Untouched eucalypt forests store three times more carbon than official UN climate change figures suggest, according to a study by the Australian National University.
The study by ANU researchers revealed that the eucalypt forests of south-eastern Australia store 25.5 billion tonnes of carbon, or 640 tonnes per hectare on average. The UN Intergovernmental Panel on Climate Change (IPCC) assigns a carbon storage value, used in the Kyoto Protocol, of just 217 tonnes per hectare for the same forests.
The discrepancy appears to have a lot to do with the UN methodology which assigns a general carbon storage volume to all forests, including old-growth stands and plantations. Yet the study, "Green Carbon, the role of natural forests in carbon storage", found enormous differences between carbon storage between older and younger trees.
Using data collected on the ground and from satellite imaging of 240 sites over 14.5 million hectares, the scientists found that the more untouched a forest, the greater its carbon store in the total biomass of the trees and soil. It found that the oldest areas of forest with trees up to 80 metres tall can store 2000 tonnes of carbon per hectare.
The IPCC carbon calculations are based on plantation forests and include trees down to two metres in height.
Brendan Mackey, an environmental science professor at ANU and lead author of the study, said the study’s findings increase the value of forests in fighting climate change. Whilst the study is specific to eucalypts in Australia, the results are likely to have implications for carbon storage estimates in forests around the world, especially those in temperate zones.
"In Australia, and probably globally, the carbon-carrying capacity of natural forests is underestimated and therefore misrepresented in economic valuations and in policy options," the study concludes.
The Australian Conservation Foundation said the new figures show Australia could cut its greenhouse gas emissions by around 24 per cent by halting logging of the country’s native forests. This means for Australia at least, it is “one of the quickest, largest and cheapest ways” to reduce greenhouse emissions,” said ACF’s climate change manager Tony Mohr.
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Green Carbon, the role of natural forests in carbon storage