Agriculture and forestry: hidden emissions, solution in plain sight

Agriculture and forestry activities cover most of Australia, but increasingly, no longer our national consciousness. With most of our population now living in the cities, the remainder of the continent is often forgotten. The vast space between our coastlines is not empty, however. In fact most of it is farmed and managed for a wide variety of commercial purposes.

Beyond Zero Emissions has been working for several years on a major research project to look at reducing greenhouse emissions from the Land Use sector — agriculture and forestry. The result, released this week, is the Zero Carbon Australia Land Use Report.

The report shows a surprisingly high emissions profile for the Land Use sector, a sector that will be most impacted by climate change. But well-understood and already widely practiced strategies can move the sector a long distance towards the goal of zero emissions, helping to prevent the worst impacts of climate change.

The research proceeded from an initial investigation into where emissions in the sector come from, and at what magnitude. It turns out that various activities on the land including farming, forestry, and land-clearing, account for a huge proportion of our national emissions. This is masked in our national accounts, which splits the sector and offsets its emissions against reductions from revegetation of land.

By including all emissions from farming and land-clearing for agriculture, we derived a figure of 33 per cent of Australia’s annual emissions coming from land use practices.

The largest contributor was land clearing and re-clearing, followed by enteric fermentation (the production of methane by ruminant animals’ digestive systems, mainly cattle and sheep).

The report also found that carbon stocks in native forests are systematically underestimated by a factor of up to four or five, so that the climate impact of native forest logging is much higher than previously thought. If the report had been able to include an adequate appraisal of emissions from clearfell logging, total land use emissions would be higher still.

The second surprising finding of the study comes from an analysis of the short-lived greenhouse gases emitted from land use. Some of these are not typically included in the international reporting of emissions. As well as hundred-year global warming potential (GWP), the report looked at the twenty-year GWP of all these different emissions. For example, whereas the warming impact of methane is only 24 times that of carbon dioxide using one hundred-year GWP, over twenty years, the warming impact is at least 84 times.

As a result of examining these short-lived gases, over a time-scale more relevant to their effect on global warming, we find that at twenty-year GWP, Australia’s land use emissions may be closer to 54% of total national emissions.

With these new perspectives, the Land Use sector is right up there with the highest emitting sectors of Australia’s economy. But the report also shows that there is massive scope to reduce emissions of short-lived greenhouse gases, giving a relatively fast, sharp reduction to Australia’s global warming impact.

Emissions abatement is possible by making changes to land management practices such as savannah burning, clearfell logging and land clearing for agriculture. Technologies and management techniques, including those for enteric fermentation reduction, can also bring down emissions, and a good many of these are reviewed and explained in the report.

The report highlights a path to reduce Australia’s agriculture emissions from almost 190Mt/yr to around net zero, with reductions of 58 Mt/year from land clearing, 23 Mt/yr from re-clearing, 9 Mt/yr from savannah burning, 37Mt from enteric fermentation, 4 Mt/yr from soil carbon and 2 Mt/yr from manure management. Carbon sequestration of 45Mt/yr is achieved from limited revegetation.

We also need to find ways to put trees back into the countryside on a scale large enough to negate land-based emissions in each biogeographic region of Australia. Our researchers looked at 300 sub-regions in Australia to calculate what this would look like. Revegetating on this scale is something many farmers have already made a start on. Environmentalists have also been campaigning for this for many years. Farmers and communities on the land should have the support to operate on the front line of Australia’s efforts to combat climate change; they are certainly the people most affected.

Regional centres will benefit from implementing changes to land use in a way that reduces carbon pollution. New revenue streams could open up to farmers, allowing them to remain on their properties; bringing young people back to rural Australia. Regional areas could be rejuvenated by new jobs, more people, and more income – a stark contrast to the situation we face where farmers are being forced to leave their land from drought and increasing number of extreme weather events.

These measures are not something that we would see as offsets to compensate for emissions in other sectors of the economy. They are calculated in the study at a level to negate the emissions from agricultural practices (and forestry) in the region where they occur. While the report shares many common areas with current discussion of concepts like soil carbon, this is a key difference.

Of course, measures like revegetation do not just benefit our climate. Partial revegetation of farmland has, in many areas, been shown to have benefits not just for the local environment, but for farming operations as well. Many farmers are already interested in undertaking measures identified in this report, if they could afford the time and expense to do it. So the report analyses at a high level what it might cost to support farmers to make the necessary changes.

Can we do it? If avoiding dangerous climate change isn’t enough incentive, returning forest and woodlands to the landscape, revitalising rural areas, diversifying income streams for farmers and improving the productivity and sustainability of our farms are good reasons too.