Wild Pigs Release More Carbon Dioxide Than Million Cars as Invasive Species Uproot Soils Everywhere

Using advanced mapping techniques and predictive population models, a new study demonstrates how burrowing wild pigs actually release more carbon dioxide into the atmosphere than a million cars each year.

The new project, led by researchers from the University of Canterbury and the University of Queensland, found out that pigs release carbon dioxide trapped in the earth. The equivalent release is pegged at 4.9 million metric tons of greenhouse gas, or the equivalent emission of about 1.1 million cars.

Details of the inquiry appear in the latest Global Change Biology journal, in the primary research article titled "Unrecognized threat to global soil carbon by a widespread invasive species."

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An Unseen Contributor to Global Warming

The point of the study, according to researchers, is to better understand the global carbon footprint from invasive species, which, in this case, are the wild pigs — an effect noted by the Australian Government. There is already a significant body of study that addresses and monitors the effect of various anthropogenic activities — modern land-use practices chief among them — on releasing carbon dioxide into the atmosphere. Researchers also point out that the continuous growth of the wild pigs' population and expanding into other ecosystems as invasive species could be a significant threat that would accelerate global warming.

"Wild pigs are just like tractors plowing through fields, turning over soil to find food," says Dr. Christopher O'Bryan, an author of the study from the University of Queensland, in a university news release. He adds that carbon dioxide trapped in the soil is uprooted when disturbed, for example, when humans plow fields. In this case, wild animals like wild pigs uproot the soil and disturb them, causing a similar effect. O'Bryan additionally notes that since soil contains up to three times more carbon dioxide than those present in the atmosphere, even the slightest release from disturbing soil could speed up climate change.

He explains that in the new study, they generated various models to show different outcomes, but their mapping shows that wild pigs might be uprooting a land area anywhere from 36,000 to 124,000 square kilometers. What is worse is that most of the lands where these mappings were taken are environments where wild pigs are not native species.

"This is an enormous amount of land, and this not only affects soil health and carbon emissions, but it also threatens biodiversity and food security that are crucial for sustainable development," O'Bryan added.

Tracking How Pigs Speed Up Global Warming

Using available data on the population and location of wild pigs, the research team simulated 10,000 maps that describe the population densities of wild pigs around the world. Then, they created a model for the amount of soil area disturbed, using a long-term study of wild pigs and the damage they created across different environments, vegetation types, and elevations that ranged from lowland grasslands to sub-alpine woodland areas.

The next step was to characterize the global carbon emissions from the two previously generated models, looking at their impact in the Americas, Europe, and China.

While it was wild pigs this time, University of Canterbury Ph.D. candidate Nicholas Patton clarified that the spread of invasive species is still rooted in human activities. So acknowledgment and responsibility are necessary to start addressing this aspect of continuous global warming.