This post is an excerpt from Oliver TUFFT's column in newspaper The Climate.
A new study published last month shows that protecting and restoring wild animals can enhance natural carbon capture and storage.
Rewilding is largely seen as a novel approach to conservation and a symbol of hope. Most proponents support the theory because it helps restore the complex web of life on which all living beings, including Homo sapiens, rely. Now, a study published in Nature Climate Change has found that rewilding improves the carbon-capturing abilities of landscapes where key animals, and their ecosystem functions, are present.
When we talk about sequestering carbon, we are generally talking about two approaches. The first is carbon capture, and the second is referred to as natural climate solutions.
Typically, natural climate solutions seek to remove carbon by restoring ecosystems, allowing plants and soil, among other things, to sequester carbon and store it in organic matter. Until now, these kinds of solutions have been viewed as having the corollary benefit of promoting biodiversity, as by restoring ecosystems we create habitats for animals.
However, this reasoning undermines the role that animals play within the complex world of the carbon cycle and ecosystems themselves. Often referred to as ‘animating the carbon cycle’ (ACC), landscapes and the animals that live within them have a joint effect on the functioning of ecosystems and the carbon they can store. Flora needs Fauna.
It is easy to understand the prevailing view that restoring ecosystems would attract wildlife only as a secondary benefit. Many scientists used to believe that landscapes evolved over time and that animals tended towards those landscapes that suited their particular needs. In this sense, landscapes evolved independently of animals and would flourish with or without them.
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However, we now understand that landscapes and the animals that live within them evolved together, as explained in Rewilding: The Radical New Science of Ecological Recovery (by Paul Jepson and Cain Blythe).
Animals influence the ecology of a landscape just as much as landscapes influence the diversity of animals that live within them. Over time these landscapes evolved to survive and function in the presence of animals — so much so that many landscapes require animals to function properly.
Co-authored by 15 scientists from eight countries, the paper, titled Trophic rewilding can expand natural climate solutions, now provides data for what the early adopters of rewilding have been expounding and gives credence to the idea that in order to save the world, we need to rewild it.
Trophic rewilding centres around restoring and protecting the functional roles of animals in ecosystems and is an often overlooked climate solution — according to this report, however, it shouldn’t be.
To limit global temperature rises to 2°C above pre-industrial levels, as stipulated under the Paris Agreement, we must remove and store 500 gigatonnes of CO2 between now and 2100 (or 6.5 gigatonnes per year). According to the report, rewilding just nine species or species groups (African forest elephants, American bison, fish, grey wolves, musk oxen, sea otters, sharks, whales and wildebeest) would contribute more than 95% of this annual requirement.
Speaking to Mongabay, the paper’s lead author Oswald Schmitz, a professor at the Yale School of the Environment, spoke of the significance of trophic rewilding as a climate solution, highlighting that the “numbers rival those of what the IPCC [Intergovernmental Panel on Climate Change] is right now promoting in terms of converting everything to solar or wind generation.”
Natural climate solutions typically focus on protecting and restoring plants and soils (e.g., tree planting), but what this research shows is that animals have an important impact on how effective these carbon sinks can be.
In light of what is now understood about the relationships between ecosystems and their inhabitants, natural climate solutions seriously limit their own potential. In order to unlock the potential for increased negative emissions, we should start viewing animals and plants, fauna and flora, as functionally interdependent.
“Wild animals cause a 15-250% difference in the amounts of carbon stored in plants and soils.”
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By now many people have heard about how the wolves of Yellowstone are restoring rivers or about how whales are the world’s biggest biological nutrient pump. While not all animals have such key ecosystem roles or attract such major headlines, all animals have a part to play. Indeed, the paper highlights that while “wild animals contain only 0.3% of the carbon held in the biomass globally [...] many could nonetheless exert outsized control by causing a 15–250% difference in the amounts of carbon in plants, soils and sediments relative to the conditions in which they are absent.”
Not every animal is suited to every climate, though there are many candidates for species with high potential to enhance carbon storage in specific ecosystems. For example, wolves instil fear in herbivorous prey animals in boreal forests, ensuring they cannot stay in one place and overgraze areas, wildebeest transport nutrients from where they’ve grazed to where they excrete and muskox encourage grasslands, which improves solar reflection and prevents the carbon-rich permafrost from thawing and releasing massive amounts of greenhouse gases.
“Perhaps we should have listened to Mother Nature in the first place.”
The research makes clear the benefits of trophic rewilding, although its implementation at a global scale is a problem that remains to be solved.
“The science is not yet robust enough and the timescales involved in many cases are too slow given the urgency of the climate crisis,” Yadvinder Malhi, an ecosystem science professor at the University of Oxford, who was not involved with the research, told New Scientist. “Trying to get this into international climate frameworks could even be a distraction from the only real global warming game changer, which is keeping fossil fuels in the ground.”
So, while it may not be a quick fix for climate change, it is hoped that with more research rewilding can move from being a relatively niche novel theory to being a serious contender in our toolbox of natural climate solutions. As well as providing huge benefits in terms of carbon sequestration, a more mainstream uptake of rewilding would provide serious benefits on the individual and community level, from a greater sense of wellbeing and connection with nature to a cure for rural depopulation.
In any case, exceptional circumstances, like the one Homo sapiens finds itself in today, require exceptional solutions. Perhaps we’ve been putting too much faith in our own intelligence. Perhaps, we should have listened to Mother Nature in the first place. As more and more of us adopt rewilding, we’re finally starting to listen.