Forests get most of the attention when it comes to nature-based climate solutions — but what about the animals that inhabit them? As rewilding efforts gain momentum globally, the science linking healthy wildlife populations to carbon storage and ecosystem health — the basis for the Animating the Carbon Cycle platform, developed by Professor Oswald Schmitz, the Oastler Professor of Population and Community Ecology, and the Global Rewilding Alliance — is growing more robust. Schmitz recently spoke with YSE News about how animals actively shape soil carbon, what it takes to find the right balance of wildlife on the land, and why the climate accounting most governments rely on is still missing a critical piece.
Q: To get started, let’s talk soil. Specifically, could you explain how the presence or movement of herd animals over the land can impact soil carbon levels?
First, we need to appreciate that soil is the foundation for all terrestrial life. Without soil, there would be no plants, without plants there would be no animals. Animals, however, are active participants in this cycle, not just beneficiaries of it. As they forage and move across landscapes, they spread their body wastes. Urinary releases to the soil enhance soil fertility, which can promote plant productivity (carbon capture). Release of dung increases soil organic carbon and helps build soil structure that improves water filtration and soil aeration. Animals may also compact the soil by trampling, which enhances the long-term stability of that stored carbon
Q: In the past, you’ve spoken about the sweet spot in herbivore population size on the land. What does that mean, and how do you determine that sweet spot?
The instinct is to think more is better — that the more we rewild animal populations, the more we improve ecosystem health. But too few individuals mean their functional roles, like improving soil, go unrealized across vast areas. Too many leads to soil erosion from heavy trampling or reduced plant diversity from intensive foraging.
In nature, ecological processes tend to reconcile these extremes, converging on population sizes that sustain ecosystem health long-term — the sweet spot. Our heavily managed world disrupts these natural processes, so the challenge is to scientifically identify that sweet spot for any given mix of rewilded species. Mathematical ecosystem modeling can estimate it, and those estimates then guide field tests where population sizes are adjusted and ecosystem responses measured.
Q: Animating the Carbon Cycle, which provides estimates of the carbon drawdown potential of healthy wildlife populations and restored ecosystems, launched in 2024. Is there anything that’s surprised you about how the platform is being used or who’s been using it?
The science now coined Animating the Carbon Cycle (ACC) formally began decades ago. In the interim, enough scientific evidence has amassed to support promoting ACC as a potential nature-based solution that can mitigate biodiversity loss and global climate change together. The ACC platform, developed by the Global Rewilding Alliance in 2024, presents the available scientific evidence to the broader public in a highly accessible way.
What has surprised me is how rapidly it has inspired enthusiasm in both the grassroots and international wildlife conservation NGO community globally, while less so in government environmental agencies. Moreover, while ACC is a highly captivating way to promote animal conservation, especially of large charismatic animals, members of the NGO community that I work with are committed to thoughtfully ground their advocacy using the best scientific evidence. It is gratifying to see the science-practice partnership embraced here to ensure that ACC is not uncritically promoted as the next environmental cure-all.
Q: What are some of the obstacles or challenges to rewilding efforts? Are they different in wealthier nations versus lower-emitting countries?
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The challenges are not unique to wealthier versus low-emitting countries. Rewilding is universally about returning species to their historical landscapes, often outside of protected areas, into places where generations of local human communities have not experienced them. Thus, successfully rewilding animals anywhere requires first working with local communities to understand their values, attitudes, desires and concerns about returning an unfamiliar animal species. When rewilding is considered acceptable by communities, the conservation goal becomes creatively working with those communities to devise acceptable ways to coexist with rewilded species. At a minimum, this involves anticipating and addressing the risks of human-wildlife conflicts that bear upon human safety and livelihoods well before any animals are rewilded.
Q: How would you like to see this work evolve — both in terms of advancing research at the intersection of rewilding and carbon storage and real-world rewilding efforts?
One of the challenges for US-based scientists is getting federal government funding to do research on biodiversity and on ecosystem processes that mitigate climate change —especially internationally. However, the science-practice partnerships that I mentioned earlier are helping to address the funding void. It is a great model for research that I’d like to see expanded. This is because through rewilding the practitioner community is effectively creating the “experiments.” As scientists, we can leverage those animal reintroductions and through modeling and measurement build a deeper scientific knowledge base about the role of animals in ecosystems. It is a wonderful way to learn by doing.
As the science matures, I hope it will increasingly inform how governments account for nature's role in climate mitigation. The Paris Climate Agreement requires signatory countries to submit biennial emissions reports called Nationally Determined Contributions (NDCs), which typically cover sectors like transportation, agriculture, and energy, with little accounting for nature beyond forest restoration. Yet animals can significantly enhance emissions reductions — sometimes matching smaller sectors and reaching 10–15% of larger ones — and they exist in every ecosystem, not just forests. Most governments are failing to appreciate what nature contributes to their NDCs. It would be great to see more and better accounting of nature’s contributions. These climate solutions currently remain hidden in plain sight.
