In 1995, Yellowstone National Park reintroduced grey wolves for the first time since they were killed off in the park in the 1930s. After their reintroduction, a series of incredible changes occurred in the park that saw beaver colonies – which had previously died down to a single colony left in the park – rebound and flourish, and an entire river change its course. 

How could the presence of wolves change the path of a river? The answer is found in an increasingly talked about solution to biodiversity loss and carbon emissions: rewilding. 

What is rewilding? 

Rewilding is the process of restoring land and ecosystems to the point where they can flourish without human intervention. Its aim is to create self-regulating and self-sustaining wilderness areas which will maintain themselves without the need for future human intervention. 

And it’s becoming increasingly present in mainstream discussions about how to address our climate crisis and loss of biodiversity, with key environmental leaders like David Attenborough bringing it to the global stage: “To restore stability to our planet we must restore its biodiversity, the very thing that we’ve removed. We must rewild the world.” 

Rewilding is an ever-evolving practice that is characterised by the individuals, ecosystems and landscapes in which it takes place. Each rewilding project is unique, but the central mission remains the same: to reinstate natural processes and where appropriate, re-introduce or revive missing species – allowing them to shape the landscape and habitats from within. 

How does it work in practice?

When the wolf died out in Yellowstone, elk populations – previously preyed upon by the wolves – thrived perhaps too well. 

Their large numbers and lack of need to move across the landscape to escape predators meant that they overgrazed on willow stands along the riverbank, a key source of food for beaver populations. Beaver numbers declined, and the absence of their damming altered and degraded the river as a result.

Reintroducing wolves to Yellowstone resulted in what is known as a trophic cascade: powerful indirect interactions between species that rebalance an entire ecosystem. 

A single species reintroduction therefore altered an entire ecosystem, and is a now celebrated rewilding success story. But not all rewilding projects need to be so dramatic in order to have a significant impact; individual gardens that are left to grow wild with wildflowers and water sources can also have a huge benefit to entire ecosystems. “Creating a pond, or letting some lawn transform into a wildflower meadow, will bring new species into your world,” Rewilding Britain comments. 

What are the main benefits?

• Carbon capture 

Rewilding Britain has calculated that restoring and protecting native woodland, peat bogs, heaths and species-rich grasslands over a total of six million hectares could sequester 47 million tonnes of CO2 per year – more than a tenth of current UK greenhouse gas emissions. 

Similarly, scientists in Brazil have found that returning 30% of farmland in key areas around the world would remove 465 gigatonnes of carbon dioxide from the atmosphere – “almost half of the total rise in this greenhouse gas since the Industrial Revolution.” By allowing ecosystems like forests, woodland and wetland to flourish, rewilding is contributing towards the race to reach net zero and achieve global decarbonisation.

• Reversing biodiversity loss

With the WEF’s latest global risk report citing biodiversity loss as one of the three biggest risks over the next ten years, people are waking up to the connection between our own futures and flourishing biodiversity on our planet. 

Rewilding presents an opportunity to move away from an intensive struggle to fend off rising levels of extinction through conservation efforts alone, and instead aims for a future where entire ecosystems function naturally. By creating pockets of key rewilded areas, rewilding can connect a mosaic of nature-rich habitats which drive wildlife to migrate and adapt to new areas. 

• Preventing floods

Rewilded areas allow the land to absorb more water, reduce peak water volumes & slow run-off from hills. If used in conjunction with existing flood defence systems, rewilding acts as a cheaper and more sustainable form of mitigating the disastrous social and economic damages of flooding. 

• Improves our health and wellbeing

Increased biodiversity and healthier ecosystems are better for both people and planet, providing us with cleaner water, breathable air and better health. Our dissociation from the natural environment has had lasting effects on both our mental and physical health, while increased time spent in nature has been proven to have numerous psychological benefits, such as reducing loneliness, anxiety and depression. 

What are some of the criticisms?

• Controversy of reintroducing dangerous predators

Rewilding is dependent on the restoration of natural processes, including the revival of native predator systems. One method of rewilding an ecosystem is to reintroduce carnivores like bears, wolves and lynx to landscapes where they used to be native. However, there are ongoing debates about managing their return – especially for farmers and members of the general public who have safety concerns. 

•  Practicality of transforming arable land into rewilding projects

With the global population increasing and 38% of the global land surface being used for agricultural production, some critics disregard rewilding projects as a viable large-scale solution.

While there are concerns about the scale and application of rewilding, there are also enormous achievements that have already been seen in both large and small-scale rewilding projects. The flexibility of rewilding allows each project to be guided by the needs of the land and communities around it. The development of rewilding projects will build a nature-rich mosaic of habitats connecting species and engaging people across the globe – and it’s a solution that can benefit all of us.