Researchers in Australia and New Zealand say wild pigs across the world are having the same impact on the climate as a million cars.
Their research, recently published in Global Change Biology, says by uprooting carbon trapped in soil, wild pigs are releasing about 4.9 million metric tonnes of carbon dioxide per year.
This is equivalent to 1.1 million cars.
The researchers from the University of Queensland and University of Canterbury used models of wild pig population density, soil damage, and their effect on soil carbon emissions to reach their findings.
University of Queensland's Dr Christopher O'Bryan said the wild pigs could be a significant threat to the climate.
"Wild pigs are just like tractors ploughing through fields, turning over soil to find food," O’Bryan said.
"When soils are disturbed from humans ploughing a field or, in this case, from wild animals uprooting, carbon is released into the atmosphere.
"Since soil contains nearly three times as much carbon than in the atmosphere, even a small fraction of carbon emitted from soil has the potential to accelerate climate change."
"Our models show a wide range of outcomes, but they indicate that wild pigs are most likely currently uprooting an area of around 36,000 to 124,000 square kilometres, in environments where they’re not native," he said.
"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."
University of Canterbury PhD candidate Nicholas Patton said the research has ramifications for curbing the effects of climate change.
"Invasive species are a human caused problem, so we need to acknowledge and take responsibility for their environmental and ecological implications," Patton said.
"If invasive pigs are allowed to expand into areas with abundant soil carbon, there may be an even greater risk of greenhouse gas emissions in the future.
"Because wild pigs are prolific and cause widespread damage, they’re both costly and challenging to manage."
"Wild pig control will definitely require cooperation and collaboration across multiple jurisdictions, and our work is but one piece of the puzzle, helping managers better understand their impacts," he said.
"It’s clear that more work still needs to be done, but in the interim, we should continue to protect and monitor ecosystems and their soil which are susceptible to invasive species via loss of carbon."