Herd of 170 Bison Can Store CO2 Emissions Equivalent to 40,000 Cars; How Do These Bovines Help in the Fight Against Climate Change?

Bison are large, horned ox-like animals of the Bovidae family which is considered as the most diverse group of hoofed mammals. The majority of bison in the world are raised for human consumption, especially by Indigenous people in North America. They are also a good source of fur clothing.

In a recent study, it was found that this large herbivore does not only benefit humans but the entire planet as well.

Rewilding Project

More than two centuries ago, European bison disappeared from Romania. In 2014, Rewilding Europe and World Wildlife Fund (WWF) Romania reintroduced the bovine species to the southern Carpathian mountains.

Since then, over 100 bison were given new homes in the foothills of Tarcu mountains. Today, they grew to more than 170 animals, one of the largest free-roaming animal populations in Europe. It is expected to grow even larger since the landscape can potentially hold 350-450 bison.

A decade after the rewilding project, experts are observing how the bison help transform the ecology of the region, providing a glimpse of hope into the fight against climate change. In the paper "Rewiring the Carbon Cycle: A Theoretical Framework for Animal-Driven Ecosystem Carbon Sequestration," the research team used a new model to calculate the additional amount of atmospheric carbon dioxide captured and stored in soils. Wildlife animals help trap CO2 through their interactions within ecosystems.

The study reinforces the consensus that large mammals play a vital role in the carbon cycle. Rewilding efforts can be key tools in addressing the intertwined biodiversity and climate crises. Further studies are needed to validate the models and understand how long it would take for bison benefits to accrue.

The researchers also looked at nine species, such as sea otters, musk oxen, and tropical forest elephants. Many of them show similar promise to the bison, doubling the capacity of the ecosystem to draw down and store carbon.

Beefy Climate Heroes

In the Tarcu mountains, the European bison herd graze in an area of almost 19 square miles (50 square kilometers) of grasslands. This allows the bovines to capture an additional 54,000 tonnes of carbon a year. This rate is almost 9.8 times more carbon than in an ecosystem without the bison, although the experts noted that the figure could be 55% higher or lower.

This corresponds to the annual carbon dioxide released by 43,000 average petrol cars in the US, or 84,000 in the higher figure. It is also equivalent to a median of 123,000 average European cars which have higher energy efficiency.

According to lead author Prof. Osward Schmitz, bison affect grassland and forest ecosystems by evenly grazing grasslands, dispersing seeds to enrich the ecosystem, recycling nutrients to fertilize the soil, and compacting the soil to prevent the release of stored carbon.

The removal of bison in the grassland and forest ecosystems led to the release of stored carbon in the soil. As the researchers noted, rewilding bison is one of the best ways to restore balance in these ecosystems. They can be a nature-based climate solution with major biodiversity conservation co-benefits.