The world is urgently seeking alternatives to fossil fuels - coal, gas, and oil - as energy sources.
Decarbonising our economies is critical if we are to succeed in reducing carbon dioxide emissions, and hence limit global warming and runaway climate change.
One energy source proposed by some industry lobby groups is native forest biomass which can include all or part of a tree's woody trunk and branches. Using forest biomass for energy is now widespread across Europe, and vast quantities of timber are now exported from North America to burn in the United Kingdom, France and elsewhere.
However, data from Europe shows that there has been a major increase in the intensification of logging in Europe over the past five to seven years and this could prevent many European nations reaching their emissions reduction targets under the Paris and Glasgow agreements.
The same process is now being pushed heavily by certain forest industry lobbyists and government agencies in several Australian states, including Tasmania, Victoria and New South Wales.
Lobbyists argue they will only use the by-products from commercial logging operations including the parts of a tree not suitable for timber such as tops, branches and bark, stems arising from thinning operations, and trees cleared for other purposes. But there are a number of reasons why burning forest biomass as a source of energy would be a climate "own goal", making it even harder to achieve net zero emissions.
Biomass burning might be a renewable energy source, but it is not a clean energy source; that's because it still emits CO2. Trees are mostly carbon and burning forest biomass emits CO2 into the atmosphere. Furthermore, the emissions from burning forest biomass are immediate and there is always a significant time lag before an equivalent amount of CO2 is removed from the atmosphere: if the forestry residuals come from a 40 to100 year old tree, it will take 40 to 100 years for an equivalent tree to regrow. Because proposals involve continuously burning forest biomass for energy, there will always be more carbon in the atmosphere than if the forest had remained unlogged.
Proponents of biomass burning also say that all they are doing is cleaning up the debris left on the ground after logging operations. What is left unsaid is that this debris would not be created if native forests were not logged in the first place. Additionally, creating markets for high volume, low value residues from native forests results in significantly more biomass being removed from a given area of logged forest than would otherwise have occurred.
Another problem is that recently published research shows that forests degraded by logging are highly flammable for up to 70 years after cut areas are regenerated. These problems were only too obvious during the catastrophic Black Summer fires of 2019-2020. Of course, more high-severity fires generate yet more carbon emissions.
At the 2021 climate conference, Australia along with 145 other nations, endorsed the Glasgow Leaders' Declaration on Forests and Land Use where they committed to conserve forests, accelerate their restoration and halt and reverse forest loss and land degradation.
The creation of a large-scale commercial bio-energy market based on sourcing native forest biomass will be history repeating. In south-eastern NSW and north-eastern Victoria, in the late 1960s, the export woodchip industry was established to take the so-called residues from logged native forest with the aims of helping to rejuvenate forest structure and converting poor quality stands of trees to extensive regrown forests with high quality sawlogs.
Perversely it became the opposite; market opportunities emerged that shifted forest management from the sawlog production for quality timber products to woodchip production. Hundreds of millions of tonnes of woodchips were exported to Asia and, at times, in excess of 90 per cent of everything cut from the forest was diverted to make woodchips. This did not regenerate a forest with extensive areas of high quality sawlogs. Rather, it reinforced wood chipping operations, with a corresponding marked decline in the sawmilling industry. Today just a handful of small, marginally economic, native forest sawmills now operate across all of south-eastern NSW.
A native forest biomass burning industry will create the same, if not worse, market and resource distortions.
A push to eliminate the use of fossil fuels from economies is critically important. What those fossil fuels are replaced with is equally important. The challenge of decarbonising Australia's energy sector can only be met by using non-carbon renewable energy sources - such as solar PV and wind - that, unlike burning coal and forest biomass, do not generate CO2 emissions.
If fossil fuels are replaced by biomass burning, even at modest levels, there will be perverse impacts, including elevated carbon emissions, reduced forest ecological integrity, increased fire risks, and greater biodiversity loss.
All evidence shows that biomass burning should be excluded from the mix of solutions needed to decarbonise Australia's economy. Biomass burning was included in the Renewable Energy Target by former environment minister Greg Hunt. That was a mistake and he was told so at the time. It is time to remove it under reformed legislation, so that we have a better chance of reaching the 43 per cent emissions reduction target.
- David Lindenmayer is an ecologist and conservation biologist based at the Australian National University; Professor Brendan Mackey and Dr Heather Keith are ecologists based at Griffith University.