woman walking in the mountains

Key challenges for rewilding 30% of the planet

Rewilding is a proposal to avoid a dystopian future and 30% rewilding is needed to keep us within planetary limits.

Rewilding is a terrific concept. 

The idea is to return landscapes that were manipulated and managed by humans back to their natural state, ideally with some multiple use options, such as harvesting from forest trees or running wind farms in the middle of natural savannas. 

This alternative future described for everyone by Sir David Attenborough in A life on our planet is to return some balance to nature by rewilding 30% of the globe back to what it was prior to human intervention. Rewilding a third of the landscape is also the expected level of change needed to retain a reasonable amount of global biodiversity and the ecosystem services humanity needs to survive. 

At least 30% of the land and 30% of the ocean must be hands-off so that nature can recover, degradation can slow down, and the essential services that nature provides can persist. 

Nature is resilient and will recover quickly in degraded areas given a chance. Rewilding is readily achieved by natural regeneration plus an introduction or two. All that has to happen is that human impacts are removed or mitigated.

Whilst humans take their hands off a third of the landscape, the requirement remains to grow enough food to feed 7.8 billion people. The population is 6 billion more than in 1900 when humans began to use the internal combustion engine for automobiles and trucks. 

Whilst we currently grow enough food to feed everyone globally there are problems with food distribution, access to food, and waste. Some researchers estimate that the already staggering amount of food grown each year will need a net increase of 2% annually for the next 30 years to meet the demand for adequate nutrition. And beyond 2050 this level of production is expected to rise until a demographic transition is complete. 

At its crudest, the challenge is to rewild a third of the planet and still feed everyone well.

Sharing a third of the planet with nature is reasonable given two key assumptions:

  1.  that standards of living continue to grow, especially for those doing it tough, and everyone maintains their well-being with an equal opportunity for a slice of the pie. 
  1. rewilding will deliver the ecosystem services needed to meet the first assumption
semi-arid grasslands and a view of the mountains
Photo by Tony McLachlan on Unsplash

Large areas are already wild, especially in the drier parts of the world.

Key challenges for rewilding 30% of the planet

Returning a third of the world to nature where nature gets to decide what happens is acceptable if it means the long term survival of humanity and the wellbeing of those alive today. 

Let’s assume for a moment that it is possible to convince the majority that rewilding is essential to save humanity and that everyone is on board to achieve the 30% that the scientists say is necessary.

A magic wand would be nice but the reality is that choices and decisions must be made on a wide range of issues. 

Here are a few of them.

What third will go wild?

The first challenge is to decide which third of the planet is selected for rewilding and who is prepared to give up their territory to achieve this outcome. 

Obviously, the equitable way is to have every jurisdiction give up their proportional share, so whatever territory is claimed by a country, a third of it returns to nature. 

Only that won’t make much sense. 

Take the Netherlands, for example, a small country with a land area of 41,543 km² and a population of 17 million people. Dutch farmers make the Netherlands the second-biggest producer of food on the planet by export value. 

In 2019 the country sent €94.5 billion of agricultural goods including ornamental plants and flowers (€5.8 billion), dairy products and eggs (€4.3 billion), meat (€4.0 billion) and vegetables (€3.5 billion) to external markets.

The Dutch have become incredibly efficient at producing food. 

It would be madness to reduce the third of their landscape back to nature because then we would have to find equally efficient production from other areas, many times more land area would be needed because not everyone grows food as efficiently.

display of Dutch cheeses
Photo by Dana Ward on Unsplash

The Netherlands produced 952,000 metric tons of cheese in 2021 with an expectation of one billion kilograms by 2025.

2% for 30 years

The current rule of thumb for net growth in food production to feed the global population is 2% for 30 years on our current consumption trajectory.  

This estimate means that food availability must increase by 2% per annum across the board to meet the demands of 7.8 billion people increasing in numbers at 8,000 per hour over the next 30 years. Not all of this has to come from growing more food. There are savings in diet, in the supply chain, and especially in reducing food waste, but the reality is that food production will increase.

Simplistically, the reduction of the agricultural area by a third cannot mean that the net amount of food production will change. 

Food will come from the remaining 66% of the production land. Instead of 2% growth, that land will need to produce 4.7% more food per annum each and every year for 30 years. Overall an increase of 140% over the current rates of production.

This is unrealistic.

Already wildland

We will come to the option of changes to diet to reduce demand in a moment but first, we need to consider what is already in use or put aside for nature. 

Land humans find useful for food or fibre production is generally used for that purpose. The fertile land grows crops, the less fertile land grows livestock, and the forests are there for the timber often on soils not suitable for anything else. Equally, we fish the best and the most accessible waters. 

The national parks, reserves, and wilderness areas tend to be on land where it is hard to turn a profit from any of the productive uses. 

On land use criteria, 29% of the land is barren or under glaciers and ice sheets. Does this count towards the rewilding given it is already wild?

infographic that shows the proprtion of global land used for agriculture

If rewilding a third of the landscape applies to the habitable land then forests and shrubland already account for 48% of this area (34% of the total land area).

If rewilding applies to 50% of the habitable land used for agriculture then restoration of 15 million km2 of agricultural land is required.

The problem is that profit is an incredibly powerful force. 

When it comes to the individuals currently owning or managing the land for profit, there will be strong resistance unless it is obvious that profit-making can continue. 

This landscape looks wild already but is actually managed for grazing and timber production. Photo by freddie marriage on Unsplash

Rewilding is a bold concept 

Rewilding is logical and achievable in theory but…  And there tends to be a but when humans are involved because human nature gets in the way. 

One of the reasons humans are so successful is that we are incredibly ruthless. We will do whatever it takes to get what we want. 

Think of the former President of the United States chirping and weaselling his way like you wouldn’t believe, to use any means possible to give himself half a chance of re-election even though he lost. And a lot of people are like that. The desire to win and not to lose is a very powerful emotion.

The middle ground of win-win is the logical solution but always people won’t want to be losers and would like to be winners outright. Think of this from the point of view of a subsistence farmer in Africa or South America where winning means food for themselves and their family. 

Losing their land to rewilding cannot mean the loss of livelihood but also must account for the opportunity cost of losing land including the security that ownership gives to the farmer and his descendants.

The boldness of rewilding is that it must address the social challenge of land as an asset, as security and as a home. 

It must confront and solve the compensation demanded from land given back to nature (opportunity cists) and still give those who live on the land a purpose.

Jurisdiction level choices of rewilding

The choice of whose third it is to rewild could be made across jurisdictions through some sort of international agreement.  

For example, countries could be given an allocation target and meet it by rewilding in-country or paying other countries to put land aside. Something like the market mechanisms for emission reduction could be developed. Countries offering land credits would benefit from the payments and from having nature close to their productive lands. 

Mechanisms to meet targets by trading services would be attractive in the same way that carbon trading was attractive to promote an energy transition away from fossil fuels. 

Obviously, the rules would need to be transparent. 

One of the problems with the carbon trading system was the rules only restricted emissions and sequestration within the jurisdiction. Emissions from economic activity that happened elsewhere did not count. For example, coal-producing nations did not have to count emissions from coal they mined, the country that burnt the coal added those emissions to their national accounts. Australia, an already high emitter per capita, is not required to include the 380 million tonnes of coal exported in 2017/18 in its national carbon accounts.  

The rules of the transaction for rewilding benefits would need to be extremely carefully thought through to avoid similar perverse outcomes. 

History tells us that that’s a hard thing for international agreements to achieve. They are fine with broad statements and audacious goals and targets. But it’s another thing altogether to actually figure out the mechanisms by which those targets could be achieved. 

It is also important to make sure that the wealthy countries do not use the mechanism to keep the poorer countries poor. Rewilding in the poorer countries would need to be adequately compensated with investments in agricultural intensification or the provision of reliable food equity. Perhaps even supply chain access is sufficient to achieve food security and relieve the pressure on subsistence agriculture.

Remember that the wildest places on earth are either unpopulated, places like Siberia, Greenland and the Antarctic, or underdeveloped, such as large parts of Africa. However, the underdeveloped places in Africa and parts of Asia are where population growth is fastest and there is the greatest pressure on land to feed people.

Kate Raworth quote on urbanisation

It is worth remembering that the degradation of nature story has had chapters where international and national targets were set. Only the targets were never met. Most have failed and the few success stories are localized. 

Rewilding through jurisdictional level mechanisms will be very challenging.

Nature on the doorstep

One premise that Sir David was trying to get across in A life on our planet was that nature on your doorstep is actually the answer to most environmental problems. 

Untroubled nature close by integrates the natural habitat into human landscapes in a way that informs and improves both. The sell is that the human landscape becomes more productive and more efficient in the presence of nature. 

Broadly this is the concept of nature delivering ecosystem services

Ecosystem services are attributes of natural and managed systems that through a combination of environment and biology deliver support, provisions, regulation and cultural services to human society.

Sustainably FED has a tutorial on the definition and value of ecosystem services. 

What we need to know here is that rewilding will help to maintain these vital services in landscapes, make them more resilient to disturbance, especially from climate change, and make them more useful for feeding everyone well.

Rewilding will bring these services closer.

It also begs a question of design. Should rewilding be patchy, interspersed with agriculture and the built environment or reestablished in large swathes like a blanket over all the other land use?

There are benefits to both that depend on the objective. If rewilding is about services then an integrated landscape approach would spread benefits to where they are needed. If it is about saving iconic species that typically need large areas of habitat, then blocks of rewilding would be more effective.

And we are back to the value proposition again. What we want to achieve will determine the optimal design.

Back to nature is constrained 

Rewilding cannot return nature to its pristine past. 

Let’s just repeat that… Rewilding cannot return nature to its pristine past.

Once nature has been altered by human disturbance it changes ecosystem structure, composition and function. It is also pushed off any trajectory of change it was already on. 

Rewilding is not as simple as turning the car around and driving back to the garage, that is not how nature works. 

What nature does is respond to the disturbance and react accordingly. Habitats change after a disturbance and develop as a consequence. If rewilding involves re-vegetation then we get what we call regeneration through natural succession or rehabilitation if active management is involved, not restoration to the original. 

Humans are smart but still not sophisticated enough to be able to manipulate ecological succession to achieve the same complex systems that nature developed prior to humanity. There is no way we can get rainforests to look and be as diverse as they were prior to human impact. 

That’s not to say we shouldn’t rewild, it is just that we need to have in our minds rewilding is a return to nature and nature will do what it wants with that process

Nature will regrow vegetation and it will return ecosystem services and begin to rebalance the movement of energy and nutrients through the system. But it has to do it in its own way with organisms and species that it can draw on. It can’t and won’t return to what it was before with mastodons and sabre-tooth cats or wolves, bears and barbary sheep. 

Rewilding also implies multiple-use and a range of values and this is not wilderness. Because rewilded areas will come with some human use of resources.

The pre-1788 problem

Unfortunately, it is a common mistake to assume that humans can repair nature back to the original pre-human condition, a misnomer that is especially common in the conservation movement. 

For example, in Australia, the pre-1788 condition of the vegetation is used as a benchmark, an assumption of what the vegetation was like before Europeans arrived and began to alter the landscape. 

That benchmark is used as a rule and a measure against whether or not a habitat is common or rare or should be protected. 

Attractive as it sounds, there are several problems with this before and after approach.  

First, we only have guestimates of what the landscape was like prior to 1788, the arrival of Europeans. Note not the arrival of humans because that happened at least 70,000 before this date. Vegetation cover, type and composition are only estimated. Comprehensive biological inventories of today’s habitats are absent so we really do not know what was present prior to modern records.

Then there is the landscape change that has happened in the last 230 years as a result of agricultural land use.  Vegetation pattern has changed, soil nutrient levels are different, soil carbon has been lost, the climate is different, the available plants and animals are different. There is no way that nature could return to what it was. 

Consider the nutrient consequences of billions of sheep reared on native vegetation across outback Australia. The fleeces and meat from those animals were extracted from the habitat and sent to Europe, net export of nutrients, especially nitrogen. 

Nature in the wild will be different from what it was pre-human impact. 

Rewilding is really just turning to wild. It doesn’t mean returning to a previous prescribed condition because that will simply be sending us out of the frying pan into the fire.

closeup of part of a herd of sheep
Photo by Sean Thoman on Unsplash

There were 66 million sheep in Australia in 2019, that’s 2.6 sheep per person.

More policy problems

Rewilding is emotional and political. 

Environmental legislation has a traditional focus on in situ conservation and the preservation of historical conditions, which have favoured the implementation of conservation projects aiming to restore previously observed benchmarks

Pettorelli et al 2018 

Public policy is pushed towards preservation. It comes from the human condition that is attracted to stability and certainty and avoids change. Politicians leverage this by telling people that historical conditions can be preserved be that a species, a habitat or a historical building.

But the reality is that the changes that happen as a result of human use of nature push ecosystems to their limits and species out of their tolerance replacing them with novel ecosystems. 

Agriculture is the primary human use of nature. It uses the most land and water, changes vegetation and depletes soils. It is also essential to feed everyone well.

These two areas of policy, preservation wrapped up these days into biodiversity policy, and food production or land use policy are often at odds.

For example, in the European Union, the current biodiversity policy is based on a “compositionalist” paradigm, predicated on the preservation of particular species assemblages and habitat types often with strong legislation in member states that defines targets for species and habitat protection. 

Meanwhile the Common Agricultural Policy (CAP) keeps marginal lands in agricultural production through agricultural support payments. Plus 70% of payments under the CAP require that land is in “good agricultural condition” and free of “ineligible features” such as naturally regenerating scrub.

Back in NSW the Crown Land Management Act 2016 gives permission for a lease holder to occupy and use Crown land for a specified purpose such as grazing. A Land Management Strategy submitted as part of the licence application creates the obligation that the licensed area is grazed in accordance with this plan. In other words, keep grazing.

Rewilding is at odds with both land use and biodiversity policies.

infographic showing overlap of policy

Rewilding (has) framed itself as fundamentally contrary to the assumptions about equilibrium ecosystem dynamics and cultural landscapes at the core of the EU’s policy approach

Root-Bernstein et al 2019 

There are paradigm shifts to consider in the practicalities of rewilding. 

We may be able to restore certain iconic species as has been happening in northern Europe and the US around wolves and bears to bring those iconic species back into ecosystems, but those returning species are living in habitats very different to the ones that their ancestors lived in. There’s nothing wrong with this at all. It just needs to be accepted as the way that rewilding will work. 

two young men collecting litter on a beach
Photo by OCG Saving The Ocean on Unsplash

Rewilding also requires a massive clean up job.

Rewilding in practice

In practice, rewilding projects are a multiplicity of things, responding to site history, social context, geography, ecological condition, and feasibility in both physical (how do we move that animal?) and legal senses (are we permitted to move that animal?)

Root-Bernstein et al 2019 

Shifting paradigms is challenging but so too are the practicalities.  Removal of human activity from a region or an area and then letting nature recover will be the smartest and cheapest option for vegetation and soil to return to the wild. 

Nature is extraordinarily good at exploiting a resource and left alone organisms will come in and use whatever space is available. 

One of the challenges we have though is that rewilding must be as fast as possible. The premise of rewilding is not just to return to nature that is resilient and able to recycle nutrients and energy efficiency without mining natural resources. This has to happen fast.

There are two key reasons for this.

The first is that rewilding will only work if there are multi-use systems. Some of the biomass still has to feed humans and it will be hard to do this whilst rewilding is happening, but a little easier when nature is back in balance.

The second reason is that we want rewilding to help with other environmental issues, especially climate and water management.  For example, in order to prevent some of the spiralling sequences that will accelerate global warming, carbon dioxide in the atmosphere must be sucked down as fast as possible into vegetation and soil. In some habitats, the level of change that humans have wrought is such that the habitats are barren. Any recovery that nature might deliver will be slow.

Rewilding in such cases must be a very active process and may not be possible at all. The technical details of how to speed up and give nature a lift. And where we need to intervene because nature would otherwise take a long time to reverse the damage to the soil and vegetation. 

Active management introduces two additional challenges: cost and choice.

What exactly should the active intervention be? Planting, weeding, fertilizer use, irrigation, flood control, animal reintroduction, fire management and a host of tactic choice’s around these broad strategies.

Is there experience enough to make the right choice and expertise enough to implement them? And who pays for this activity? 

Whatever the objective, rewilding will cost money and require experts to help make management choices and skilled practitioners to deliver active management on the ground.

In the practice of rewilding there will be capability and capacity shortages.

farmer preparing the land for planting
Photo by Visual Karsa on Unsplash

Farmers have critical local knowledge of how to manage nature.

Regenerative agriculture

Rewilding is a bold option because the requirement to feed 7.7 billion people and their pets is an unwavering imperative—the size of the ‘feeding everyone well’ task is roughly 23 trillion kilocalories per day, each and every day for at least 100 years.

Current modes of food production are a combination of small-scale subsistence farming practised by the majority of farmers around the world. The farmer produces enough food for himself and his family and not much excess. 

The other method of production is from a small number of farmers who produce intensively over large areas. They grow food for profit with significant inputs of energy and nutrients. These farms provide the majority of the food eaten by people around the world who are not farmers, including the three and a half billion or so people who live in towns and cities. 

We can rewild both of these production systems by converging somewhere in the middle through various combinations of regenerative agriculture

The principle is to have multiple crops maintained in closed-loop nutrient systems, in other words, to keep the nutrients within the landholding as much as possible. And have patterns of production that use plants and animals to operate more like an ecological system and less like an input-output system. 

Conversion of the majority of our agricultural land to these practices will have a terrific influence on landscape properties. It will improve the attributes of landscapes that will help the rewilding process. It will make agricultural land attractive to a wide range of organisms, much more so than currently. Critically it will maintain soil biodiversity and enhance biological activity in the soil. 

And whilst it might not be truly wild in the way that Sir David would like it to be, it does provide habitat for a wide range of wild animals and plants. 

In other words, we have to change our approaches to agriculture, the subsistence approach and the intensification approach to effectively achieve rewilding. 

We can treat them as two separate things in a way because they present very different sets of challenges. Obviously, the subsistence agriculture system is driven by a person’s need to provide themselves with food and fiber for their families—recall that 4 billion people live on less than US$5.50 a day. 

In other words, half the world is not really operating in a cash based system. You can’t live on five dollars a day unless you’re growing a huge chunk of your own food. 

What sustainably FED suggests

Audacity has great value and rewilding a third of the planet is audacious.The sort of grand, far-sighted action that can galvanise and gather people together.

In 1961, when the world was struggling with east-west brinkmanship in the cold war, U.S. President John F. Kennedy proposed an audacious national goal “before this decade is out, of landing a man on the Moon and returning him safely to the Earth.”

Audacious barely describes such a call. 

The USSR had only just put the first man in space, computers were in their infancy, communications were limited and the moon was a long way away. Imagine the details needed to get that job done. It also shifted the rhetoric from nuclear armageddon to human achievement.

There are huge challenges to returning a third of the planet back to nature and still feeding all the people. It is a much harder task that putting a man on the moon and bringing him back safely. But think how hard that was. The guidance computer on board Apollo 11 was puny—your mobile phone has millions of times more memory and processing power.

Rewilding is even more audacious and maybe that is its strength. 

As Landres et al (2020 point out ‘it compels public debate and collaborative discussions leading to revised agency policies to guide consistent and appropriate management direction’. 

Rewilding is emotional and needs a change in mindset. The practicalities are complex and often conflicting values have to mesh. 

It sounds crazy but rewilding 30% of the planet might just be the answer to human sustainability.

Science sources

This review draws heavily on excellent research contributions from 

  • du Toit, J. T., & Pettorelli, N. (2019). The differences between rewilding and restoring an ecologically degraded landscape. Journal of Applied Ecology, 56(11), 2467-2471.
  • Landres, P., Hahn, B. A., Biber, E., & Spencer, D. T. (2020). Protected area stewardship in the Anthropocene: integrating science, law, and ethics to evaluate proposals for ecological restoration in wilderness. Restoration Ecology, 28(2), 315-327.
  • Pettorelli, N., Barlow, J., Stephens, P. A., Durant, S. M., Connor, B., Schulte to Bühne, H., … & du Toit, J. T. (2018). Making rewilding fit for policy. Journal of Applied Ecology, 55(3), 1114-1125.
  • Root-Bernstein, M., Gooden, J., & Boyes, A. (2018). Rewilding in practice: Projects and policy. Geoforum, 97, 292-304.

Hero image modified from photo by Marissa&Eric on Unsplash


Mark is an ecology nerd who was cursed with an entrepreneurial gene and a big picture view making him a rare beast, uncomfortable in the ivory towers and the disconnected silos of the public service. Despite this he has made it through a 40+ year career as a scientist and for some unknown reason still likes to read scientific papers.

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