Photo detail / credit: Indian One Horned Rhinoceros, Kaziranga National Park Assam, Sanctuary Asia – Sumon Das

Animating the Carbon Cycle (ACC) is the
new scientific field that studies the role of animals in enabling carbon drawdown
The new Yale/GRA ACC model, developed at Yale School of Environment with support from the Global Rewilding Alliance, can characterise and quantify the effects that animals (both carnivores and herbivores) can have on ecosystem carbon budgets.
THE CRISIS WE FACE
We are in the midst of a planetary emergency.
Despite the Paris Climate Agreement, our current actions to reach net-zero emission are crucial but insufficient to cap global warming at 1.5°C.
The challenge we face began around 250 years ago with the Industrial Revolution. As we burned fossil fuels to power economic development, CO2 levels in the atmosphere drastically increased, creating what is now known as legacy carbon dioxide.
To meet current climate goals, we must not only reduce further emissions but also draw down and store 500 Gigatons of this legacy carbon dioxide by 2100. If we don’t, we will overshoot the 2°C threshold and risk catastrophic climate heating.
Deforestation, unsustainable industrial forestry, overfishing, bottom trawling, pollution, the continued decline of wildlife populations, and the growing impact of climate change are among the key threats to the very fabric of life on Earth and the ecosystem services we all depend on. Currently, only about 3% of land and sea remains ecologically functional.
Only a dual response, tackling both crises simultaneously through reducing key threats and introducing nature-based solutions, can turn the tide
This dual crisis – climate change and biodiversity loss – demands urgent, comprehensive solutions.
PROTECTING AND RESTORING POPULATIONS of just 9 wildlife species means 6.4 BILLION TONNES OF CARBON DIOXIDE are drawn down annually…
That’s the entire annual carbon emissions¹ of the UNITED STATES!
1 – Emissions according to CO2 country profile on ourworldindata.org
WHAT ARE WE MISSING?

Photo detail / credit: Muskox Norway
– Marc Eggert Unsplash
THE KEY ROLE OF WILD ANIMALS
We must start recognising and supporting the vital role wildlife plays in enhancing natural carbon sinks and boosting nature’s ability to absorb CO2.
Technological solutions alone are not enough to prevent a 1.5 – 2°C rise in global temperatures due to the significant amount of legacy carbon already present in the atmosphere.
Scientific research shows that restoring wildlife populations is crucial in drawing down legacy carbon and creating negative emissions. Healthy wildlife populations help ecosystems store more carbon, creating a balanced ecosystem for people and nature and building climate resilience.
Rewilding efforts and the protection of key ecosystems contribute to two of the IPCC’s top mitigation strategies for cutting net emissions by 2030:
- Reducing the conversion of natural ecosystems (4.0 GtCO2-eq/y), and
- Restoring, afforesting, and reforesting ecosystems (2.8 GtCO2-eq/y)
This is what we call Animating the Carbon Cycle (ACC), a nature-based climate solution that simultaneously addresses both the climate and biodiversity crises.
We cannot meet the 1.5-2° C target without wildlife as part of the solution
“If we think about ecosystems as skeletons, animals and species that inhabit them are the organs. Logically, no skeleton can fully function without organs present.”
Dr. Reem Al Mealla, CEO Nuwat
WILDLIFE SPECIES PROVIDE NATURAL CLIMATE SOLUTIONS by controlling ecosystem carbon cycling in two general ways
1
Protect the carbon already stored in nature from being released
2
Help nature draw down and store even more carbon
Most carbon cycle models currently focus only on plants and microbes, which can lead to inaccurate estimates of carbon storage. Animating the Carbon Cycle (ACC) shows that animals play a crucial role in ecosystems by helping plants capture carbon and allowing soils to store it. Including animals provides a more accurate understanding of how carbon is cycled in ecosystems.
COST-EFFICIENT
RAPID
SCALABLE
ANIMATING THE CARBON CYCLE THROUGH REWILDING:
The policy that addresses both climate & biodiversity crises

Photo detail / credit: Wild cat release
– Felinos do Aguai
THE ROLE OF ANIMALS IN THE CARBON CYCLE
Trophic rewilding involves reintroducing species to restore top-down interactions within ecosystems, boosting biodiversity, ecosystem resilience, and ecosystem services such as preventing fire, flood and drought, and increasing carbon storage
CONNECTED ECOSYSTEMS: The ripple effect of every species

Photo detail / credit: Rewilding Chile,
Cristian Saucedo
HERBIVORES:
Natures Gardeners
- Herbivores, through trampling and grazing maintain low vegetation levels to reduce wildfire risks.
- Grazing animals trample snow and prevent permafrost thawing.
- They enhanced soil carbon storage.
- They also spread seeds, recycle nutrients, fertilise the soil, and maintain a diverse mosaic of habitats.

Photo detail / credit: Brown bear, Finland
– Grégoire Dubois
CARNIVORES:
Ecosystem Balancers
- Carnivores control herbivore populations, maintaining ecosystem balance.
- Without predators, herbivore numbers increase, leading to overgrazing, and reducing the ecosystem’s ability to absorb carbon.
- Carnivores also influence how herbivores move through the landscape. To avoid predation, herbivores concentrate in certain areas and avoid others, allowing shrubs, trees, and seagrasses to thrive in less-grazed areas. This process, known as “landscapes (or seascapes) of fear,” enhances carbon capture in those regions.

Photo detail / credit: Whale
– Jorge Vasconez on Unsplash
MARINE ANIMALS:
Ocean Nutrient Engineers
- Whales and fish move nutrients from deep waters to the surface.
- This nutrient movement boosts phytoplankton blooms, which absorb CO2 from the water.
- Fish and marine mammals also store carbon in their skeletons, which mostly sinks to the bottom when they die and is permanently stored.
SPOTLIGHT ON DIFFERENT ECOSYSTEMS
Click on the different ecosystems to better understand the role wildlife has on carbon capture and storage.


GRASSLAND
Photo detail / credit: Grassland
– Adrien Olichon on Unsplash


ARCTIC
TUNDRA
Photo detail / credit: Tundra, Norway
– Marc Eggert on Unsplash


BOREAL
FOREST
Photo detail / credit: Boreal forest
– Bryce Evans on Unsplash


MARINE COASTAL
& DEEP OCEAN
Photo detail / credit: Brown coral reef
– Kristin Hoel on Unsplash
ACC and REWILDING
Rewilding provides the most effective, long-term nature-based climate solutions by removing surplus carbon generated by humans since the Industrial Revolution from the atmosphere and rebuilding ecosystems’ resilience against floods, droughts, and wildfires.
Collaboration with local and Indigenous communities is a key principle in the success of rewilding. This approach not only strengthens climate resilience but also fosters new opportunities for local livelihoods and sustainable economic growth, ensuring a healthier, more secure future for all.
Photo detail / credit: Patagonia National Park – Rewilding Chile, Jan Vincent Kleine
DISCOVER MORE
The impact of ACC
The Yale/GRA ACC model is already being appliedwith impressive results.
Get involved
Whatever your area of interest, you can help support this important work.
Who’s behind ACC
Find out more about the team behind the Yale/GRA ACC model.
SCIENTISTS & ORGANISATIONS BEHIND

This initiative is led by a partnership between the Global Rewilding Alliance and Yale School of the Environment.
This work would not have been possible without our Rewilding Champions. A great thank you to:
Biophilia Foundation, Rewilding Europe, Rewilding Chile, IFAW, André Hoffmann, Ben Goldsmith, Re:wild. We also want to thank One Earth and the WILD Foundation for helping us get started on his important initiative.
Together, this coalition advocates a very clear solution: preserving intact nature and immediately restoring and rewilding functional ecosystems at landscape and seascape scale. You can find out more about us here.