By digging up carbon trapped in the soil, wild pigs release equivalent amounts of carbon dioxide into the atmosphere every year as over a million cars. The study was published in Global Change Biology by an international collaboration of researchers from the US, Australia, and New Zealand.
Most of the Earth’s terrestrial carbon is stored in soil, which holds almost three times the carbon stored in the atmosphere. When disturbed, soil can release large amounts of carbon dioxide into the atmosphere, which contributes to climate change. While humans are known to contribute to carbon release from soil from different types of land use, scientists know little about the effects of invasive species on soil damage.
For the present study, the researchers used existing models on wild pig numbers and locations to simulate 10,000 maps to estimate their global population density. They then modeled the soil area disturbed by the pigs from a long-term study of wild pig damage across various environmental conditions and climatic conditions. Afterward, they simulated the global carbon emissions from wild pig soil damage using previous research from the Americas, Europe, and China.
In the end, the researchers found that wild pigs are likely uprooting an area of between 36,000 to 124,000 square kilometers in environments in which they are not native. This results in the release of around 4.9 million metric tonnes of carbon dioxide annually, or the equivalent of 1.1 million passenger vehicles.
The researchers point out that more work is needed to assess the variability in wild pig density and soil dynamics before their results can be conclusive. Nevertheless, they say that their research points to an urgent need for more research on the contribution of wild pigs to greenhouse gas emissions that could threaten biodiversity and food security.