Savannah burning under the Australian carbon credit scheme harms human health
Savannah burning projects in Northern Australia provide economic benefits to indigenous communities and claim that Reduce emission of greenhouse gasses. But our research suggests that smoke from these projects harms human health.
The Savannahs of Northern Australia about 25% of the landmass of Australia. They are among the most flammable regions in the world, making up 70% of Australia’s fire-affected area annually.
Savanna fire management involves strategically burning grasslands early in the dry season, ostensibly to reduce the likelihood of large, intense, more carbon-intensive fires later in the season. Under the Australian Emissions Reduction Fund, land managers who burn savanna receive financial rewards in the form of carbon credits.
The Top End’s Smoking Problem
Savanna fire management is currently a topic of significant global interest, much of which stems from its potential to reduce carbon emissions.
The underlying premise is that combustion in the early dry season releases fewer emissions than combustion in the late dry season. This is because the fuel is moister and the weather conditions are milder, so the fires will be smaller, less fuel will ignite and less carbon will be released.
In Australia, in the mid-2000s, savanna carbon reduction programs were developed and integrated into the carbon market. Land managers get financial incentives to burn large amounts of savanna before the end of this year July every year.
Australia now touts itself as a world leader burn in savanna. We share the practice with other regions around the world and savanna burning programs linked to carbon markets have been proposed elsewhere.
Yet the effects of smoke pollution from such programs are rarely taken into account. In Australia’s Top End, for example, the communities cover thick and long-lasting smoke blankets every dry season. Darwin, a city of 158,000 people, regularly exceeds the Australian air quality standard for particulate matter.
In Darwin, smoky days cause more hospital admissions lung and heart diseaseand more presentations in the emergency department for asthma. these effects disproportionate affect the indigenous population.
Nearly all of Darwin’s particulate pollution is caused by landscape fires. In the early dry season, almost all of this is generated by prescribed combustion – and in recent years there has been a marked increase in combustion associated with carbon reduction schemes.
What our research found
Our study looked at the relationship between prescribed combustion and smoke pollution in Darwin from 2004 to 2019.
We first assessed the very small particles in smoke, known as PM2.5. We then analyzed fire activity within a 500 km radius and assessed the links between pollution, weather and fire.
The results showed Air quality deteriorated in Darwin in the early dry season (particularly in June and July), with an increase in the annual number of severely polluted days.
Perhaps surprisingly, air quality did not change significantly in other seasons. In other words, shifting savanna burning to the early dry season did not seem to lead to better air quality later in the season.
Our findings reveal a complex story. Despite a substantial expansion of savanna burning for carbon reduction during our study period, Darwin net annual PM2.5 concentrations did not decrease. In fact, there was an increase in the number of violations of the national air quality standard.
So what drives these results? An important factor is that large savanna areas southeast of Darwin were burned in the early dry season for carbon reduction. At that time of year, Darwin encounters a steady southeast trade wind, carrying much of the smoke from these fires.
Fuel dynamics can also play a role. Native and non-native grasses that are highly flammable in the early dry season to expand on often burned savannas. Higher temperatures can cause fuel to dry out earlier in the dry season. These factors can cause fires in the early dry season to be as extensive and intense as savannas burned later in the season.
Our research comes with caveats. For example, we have only drawn broad conclusions about the geographic sources of smoke over Darwin. Nevertheless, our results clearly show that Darwin’s already significant air quality problem is exacerbating rather than improving, coupled with increased combustion in the early dry season.
A balancing act
All this does not mean that the burning of savanna has to stop, nor that traditional owners should not be paid to manage the fire on the land. But it does mean that policies should be designed to minimize unintended harm and maximize benefits.
Policy makers need to think about how to regulate combustion to avoid exposure to smoke pollution. In Darwin, particular attention may be required at locations southeast of the city. One solution may be to regulate how much smoke can be released in a particular room on a given day.
The new Labor government has commissioned an independent assessment of the fund. To fulfill this review it’s shortaccount must be taken of any accidental damage.
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Quote: ‘Unacceptable Cost’: Savannah Burning Under Australia’s Carbon Credit Scheme Harms Human Health (2022, Aug 10) retrieved Aug 10, 2022 from https://phys.org/news/2022-08-unacceptable-savanna-australia-carbon-credit .html
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