Australia’s natural environment is pretty special, but it’s no magic pudding. [26 August 2013 | Peter Boyer]
Storing more carbon in farm soils isn’t the panacea that some are claiming. ABC PHOTO
You probably know Albert, the magic pudding that never gets smaller no matter how many slices are cut from it. Nearly 100 years old, Norman Lindsay’s funny, feisty children’s tale remains an Australian favourite.
The pudding is a very desirable possession because it can feed any social gathering, but those who claim to own it take it for granted, leaving it out of their conversations and generally treating it shabbily. It responds by making life difficult for those who covet it.
Lindsay’s pudding has inspired countless metaphors. Last week Prof Richard Kingsford, director of the University of NSW centre for wetlands, rivers and landscapes, gave us another: the way we treat the natural environment as a limitless source of wealth.
We see this “magic pudding”, he said, as a place where “you can easily establish new agriculture, develop more rivers, clear more land, dig another mine or establish a new fishery, in the vain hope that once a resource is depleted, another will magically be found”.
Here’s another item for that list: solving our little problem with carbon emissions. Having mined nature for coal, oil and gas, we expect this same magic pudding to clean up our act for us so that we can continue using our wonder fuels with gay abandon.
We know that plants take in carbon from the air and store it till they die, and that undisturbed soil can retain carbon indefinitely. Hence the argument, which I and many others have espoused, that conserving forests and reducing ploughing will help bring carbon dioxide down to safe levels.
This has brought welcome bipartisan support for research into how plants and soil can take up excess carbon dioxide. But while helping to improve abatement techniques, the research has also reminded us that nature does things in its own time and there isn’t a lot we can do to speed this up.
Australia’s land carbon fluctuates enormously with climate. In dry years the land releases vast amounts of carbon from drying soil and decaying plants, and takes it back again with growth in wet years. These swings are larger than the entire accounted Australian greenhouse gas balance.
So land carbon mitigation is investment in a very volatile carbon bank, and tracking its intricacies and underlying trends is a huge challenge. CSIRO land carbon specialist Michael Battaglia believes it will be many years yet before we can say we’ve mastered this task.
Land abatement policies need data from real life — not just the total hectares that can be dedicated to conservation tillage or physically planted with trees, but also constraints with water, logistics and equipment, competing land use options, farmers’ preferences and investment risks.
The bottom line is that while we can greatly improve our land abatement capacity to many megatonnes of greenhouse gas a year, it’s a process that will take decades, because we must change land management practices and develop new technologies. And we must get the quantities right.
Battaglia estimates that while we might reduce as much as 20 per cent of our current emissions through land measures by 2050, the steady build-up of fossil carbon in the air over that time will substantially reduce that figure.
He calculates that changing cropping and pastoral practices to improve soil carbon will be a relatively small part of land abatement, especially in the years to 2020. More significant — though still limited — will be reforestation and avoided land clearing.
His assessment is contested by an active soil carbon lobby, which points to better farming practices arising out of recent field trials that promise much greater carbon take-up and storage in soils. This is to be applauded and supported, but it will meet only a fraction of our carbon abatement needs.
If it wasn’t for humans, fossil carbon would remain underground forever. Its level in the atmosphere is rising by 3 per cent a year and it now accounts for about 90 per cent of the rise in greenhouse gases. Australian mitigation will go nowhere unless we do something about our fossil fuel use.
We need our emissions to be heading strongly down by 2020. Australia’s bipartisan target for 2020 is to have its emissions just 5 per cent below what they were in 2000. We’re battling to get there, but in any case it doesn’t come close to meeting the real need.
Emission targets allow too much wriggle room. Instead, carbon accounting specialists argue for adoption of a global carbon budget — the amount of carbon the world can burn without going over the agreed 2C “safe” limit — and a carbon quota for each country based on its population.
We know how much carbon dioxide Earth’s atmosphere can hold before climate is destabilised. We have to ensure the carbon we emit when we burn coil, oil and gas doesn’t push us over this limit, and the longer we delay reducing our emissions the harder it gets later on.
Fossil fuel reserves are estimated to hold 3000 billion tonnes of carbon, rising with each new discovery. To avoid unstoppable warming we must leave over 80 per cent of it undisturbed. Going by the world’s present emission trajectory, that’s simply beyond us.
To take at face value what’s been said so far in this election campaign, we can deduce that reaching our 2020 target will be a real achievement, that a smaller financial penalty for carbon pollution is a good thing, and that carbon sequestered by trees and soils will substantially reduce our emissions.
None of this is true. The debate about climate in this election campaign is founded substantially on false or misleading assumptions. Until it begins to reflect reality we’re just messing about, re-arranging deck chairs on a foundering ship of state.
• At 6.30 pm next Monday, the acclaimed documentary Chasing Ice, featuring dramatic time-lapse images of a warming planet, will screen at the Dechaineux Theatre, School of Art, Hunter Street, Hobart. Prof Matt King of the University of Tasmania will host a Q&A after the screening.