Invasive species are one of Australia’s worst environmental problems. Managing them can bring many benefits – including for our climate.
Managing invasive species may help reduce greenhouse gas emissions.
Research from New Zealand estimates nearly 15% of their greenhouse gas emissions could be locked into native ecosystem carbon sinks if they controlled feral browsing animals.
Like New Zealand, Australia’s native ecosystems in their natural state store vast amounts of carbon. But to work as nature intended, they need to be free from invasive weeds and pests.
In Australia, feral animals significantly damage critical carbon sinks like soil, wetlands, peatlands and vegetation through grazing and trampling. This can cause native ecosystems to bleed stored carbon into our atmosphere, contributing to global warming.
Large feral animals like buffalo also burp out the potent greenhouse gas methane. And invasive weeds can fuel hotter, more intense bushfires, releasing huge quantities of emissions in the process.
Invasive species are already one of Australia’s worst environmental problems – causing animal extinction and threatening nature, industries and human health. Their potential impact on climate change provides even more reason to act now.
Here are four areas where eradication, control and management of invasive species in Australia could deliver co-benefits for nature and climate:
Feral pigs erode soil, releasing carbon dioxide
Feral pigs act like ‘mini tractors’, uprooting soil as they search for food, releasing the carbon stored within.
Researchers at the University of Queensland recently looked into the impact of feral pigs on climate change and found they produce as much carbon dioxide as 1.1 million cars every year.
But those emissions aren’t shared equally. Due to our large populations of feral pigs, Australia and New Zealand account for 60% of those emissions. And that’s a conservative estimate – the actual emissions from feral pigs in Australia and New Zealand could be three or four times higher.
Feral horses ravage peatlands, our ancient carbon stores
Peatlands – like the sphagnum bogs of our alpine and sub-alpine regions – are nature’s secret weapon when it comes to tackling climate change. Globally, peatlands store over a third of the planet’s soil carbon. That’s more than in all the world’s forests. Put another way: 5% of the world’s carbon emissions is due to peat moss damage.
In Australia’s alpine regions, feral horses, deer and pigs are ravaging Australia’s precious peatlands, turning them from a safeguard against climate change into a driver of emissions.
What’s worse is peatlands take thousands of years to recover. A study on the impacts of feral horses in the Australian alps shows peat soils build up about 1 metre every 3,000 years. This means vital carbon stores in Australia’s alps damaged by feral horses over just a few decades, will take thousands of years to fully recover.
Invasive weeds like gamba grass can increase the risk and intensity of bushfires, increasing carbon emissions
Gamba grass is a highly invasive weed native to Africa but now established in parts of Australia, including in the Northern Territory. It can grow up to four metres high and fuels hotter, more intense fires – transforming the Top End by reducing tree cover, changing water availability, depleting nutrients and increasing greenhouse gas emissions.
Feral buffalo produce high amounts of methane
More than 160,000 feral buffalo roam the Top End of Australia, causing extensive damage to natural waterholes, destroying wetlands and spreading weeds. These large herbivores also burp out the potent greenhouse gas methane from fermenting vegetation in their stomachs.
Researchers from Charles Darwin University have been evaluating culling feral buffalo for carbon credits. With one adult buffalo emitting the equivalent of more than two tonnes of carbon dioxide per year, that’s a possible two carbon credits per buffalo.
This approach could bring benefits to both landowners and the environment, and help fund invasive species management. The same approach could be applied to other feral animals across Australia, including cattle, camels, goats, and deer.
The Invasive Species Council is commissioning a study like New Zealand’s. We expect that feral deer, camels and other animals are all taking their toll on nature’s natural defence to increasing carbon emissions.