The IPCC’s new report, approved overnight, calls for all nations to transform the way land is managed because agriculture, forestry and other land use produces almost a quarter of greenhouse gas emissions.
Dermot O’Gorman, CEO of the World Wide Fund for Nature-Australia, says there is immense opportunity in Australia to work with agriculture to limit the worst impacts of climate change.
“There is tremendous potential for vegetation and soil to suck up and store greenhouse gases to help achieve a 1.5-degree future,” Mr O’Gorman said.
“Right now too much of Australia’s soil is degraded or being eroded away. Too many forests have been lost and remaining trees continue to be cut down.
“Australia can turn this around by protecting our remaining forests, transforming marginal grazing or cropping land into profitable carbon farms by returning trees, and adopting innovative farming techniques.
“Scientists say these steps are necessary to reduce emissions and avoid the worse impacts of global warming,” Mr O’Gorman said.
Australia has lost nearly 50% of our forests
Forests trap carbon in soil and vegetation thus lowering greenhouse gas emissions.
The federal government’s 2016 State of the Environment Report says “about 30% of Australia’s land area was covered in forest before European colonisation; today, only about 16% of the land area is forest”.
That means we’ve lost nearly 50% of our forests. That clearing has released billions of tonnes of carbon.
Clearing continues, so much so that WWF’s Living Forests Report includes Australia as the only developed country on the list of 11 global deforestation fronts.
The National Greenhouse Gas Inventory estimates deforestation in Australia released 1.8 billion tonnes of carbon from 1990 to 2017.
Trees make rain
Two prominent scientific papers found that the destruction of trees was impacting rainfall in Australia. One concluded that clearing for agriculture in Australia “is likely to have contributed to a hotter and drier climate and exacerbated the effect of the El Nino by increasing the severity of droughts, especially in south-east Australia”.
The other study said: “the clearing of native vegetation is having a significant effect on climate extremes including the duration and severity of droughts in eastern Australia”.
We’re losing our soils
Clearing has contributed to serious erosion problems from water and wind. It’s estimated hillslope erosion currently moves 4.8 billion tonnes of soil per year in Australia, compared to 2.9 billion tonnes per year before European settlement.
In much of Australia, soil is washed away faster than it can be formed and in some agricultural areas half the soil will be eroded away in decades.
Scientists say 75% of dust in Australia is caused by human activities including land clearing for crops and pasture, and overgrazing by livestock.
The CSIRO says the 2009 dust storm known as Red Dawn removed 2.5 million tonnes of soil and directly cost the NSW economy around $300 million.
Our farms suffer
In Australia, about two thirds of agricultural land is degraded by soil erosion, soil salinity, soil acidity, soil contamination, nutrient loss and soil structure decline.
Clearing native vegetation for agriculture can significantly decrease the organic carbon in soil by up to 70%.
Trees boost soil carbon, enhance soil resilience, sustainability and productivity and soak up greenhouse emissions.
Fertiliser use has risen dramatically
Nitrogen fertiliser use in Australia has risen from 440,000 tonnes in 1990 to 1.5 million tonnes in 2017.
That has contributed to more nitrous oxide emissions from agriculture which have risen from 41 thousand tonnes in 1990 to 51.6 thousand tonnes in 2017 … a 25% increase.
As a greenhouse gas, nitrous oxide is 300 times worse than carbon dioxide, and has an atmospheric lifetime of 110 years.
It doesn’t have to be this way
Australia’s remaining forests cover 132 million hectares and are the seventh largest reported forest area of any country worldwide.
Our surviving forests store about 22 million tonnes of carbon, and are a globally significant carbon sink that must be managed so as not to become a source.
Innovative farming techniques, including regenerative grazing, are part of the solution. When herds are kept together and graze paddocks at higher density for shorter periods, grass cover improves, soil carbon increases, soil health recovers, and erosion is reduced.
The CSIRO’s Australian National Outlook 2019 imagines a future in which about half of the nation’s marginal, intensely farmed land is transformed into profitable forests.
These forests would trap carbon to be sold as a carbon credit.
By 2060, up to 30 million hectares could be profitably transitioned to carbon plantings.
This could offset as much as 700 millions of tonnes of CO₂ equivalent, allowing Australia to become a net exporter of carbon credits and earning landowners as much as $114 billion per annum.
Much of these carbon plantings would be native species, helping to restore the ecosystem health upon which Australia’s agricultural productivity and biodiversity depend.