Great wildebeest migration crossing Mara river at Serengeti National Park – Tanzania, Jorge Tung, Unsplash
Involving the movement of over one million animals, the annual wildebeest migration across East Africa’s vast Serengeti grassland is one of the world’s most awe-inspiring natural spectacles. It’s hard to imagine such a herbivorous horde disappearing from the landscape. But this nearly happened in the first half of the twentieth century, when poaching and disease (the rinderpest virus) saw wildebeest numbers plummet to around 300,000.
The consequences of this collapse were profound. Much of the 25,000 square- kilometre Serengeti ecosystem was left ungrazed. The dead and dried grass that accumulated as a result became fuel for massive wildfires, which annually ravaged up to 80 percent of the area, making Kenya and Tanzania a significant regional source of CO2 emissions. Over many years this state change also led to the loss of organic carbon from soil carbon stocks, as the entire Serengeti ecosystem became a net carbon source.
The situation changed in the late 1950s when a rinderpest vaccine eventually became available, leading to the effective eradication of the disease. This, combined with anti-poaching measures, saw the wildebeest population gradually recover to natural levels. More animals meant more grazing, which saw carbon shifted from above-ground combustible biomass to the soil via dung, thereby promoting carbon storage and reducing the incidence of wildfire.
Every time the wildebeest population increased by 100,000 animals, the area being burned reduced by around 10 percent. More trees grew, storing more carbon.
Wildebeest migration Serengeti, Helena Pfisterer, Unsplash
Protecting Wildebeest in Serengeti can sequester 4.4 MtCO2 per year. That’s 28% of the total fossil fuel emissions by Tanzania in 2021 (13 MtCO2/y) ¹
It shows how the loss of just a single species can have far-reaching implications for ecosystems and climate.
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Wildebeest infographic based on oroginal design by GRID-Arendal
How do wildebeest help store carbon?
- Grazing Reduces Wildfires: When wildebeest populations recovered, their grazing reduced the accumulation of dead, dry grass, which was previously fueling massive wildfires. As fewer fires occurred, carbon release into the atmosphere diminished significantly.
- Dung Promotes Soil Carbon Storage: Wildebeest deposit organic matter through their dung, which enriches the soil and promotes carbon sequestration by transferring carbon from plant biomass into the ground.
- Supporting Tree Growth: With fewer fires and healthy grazing patterns, trees began to regrow in the Serengeti, further contributing to carbon storage through increased biomass.
- Ecosystem Balance: By maintaining the health of the Serengeti ecosystem, wildebeest support a balanced food chain, which has ripple effects on other species and processes that help long-term carbon storage.
Current situation – what we need to do
Today, the impact of the restored wildebeest population on the Serengeti landscape means there are almost no wildfire outbreaks at all, while the rejuvenated grasslands now capture carbon up to the equivalent of the annual anthropogenic CO2 emissions of Kenya and Tanzania combined. The Serengeti has become a carbon sink once again.
The case of the wildebeest in the Serengeti is just one example of how animals, and their presence or absence in a particular ecosystem, can impact the capacity of that ecosystem to store carbon. It also shows how the loss of just a single species can have far-reaching implications for ecosystems and climate. By being an integral part of a larger food chain – as wildebeest are – the presence or absence of such species may trigger knock-on effects that grow through the chain to drive significant amounts of carbon into long-term storage on land or in the ocean, or release it into the atmosphere.
(1) Note: These species data are from Table 1 and the Supplementary Appendix 1 of Schmitz, O.J., Sylvén, M., Atwood, T.B. et al. Trophic rewilding can expand natural climate solutions. Nat. Clim. Chang. 13, 324–333 (2023). https://doi.org/10.1038/s41558-023-01631-6
Next steps
- Return to the main Climate Heroes page.
- Read all the original Climate Hero case studies in ‘Animating the Carbon Cycle: Supercharging Ecosystem Carbon Sinks to Meet the 1.5°C Climate Target’. Download the pdf here.
- Curious to learn more? Watch the video from the UN Climate Change Side Events at COP28: Bringing elephants into the room – why UNFCCC needs to put animals on the table.