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Feral hogs have outsized climate impact 'greater than a million cars'

There are way more than 30 to 50 feral hogs out there ripping up soil.

- 01:58

Wild pigs are uprooting large areas of soil and releasing carbon.

The University of Queensland

The US Department of Agriculture calls feral swine "a dangerous, destructive, invasive species." Wild pigs -- the escaped or released descendants of farm animals -- may also be making a worrying contribution to our global climate crisis.

A study led by researchers from the University of Queensland in Australia and the University of Canterbury in New Zealand found that wild pigs around the world are uprooting massive areas of soil. This results in the release of "around 4.9 million metric tonnes of carbon dioxide annually across the globe, the equivalent of 1.1 million cars," said the University of Queensland in a statement on Monday. 

The university's Christopher O'Bryan likened the pigs to tractors plowing fields. The hogs' activity releases carbon dioxide, a greenhouse gas that contributes to global warming. "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," said O'Bryan.

The USDA estimates that there are over 6 million feral swine in the US alone, with the population growing rapidly. There are up to 24 million feral pigs in Australia. Population control measures include hunting, trapping and poisoning.

The researchers simulated thousands of maps of potential global wild pig density and crunched the numbers on the soil disturbance they cause. Any way they looked at it, the animals were impacting huge areas of land in places where they're not native. The study is published in the journal Global Change Biology.

Rising carbon dioxide levels in the atmosphere have been linked to human activities. Said study co-author Nicholas Patton of the University of Canterbury, "Invasive species are a human-caused problem, so we need to acknowledge and take responsibility for their environmental and ecological implications."  

Wild pigs made news in 2019 when destructive Canadian hogs were spotted pressing in on the US border, and also when "30-50 feral hogs" became a meme after musician Jason Isbell got into a Twitter conversation about gun control.

The meme was pretty funny, but the reality of the impact of feral pigs is not.