent decades, with total biomass reducing at a rate of 2.5% per annum, mainly as result of intensive agriculture and widespread usage of chemical pesticides[21]. It is estimated that 40% of insect species are threatened with extinction over the next few decades. That’s concerning news for humanity, as over 75% of global crop types require pollinators to yield.

Tropical rainforests are also being lost at an alarming rate, with 2016-18 being the three worst years for deforestation since records began[22]. Rainforests are vital for biodiversity and are also a key ally in the fight against climate change, locking up vast amounts of carbon. The losses have mainly been driven by clearing for cattle, palm oil and cocoa plantations.

Deforestation of the Amazon – the world’s largest rainforest and home to more species than any other terrestrial ecosystem – has accelerated since Bolsonaro was inaugurated as the president of Brazil. The rate of deforestation increased by 88% in June 2019 compared to the same month last year[23]. This trend is expected to continue, as Bolsonaro has already loosened a number of environmental protections.

3. What is causing biodiversity loss?

In one word: humans. The rapid growth in the human population and our ever-increasing rate of consumption has had a detrimental impact on biodiversity.

The IPBES identified five key human-related drivers of the observed decline in nature. In order, they are:

  • Changes in land and sea use;
  • Direct exploitation (e.g. logging and fishing);
  • Climate change;
  • Pollution; and
  • Invasive species.

Each of these drivers are discussed in turn below.

i) Changes in land and sea use

The single largest driver of biodiversity loss for terrestrial and freshwater ecosystems is habitat destruction through changes in land use, predominately for the expansion of agriculture. Clearing of biodiverse rich rainforests in Brazil and South-East Asia for cattle and palm oil plantations respectively, has been particularly problematic.

Half of the world’s habitable land and almost three-quarters of available freshwater resources is dedicated to agriculture. Livestock takes up the lion’s share of that allocation – it uses almost 80% of all agricultural land, yet only provides 20% of the global calorie intake[24].

Some animals are more equal than others – the chart below shows the amount of land required to produce one gram of protein. Beef is the real standout, requiring almost 8 times more land than pork[25], which is why it has been such a prominent driver of deforestation. Beef also emits far more greenhouse gas emissions than any other source of protein (e.g. it is 6 times higher than pork). Beef should be thought of the coal of livestock.

Figure 2 – Land required to produce one gram of protein, by source

Source: Clark & Tilman (2017) “Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice”. Environmental Research Letters, Volume 12, Number 6. Sourced via Our World in Data

Aside from agriculture, the following changes in land use have also had a negative impact on nature:

  • Expansion of housing – urban areas have doubled since 1992, with low density sprawling cities being particularly problematic.
  • Infrastructure – global expansion of road and rail networks have fragmented habitats, for example, Britain’s planned HS2 railway threatens over 100 irreplaceable ancient woods[26]. The proliferation of dams and irrigation has affected rivers, with two-thirds of the world’s longest rivers no longer flowing freely[27].
  • Mining – increasing demand for resources has led to continued growth of mining, which has destroyed key habitats.

ii) Direct exploitation

When it comes to marine ecosystems, you may be surprised to read that plastic pollution – which has recently captured the attention of the world – is not the biggest problem. Even when combined with other types of pollution, plastic waste doesn’t even make the top three.

The single largest threat to marine life is overfishing. David Attenborough – who was instrumental raising the profile of plastic pollution – emphasised this point during a speech at the World Economic Forum in January 2019. Over 30% of fish stocks are overfished, while a further 60% are being harvested to the maximum sustainable limit[28].

Exploitation of resources on land, such as logging, is the second largest driver of the decline in terrestrial ecosystems.

iii) Climate change

Climate change is the third largest driver of the decline of all types of ecosystems. You may be surprised it is not higher. However, this finding is based on the level of warming experienced to date; it is a not forward-looking measure. If climate change continues unabated, it will have a growing impact on biodiversity. I discussed the threat of climate change in detail in a previous article.

iv) Pollution

Pollution is the fourth largest contributor to the decline in nature for all ecosystems. Widespread dumping of toxic chemicals, heavy metals and other industrial waste is having a significant adverse effect on both marine and terrestrial life.

For example, run-off from chemical fertilisers used in the agricultural production has led to algal blooms, which suffocate other marine life and cause ocean ‘dead-zones’. One of the largest dead-zones is an area of more than 20,000 square kilometres in the Gulf of Mexico[29].

Plastic pollution is a growing problem, particularly for marine life – the amount of plastic pollution in the oceans has increased tenfold since 1980[30]. The impact of microplastics, which have already entered food chains, is not well understood at this stage.

v) Invasive species

The fifth largest driver of biodiversity loss is invasive species, which can have a detrimental impact on local ecosystems, particularly on islands and other remote and isolated areas.

One well-known (and self-inflicted) example of an invasive species is the cane toad in Australia, which even featured on an episode of The Simpsons[31].

In 1935, cane toads were deliberately introduced in an attempt to control the native cane beetle, which was attacking sugar cane crops. As it turned out, cane toads were pretty hopeless at controlling cane beetles (they couldn’t jump high enough reach them), but they were exceptionally good at proliferating. Cane toads multiplied and spread and can now be found in 4 states with a population of more than 200 million[32].

Cane toads are poisonous and are particularly problematic for native wildlife, who haven’t yet developed the instinctive knowledge to avoid eating them. Various methods have been trialled to control cane toads, including cane toad golf, with little success.

4. Potential solutions

Mitigating biodiversity loss needn’t be a choice between humans and wildlife – that is not the right way to look at the problem. If we took steps to change our consumption patterns and to limit future population growth, for example through improving global education rates, then there would be plenty of room for both humans and nature to thrive.

Rising to this challenge will not be easy, but for the sake of both nature and humanity, we simply must do it.  The human population has doubled since 1970 and so we have to adjust our way of life accordingly – like a lot of things people did in the ‘70s, actions that have a disproportionate impact on the environment are no longer acceptable.

Changing our diets

The single largest action that we could take to restore biodiversity is to eat less meat. As discussed previously, livestock uses almost 80% of all agricultural land yet produces only 20% of the global calorie intake. In addition, livestock produces almost a fifth of global greenhouse emissions[33]. Cutting our meat intake would have substantial benefits for both biodiversity and climate change.

A study commissioned by medical journal The Lancet recently led to the development of a science-based diet that focuses on both health and sustainability[34] – it is the first of its kind and has since been dubbed the ‘planetary diet’. The planetary diet calls for a significant reduction in red meat (a 77% reduction for Europeans) and sugar, replaced by higher consumption of vegetables, fruit, pulses and nuts.

Although the planetary diet (or similar) would go a long way to addressing biodiversity loss and would also help mitigate client change, it would be virtually impossible for democratic governments to encourage widespread adoption of a (mostly) plant-based diet. I can just see the protests “they may take our lives, but they’ll never take our… cheeseburgers”.

Perhaps a simpler and more effective measure would be to phase-out subsidies for livestock and fishing. The EU alone spends a fifth of its budget, or c£24bn of taxpayers’ money, to support livestock[35], while global subsidies for fisheries total US$35 bn (in 2009 dollars)[36]. As a result, meat and seafood are far cheaper than they should be.

Without subsidies, the price of meat and seafood would increase to a level that better reflects the cost of production[37]. Consumers would then naturally substitute meat for plant-based alternatives, thus achieving the net effect of adopting a healthier and more planet-friendly diet.

Further, the money saved from removing subsidies could be redirected to providing additional services, tax-cuts or even climate change and biodiversity mitigation programmes.

Cut food waste

Almost one-third of the food produced for human consumption is wasted[38]. In other words, a third of agricultural land is dedicated to producing food that is thrown out. Against a backdrop of declining biodiversity, runaway greenhouse gas emissions and a world where millions are starving, such wastage is egregious.

Globally, the majority of food waste occurs prior to reaching consumers, for example due to unrealistic aesthetic standards and uneconomic prices during supply gluts. However, consumers in developed countries also waste 40% of the food they purchase; the amount thrown away is equivalent to the total net food production of sub-Saharan Africa.

The seemingly obvious act of not wasting food would have a positive impact on both biodiversity and climate change. Think of all of the redundant farmland that could be used to plant trees and restore natural habitats.

Governments, producers and consumers all need to do their part to address food wastage and find more sustainable solutions – such excessive wastage cannot continue.

Creating protected zones for wildlife

Nature has shown it has the ability to recover if left alone. For example, while the 4km wide demilitarised zone (DMZ) dividing the two Koreas is a no-go for humans, it has become a haven for wildlife. A rare Asiatic black bear was recently photographed in the DMZ by an unmanned camera, indicating a healthy ecosystem. The DMZ is thought to be home to more than 5,000 different plant and animal species[39].

Now, that’s not to say the world needs more DMZs or disaster areas – creating national parks and marine sanctuaries would have the same effect. Dedicated conservation areas protect wildlife from destructive human activities, such as logging and fishing, and give nature the chance to recover.

One particular proposal that is close to my heart is the Great Forest National Park in my home state, Victoria, Australia. This park would protect a large section of Victoria’s native forests from a rampant and loss-making logging industry and would secure the habitat of the critically endangered Leadbeater’s Possum. The park is supported by Sir David Attenborough, Dr Jane Goodall and 70% of Victorian voters, yet the government still cannot seem find the courage to implement the proposal. 

Rewilding as a solution to biodiversity and climate change

Restoring natural habitats, or rewilding, would help slow biodiversity loss and capture carbon dioxide at the same time. Natural landscapes, such as forests, mangroves, peatlands and meadows have enormous potential to support biodiversity and store carbon.

A group called Rewilding Britain calls for farming subsidies to be redirected towards creating native woodlands and meadows[40]. It believes that up to a quarter of UK’s land could be restored to nature, making a significant contribution to cutting the nation’s greenhouse gas emissions to zero.

Following a similar theme, a group of scientists, artists and activists (including Greta Thunberg) wrote an open letter calling for rewilding as a solution to the climate change and biodiversity crises[41]. There is even an open UK parliament petition calling for rewilding as a solution – at the time of writing it has over 100,000 signatures, which means it will be debated in parliament.

A recent study found that restoring forests through planting billions of trees would be by far the cheapest way to tackle climate change and it could be done without encroaching on farmland or urban areas[42].  Such a solution would also have a positive effect on biodiversity, provided the restoration was carefully managed – planting monoculture forests on already biodiverse-rich areas (such as native meadows and grasslands) could inadvertently have an adverse impact on biodiversity.

Not all solutions need to be on such a grand scale; sometimes the little things are just as important. For example, I’ve noticed in my local park this year, the council has planted large areas with wildflower seeds and have let them grow freely over the summer. They’re a joy to look at and they support a wealth of life – each time I walk past I see bumblebees and butterflies and hear the buzz of thousands of insects. The banks require far less maintenance, as there is no need to mow or use herbicides, so it is a win-win.

 A ‘Paris Agreement’ for biodiversity

The closest thing we have to a global agreement on biodiversity is the Convention on Biological Diversity (CBD), which started in 1993. At the tenth Conference of Parties (COP), a revised plan for biodiversity was adopted, which included 20 targets for the period 2011-20, called the ‘Aichi Targets’. The targets are grouped into five themes, all designed to address biodiversity loss.

Performance against the targets has been dismal. Only four of over 50 subgoals have been rated as ‘good progress’ or green and not a single target has been rated as green overall[43]. I’ve read my fair share of RAG (Red-Amber-Green status) reports over the years, but I can’t recall seeing one quite as bad as this one.

It is clear that far stronger global action is needed to address the challenge of biodiversity loss. The world needs the equivalent of a Paris Agreement for Biodiversity.

5. What you can do to help

There are a number of steps that you can take to reduce your impact on nature and mitigate biodiversity loss:

  • Change your diet – Eating less meat is probably the single largest thing you can do to help nature. If you can’t contemplate going vegan or vegetarian, consider one or more meat-free days a week and switching to meats with a lower impact – chicken is far better than beef for example. In addition, try to buy organic produce if you have the means to – organic food is produced without chemical pesticides and so it is far better for insects and soil fertility.
  • Have a conversation about biodiversity – it is important that we escalate the issue of biodiversity loss. Biodiversity loss and climate change should be discussed in unison and join solutions developed.
  • Consider supporting a charity – there are lots of good environmental charities out there. They broadly fall into the categories of direct habitat maintenance and restoration (e.g. Woodland Trust and RSBP), lobbying (e.g. Wilderness Society) and conservation (e.g. WWF).
  • Go wild – If you’re lucky enough to have a garden, consider planting flowers, shrubs and trees that are native to your area. This will act like an island haven for wildlife enabling safe passage through the urban area safely. I’ve lived in apartments ever since moving out of home many years ago, but I still grow flowers and plants on my balcony, which are visited by birds and bees.
  • Read – there are lots of good books on biodiversity. If I had to recommend one, it would actually be a fiction book called “The Overstory” by Richard Powers. It is beautifully written and will almost certainly make you think about trees differently. It won the 2019 Pulitzer Prize for fiction and came close to winning the Man Booker Prize in 2018.
  • Look for sustainable labels – certification schemes are far from perfect, but at the very least, they ensure that certain minimum criteria are met. For paper and wood, FSC certification is the definitive scheme (FSC 100% and FSC recycled are best, while FSC mix is weakest). Rainforest Alliance and UTZ are good for food, coffee and cocoa, while Marine Stewardship Council is the main scheme for sustainable fishing. RSPO promotes sustainable palm oil.


[1] “Summary for policymakers of the global assessment report on biodiversity and ecosystem services” (2019) UN Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.

[2] A company called Carbon Engineering has developed a method to extract CO2 from the air using a series of large fans. However, somewhat perversely, the CO2 captured by the pilot plant is being used to help extract more oil from the ground. In order to have a material impact on climate change, the cost per tonne of CO2 captured will need to reduce significantly, and of the extracted CO2 will need to put to better use.

[3] Ceballos et al. (2017) “Population losses and the sixth mass extinction” Proceedings of the National Academy of Sciences, Jul 2017, 114 (30)

[4] Gerasimchuck and Koh (2013) “The EU Biofuel Policy and Palm Oil:Cutting subsidies or cutting rainforest?” International Institute for Sustainable Development

[5] “Life Support Systems” NASA,

[6] Lafleur, Claude (2010) “Costs of US piloted programs”. The Space Review. Based on $150bn spread over an assumed 20,000 crew days.

[7] Bratman, et al. (2015) “Nature experience reduces rumination and subgenual prefrontal cortex activation” Proceedings of the National Academy of Science.

[8] Hansen, et al. (2017) “Shinrin-Yoku (Forest Bathing) and Nature Therapy: A State-of-the-Art Review”, International Journal of Environmental Research and Public Health

[9] Becket, Derrick (1980) “Brunel’s Britain.” David & Charles.

[10] “The story of Eiji Nakatsu” Japan For Sustainability, JFS Biomimicry Interview Series, Newsletter No.31 (March 2005)

[11] Neergheen-Bhujun, et al. (2017) “Biodiversity, drug discovery, and the future of global health: Introducing the biodiversity to biomedicine consortium, a call to action” Journal of Global Health

[12] Costanza, et al. (1997) “The value of the world’s ecosystem services and natural capital” Nature, 387

[13] Costanza, et al. (2014) “Changes in the global value of ecosystem services” Global Environmental Change, Volume 26, May 2014, Pages 152-158

[14] “Gross domestic product 2018”, World Development Indicators database, World Bank, 1 July 2019

[15] “Will Humans Survive the Sixth Great Extinction?” National Geographic, June 23, 2015.

[16] Grooten, M., et al. (2018) “Living Planet Report – 2018: Aiming Higher.” WWF.

[17] De Vos, et al. (2014) “Estimating the normal background rate of species extinction”, Conservation Biology

[18] Ceballos et al. (2017) “Population losses and the sixth mass extinction” Proceedings of the National Academy of Sciences, Jul 2017, 114 (30)

[19] The IUCN Red List of Threatened Species. Version 2019-2.

[20] “Summary for policymakers of the global assessment report on biodiversity and ecosystem services” (2019) UN Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.

[21] Sanchez-Bayo, F. and Wyckhuys, K. (2019) “Worldwide decline of the entomofauna: A review of its drivers.” Biological Conservation, 232 8-27.

[22] “‘Death by a thousand cuts’: vast expanse of rainforest lost in 2018” The Guardian, 25 April 2019

[23] “Brazil: huge rise in Amazon destruction under Bolsonaro, figures show” The Guardian, 3 July 2019.

[24] Max Roser and Hannah Ritchie (2019) – “Yields and Land Use in Agriculture”. Published online at Retrieved from: ‘’

[25] Clark & Tilman (2017) “Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice”. Environmental Research Letters, Volume 12, Number 6.

[26] “HS2 rail link”, Woodland Trust

[27] “Two-thirds of the longest rivers no longer flow freely—and it’s harming us”, National Geographic, 8 May 2019

[28] “The state of the world fisheries and aquaculture” (2018) Food and Agriculture Organization of the United Nations

[29] “Gulf of Mexico ‘dead zone’ is the largest ever measured”, National Oceanic and Atmospheric Administration, August 2, 2017.

[30] “Summary for policymakers of the global assessment report on biodiversity and ecosystem services” (2019) UN Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.

[31] Cane toads were referenced in The Simpsons episode “Bart vs. Australia”.

[32] “Killing off the cane toad” (2006), Institute of Molecular Bioscience, University of Queensland.

[33] Sejian V. et al. (2015) “Global Warming: Role of Livestock”. Chapter in: Sejian V., et al. “Climate Change Impact on Livestock: Adaptation and Mitigation”. Springer, New Delhi (2015)”

[34] Willet, et al. (2019) “Food in the Anthropocene: the EAT–Lancet Commission on healthy diets from sustainable food systems”, The Lancet, 393: 447-92.

[35] “Feeding the Problem: the dangerous intensification of animal farming in Europe” (2019) Greenpeace European Unit.

[36] Sumaila, et al. (2016) “Global fisheries subsidies: An updated estimate” Marine Policy, Volume 69

[37] In practice, as not all global subsides are equal, so it is possible that import tariffs or quotas would be required to avoid foreign producers flooding the market and pushing prices back down.

[38] “Global food losses and food waste – Extent, causes and prevention”(2011) Food and Agricultural Organisation of United Nations.

[39] “Rare Asian black bear spotted in Korean DMZ” The Japan Times, 11 May 2019.

[40] “Rewild a quarter of UK to fight climate crisis, campaigners urge”, The Guardian, 21 May 2019.

[41] “A natural solution to the climate disaster” The Guardian, 3 April 2019

[42] Bastin, J., et al. “The global tree restoration potential”, Science, 5 July 2019, Vol. 365, Issue 6448

[43] “Summary for policymakers of the global assessment report on biodiversity and ecosystem services” (2019) UN Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.


Approaching 10 billion – Can our planet cope with population growth?

The physical capabilities of humans are lacklustre compared to most animals – we are not the strongest, nor the fastest and our senses are not the sharpest. In a bare-handed confrontation with a lion, for instance, a human would not fare well. Yet through our cunning, cooperation and resourcefulness, we have become unrivalled.

In the early stages of human history, our ability to create stone tools and control fire gave us a significant survival advantage. These skills enabled us to become effective hunter-gatherers and to prosper.

Over time, our technology improved and our influence grew. The advent of farming around 10,000 BC enabled us to better control our food supply and to settle in communities, thereby increasing our population.

The Industrial Revolution, which started around the middle of the 18th century, was a watershed in human history.  By harnessing the power of machines and unleashing the condensed energy within fossil fuels, we supercharged our advancement and the population exploded, growing from 1 billion to 7 billion over a period of just 200 years.

The unprecedented growth in our population and consumption over the last two centuries has had a devastating impact on our planet. It has been a key driver of a number of environmental issues, including: climate change, deforestation, loss of biodiversity, depletion of fish stocks and widespread plastic pollution.

At the World Economic Forum in Davos in January, Sir David Attenborough remarked:

“We are now so numerous, so powerful, so all pervasive, the mechanisms we have for destruction are so wholesale and so frightening that we can exterminate whole ecosystems without even noticing it.”[1]

It seems obvious that our environmental problems will become more difficult to solve as the human population continues to grow to 10 billion by 2050[2], yet the link is rarely mentioned. Why?

For one thing, all human life is sacred; everyone deserves the chance to live a long and happy life, to love and to raise a family. The concept that the simple state of being has an adverse effect on the planet is difficult to come to terms with. It is comparatively easier to look at ways to reduce our impact or to focus on specific causes of environmental problems, such as burning fossil fuels.

If we are to have any hope of tackling environmental issues and feeding the world, however, we must at least consider whether there are any ethical and feasible solutions to curtail population growth – we must address the elephant in the room. There is no escaping the fact that our planet has finite resources and hence there is a natural limit to how many people it can sustain.

This article discusses:

  1. The link between the human population and the environment;
  2. Historical population growth;
  3. Projected future population growth; and
  4. Ethical options for curtailing population growth.

1. The link between the human population and the environment

Rapid growth in the human population has had a pernicious effect on the natural world. Since 1970, the human population has almost doubled, while over the same period, the population of the natural world has dropped by 60%[3]. The effect has been more pronounced in South and Central America, where wildlife has suffered an 89% decrease.

At this rate, humans are on track to cause the sixth mass-extinction event (or the Holocene extinction)[4]. It is difficult to see how the natural world will survive the triple threat of climate change, a further doubling of the human population and the snowball effect of collapsing ecosystems.

While humans are not physically large – standing shoulder to shoulder, the entire population could fit into an area the size of Los Angeles – we cast a long shadow. We need a lot of space and resources to sustain our lifestyles (e.g. for housing and land for agriculture to feed us), especially in the developed world. So, it unsurprising then that as the human population has grown, deforestation and habitat loss has increased, decimating the populations of other species in the process. We have effectively taken space and resources away from the natural world.

The charts below show how growth the human population and our consumption is linked to the deterioration of a number of key environmental indicators, including: degradation of ecosystems, increased loss of tropical forests and increased acidification of the ocean.

Source: WWF Living planet report 2018

One way to assess the sustainability of our combined impact is to compare the level at which we consume resources and generate waste with the natural capacity of our planet. This concept is referred to as our ‘ecological footprint’[5].

On this metric, we are running a large ecological budget deficit: we would need 1.7 earths to sustain our current consumption patterns.  In other words, we are living well beyond our means and are only supporting this by raiding the planetary savings account that has been built up over billions of years, which clearly is not sustainable – you cannot live off garage sales forever.

We have depleted fish stocks, cleared forests for pastures, drained inland lakes and acquirers, melted glaciers and have irrigated rivers until they run dry. Even if we get back into the black, it will take these reserves centuries, or even millennia, to recover.

The Global Footprint Network produces a metric called ‘earth overshoot day’, which measures the point in the year when we exceed our annual budget, i.e. when our consumption exceeds the natural capacity of the planet. In 1970, when the global population was around 3.7 bn, we were just about breaking even. Now, as our population draws closer to 7.7 bn, we are blowing our annual budget by the 1st of August. 

As the chart below shows, the day that we have exceeded our annual budget has moved ever forward as the population has increased.

The relationship between our ecological impact and our population is a simple one: our total ecological footprint is the product of the global population and the average footprint per capital. Despite this, we tend to avoid linking population growth with environmental issues; we typically focus on measures to change our consumption and reduce our impact.

While measures to reduce our individual impact are beneficial and absolutely necessary, it is also important to consider that if our population were to double again, we would need to halve our average individual impact just to tread water. We would then need to halve our impact again to balance the ecological books.

It is unclear exactly how long we can continue to live beyond the means of the planet. The longer we do so and as the gap widens, the more difficult it will be for all life on earth, including humans. And it is the poorest who will be disproportionally impacted.

As our population and ecological footprint increases, we are more likely to face critical shortages of fresh water, widespread famine, epidemics and more frequent wars and civil unrest over dwindling resources.

Further, the capacity of the earth to support life is likely to decrease over time with the effects of climate change, biodiversity loss and the depletion of natural resources – think of this as the effect of credit card debt catching up with us. The effect of climate change only increases the magnitude of the challenge of reaching a sustainable level of consumption.

In his book, ‘An Essay on the Principle of Population’, Thomas Malthus argued that humans have a tendency to utilise abundance of resources for population growth rather than maintain a higher standard of living. He wrote:

“That population does invariably increase where there are the means of subsistence, the history of every people that have ever existed will abundantly prove.

And that the superior power of population cannot be checked without producing misery or vice…”[6]

In other words, Malthus was not optimistic that humankind could prevent itself from reaching its natural limit, which he believed would inevitably result in misery (e.g. famine, disease and war).

Malthus’ theory reminds us that we cannot ignore the impact of population growth if we are to avoid a scenario where ‘misery’ limits our population for us. Such a scenario would be devasting for both humans and the natural world.

2. Historical population growth

It took 200,000 years for the human population to reach 1 billion and only 200 more years for it to increase to 7 billion.

Modern humans evolved in Africa around 200,000 years ago and began migrating across the earth. To start with, we were hunter-gatherers and our population was low: less than 1 million.

There were two significant events in human history that led to rapid population growth:

a) The agricultural revolution – the advent of farming around 10,000 BC provided a more stable and controllable source of food. It allowed humans to settle in communities increasing the supportable density of populations.

Over several thousand years, agricultural practices improved and spread from the Middle East across the globe and the population increased to around 700m by the mid-1700s

b) The industrial revolution – the industrial revolution, which started around 1760 led to exponential growth in the human population, through improvements in medicine and food production, transportation and storage, which reduced mortality rates, particularly for infants.

Fast forward to 2019 and there are now 7.7 billion people on this planet[7].

The video below from the American Museum of Natural History gives a visual overview of historical population growth.

3. Projected future population growth

Future population growth is inherently uncertain and so all projections must make assumptions regarding changes in the key drivers of the population. The three main drivers are:

i) Mortality rates (i.e. percentage of deaths in the population per annum)

Improvements in mortality rates increase the average length of time that a person is expected to live (“life expectancy”) and therefore cause the population to grow.

Life expectancies have improved dramatically over the last few centuries[8], mostly driven by advances in medicine and technology. This has been a significant contributor to the increase in the steady-state population. For example, 200 years ago, it would be common for a child and their parents to walk the earth together. Now, a child is likely to be able to share a meal with their parents, their grandparents and even their great grandparents.

Mortality rates are expected to continue to improve, albeit at a slower rate. Hence, mortality improvements are likely to have relatively smaller impact on future population growth.

ii) Fertility rates

If the number of live births per woman (Total Fertility Rate, or “TFR”) is greater than the rate needed to sustain the population (the “Replacement Rate”), the population will grow. The Replacement Rate is linked to mortality rates – if there was no female mortality between birth and childbearing age, the rate would be 2.0. In developed nations, the replacement rate is close to 2.1, while the global average replacement rate is 2.3[9].

The global average total fertility rate is currently 2.5 and hence the steady-state population is increasing. However, the TFR varies significantly by country and region, leading to vast differences in population growth across the planet.

In the developed world, the TFR is less than 2, but in the least developed nations it is closer to 4. In Niger, the TFR is over 7 live births per woman[10]. The chart below shows the extent of the variation in the TFR by country.

Total fertility rate by country

Source: CIA World Factbook

iii) Population momentum – The population changes as it moves from the current level to the steady-state (or equilibrium). This effect is referred to as population momentum and explains why the population can continue to grow even if mortality rates have stabilised and the total fertility rate has settled at the replacement rate.  Momentum effects can continue for decades where there is a significant demographic transition and where the difference between the current and steady-state is large.

The UN performs biennial projections of the world population, which take into account estimated changes in all three key drivers of growth (i.e. mortality rates, total fertility rates and population momentum). The chart below shows the projections from the latest revision in 2017.

Source: “World Population Prospects: The 2017 Revision” (2017) UN Population Division

In the best estimate scenario (i.e. 50/50 chance of being too high or low), the population is projected to reach around 10 billion people by 2050 and peak at just over 11 billion people in 2100. This scenario assumes that the TFR drops from 2.5 live births per woman to 2.2 in 2050 and then to 2.0 by 2100.

If the estimated TFR is underestimated by just 0.5 live births per woman, then the population will reach 16.5 billion by 2100. And if the total fertility rate remains at the current level, the population will continue to increase and will reach 26 billion by 2100.

All of the UN scenarios assume the population continues to grow unencumbered, i.e. that the growth can be supported by the planet’s existing limited resources. However, as discussed previously, this seems unlikely, particularly in the constant fertility scenario (with 26 billion people by 2100) – if growth continues at this rate, then ‘misery’ is likely to impose a natural limit on the population.

4. Ethical options for curtailing population growth

There are no easy options for limiting our population to a sustainable level. Immediately ruling out a Soylent Green type scenario[11] of state ‘encouraged’ euthanasia, the only ethical way to arrest population growth is to transition to a global average total fertility rate of fewer than 2 live births per woman.

Some countries have implemented policies to restrict fertility rates, most notably China with its one-child policy (1978-2014), which was subsequently increased to a two-child policy. The one-child policy has been successful in curbing China’s population growth – government officials estimate that China’s population would be 400 million higher today without the policy. However, the policy has been contentious and is not without critics.

It is doubtful whether strict population controls could be applied in democratic countries. These policies ultimately take away a woman’s right to choose, are questionable from an ethical standpoint and are unpopular – people would rather the government stays out of our bedrooms.

A potential method to influence the total fertility rate in a more positive and ethical way is through investing in education and the empowerment of women. Historical data across regions clearly shows a strong negative correlation between years of education and total fertility rate, as seen in the chart below. That is, women who attain a higher level of education are more likely to have smaller families.  For example, in Ghana, the total fertility rate of women with a high school education is 2-3 compared to 6 for women with no education[12].

While there is some debate as to whether the relationship between education and fertility rates is a causal one[13] (i.e. whether higher education drives lower fertility rates), there are a number of qualitative reasons as to why this is likely to be the case. Women who attain a higher level of education:

  • Are better able to support themselves and are more likely to feel empowered to assert their views on important topics such as their preferred family size;
  • Have greater knowledge of modern birth control methods and are more likely to utilise, these;
  • Have better employment prospects and hence a higher opportunity cost of bearing children (e.g. educated women are more likely to delay having children until they establish their careers);
  • Are better able to support their children (through higher incomes and better knowledge of prenatal and child care) and are therefore more confident that their children will survive; and
  • Have a wider and more informed view of their ideal family size, through greater exposure to their community and global social networks.

Austrian based research centres, the International Institute for Applied Systems (IIASA) and the Wittgenstein Centre (WC), include the link between education level and fertility rates in their highly-regarded population projections. Their projections consider global trends in education and how these are likely to affect total fertility rates. They define a number of scenarios around future education:

  1. SSP1 Accelerated educational development – An optimistic scenario where developing countries accelerate their investment in education and achieve a similar rate of improvement to that achieved by standout countries, such as South Korea, in recent decades.
  2. SSP2 Best estimate (or Global Education Trend) – Developing countries continue to improve education levels at the historical average rates observed for more advanced countries.
  3. SSP3 Stalled educational development – The improvement in education levels for developing countries is slower than the historical average and fertility rates remain high.

The chart below shows the population projections for the three different scenarios alongside the UN best estimate case, for reference.

Source: Wittgenstein Centre for Demography and Global Human Capital (2015). Wittgenstein Centre Data Explorer Version 1.2.     


The WC and IIASA best estimate projection indicates a slower population growth profile than the UN best estimate, with the global population peaking at 9.4 bn in 2070. Under a more optimistic scenario, where education levels improve at a higher rate, the population peaks at 8.5 bn in 2055 before falling below current levels by 2100. However, if improvements in education stagnate, then the fertility rate is estimated to remain above 2 and the population continues to grow beyond 12.8bn after 2100.

These projections and the historical correlation data demonstrate the crucial role that investing in education and empowering women could play in limiting the human population to a sustainable level. In the accelerated education scenario, the population peaks at 8.5bn, just 0.8bn higher than today and solving our environmental issues and eradicating poverty seem just that bit more achievable.

Even if this solution is less effective at reducing population growth than expected, it would lead to a better educated population and would improve gender equality – significant benefits in their own right.

5. What you can do

There are three easy and effective steps that everyone, regardless of age or gender, can take:

  • Reduce your impact on the environment – as our population continues to grow, it becomes increasingly important to take steps to reduce our average ecological footprint. Everyone can take steps to reduce their ecological footprint and this blog will discuss different ways to do so in future entries.
  • Have a conversation about population – it is important that we discuss the link between population growth and environmental issues, such as climate change. Admitting a problem is the first step to solving it. We should encourage governments to invest in education in developing nations and combat religious or societal practices that encourage procreation and/or create barriers to access contraception. For example, linking regular aid allocations to educational and social development goals could help foster a longer-term solution to alleviating poverty.
  • Support charities that focus on education as a long-term solution to sustainable growth – for example, Campaign For Female Education ( ) is dedicated to eradicating poverty in Africa through the education of females and the empowerment of young women. It has supported over 2.6 million students to attend primary and secondary school.

[1] Sir David Attenborough in an interview with Prince William at the World Economic Forum, Davos, 22 January 2019

[2] UN World Population Projections, 2017 revision

[3] “WWF Living Planet Report – 2018: Aiming Higher” (2018) Grooten, M. and Almond, R.E.A.(Eds).

[4] Kolbert, E. ‘The Sixth Extinction: An Unnatural History’ (2014), Henry Holt and Company

[5] Global footprint network,

[6] Malthus, T. “An Essay on the Principle of Population” (1798)

[7] World Population Clock, January 2019, (

[8] For example, male life expectancy at birth in England increased from around 40 years in 1850 to 79 years in 2017.

[9] Espenshade TJ, Guzman JC, Westoff CF “The surprising global variation in replacement fertility” (2003).  Population Research and Policy Review

[10] UN Population Division (2017 revision)

[11] Soylent Green is a 1973 dystopian film centred on overpopulation and a suffering planet. It includes the famous quote “Soylent Green is people!”.

[12] Pradhan, E. “Female Education and Childbearing: A Closer Look at the Data” (2015), The World Bank 

[13] Jungho Kim (2016) “Female education and its impact on fertility” IZA World of Labour