It’s also one of the world’s more significant contributors to climate change and, of the so-called ‘developed’ nations, one of the most reticent to abandon its attachment to the fossil-fuel sector.
In Australia, carbon drawdown has additional benefits.
Agriculture is at once part of the problem and a key to the solution.
Farming requires clearing land, reducing biodiversity, running machinery and, often, raising livestock that burp methane, another potent and aggressive greenhouse gas.
But there are ways that agriculture can help remove CO2 from the atmosphere and sequester it, permanently or semi-permanently, in plant matter and soils.
Australian farmers can be paid in exchange for carbon credits for planting trees in their field margins, or for revegetating previously barren land.
But these schemes are optional and, for the moment says O’Brien, the carbon price isn’t high enough to produce a strong incentive for more landowners to engage.
“Trees grow quickly at first, and then they slow down and reach a maximum point where you don’t get a lot of additional annual carbon,” explains Brett Bryan, Alfred Deakin Professor of Global Change, Environment and Society at Deakin University.
“The land will burn from time to time, but most times it won’t be a complete burn and the trees will bounce back,” says Bryan.
In 2015, while working at CSIRO, Bryan co-authored a report about the potential for carbon sequestration in Australia.
Instead, Bryan says that Australian farmers, many of whom have struggled through successive years of drought and flooding, have to consider the trade-offs.
“Something we need to understand here is that there’s not only co-benefits in terms of biodiversity, there can be trade-offs,” he explains.
Then, there’s the somewhat vague concept of ‘soil carbon’.
“Soil carbon is not one thing, it’s probably hundreds of things,” he explains.
“The other lightweight type of soil carbon that people like to cheat and count is called particulate organic matter ,” he says.
The first type is called mineral associated organic matter – fine particles within the soil that have been there possibly for thousands or tens of thousands of years, attached to minerals.
“We’re actively looking at processes to build mineral associated organic matter, increasing aggregate formation.
“The truth is today, it’s the Wild West.
So, the science of soil carbon is still being drawn out through research.
To make biochar, you burn organic matter in an oxygen-free environment to produce a type of charcoal that’s rich in carbon and can endure in soil for thousands of years.
Another, similar method is known as bioenergy with carbon capture and storage .