The National Observer
What runs through your mind when you’re deciding which toilet paper to buy? Sale price, roll size, pitiful single-ply or luxurious triple? Climate change might not make your list of considerations, but it should. Story here.
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Nature
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| Bushfire East of Lake Dundas, Western Australia. Photo by Pierre Markuse |
The 2019–2020 Australian wildfires released more than twice as much CO2 as previously reported on the basis of different fire inventories, reports a Nature paper.
An independent study also published in Nature, suggests that aerosol emissions from these wildfires are likely to have fuelled vast plankton blooms thousands of kilometres away in the Southern Ocean.
The findings highlight the complex links between wildfires, ecosystems and the climate. Climate-change-driven droughts and warming play a role in increasing the frequency and intensity of wildfires, which release CO2 into the atmosphere, potentially driving further climate change and increasing the risk of wildfires.
In the summer season of 2019–2020, around 74,000 km2 — an area roughly equivalent to 2.5 times the area of Belgium — burned in the eucalyptus forests in the coastal regions of Victoria and New South Wales, Australia. These wildfires are known to have been extremely large in scale and intensity, and to have released large amounts of CO2 into the atmosphere, but emission estimates remain uncertain.
To gain insights into the amount of CO2 released by the Australia wildfires, Ivar Van der Velde and colleagues analysed new high-resolution satellite measurements of carbon monoxide concentration in the atmosphere, from which they infer fire-induced carbon emissions. They estimated that around 715 teragrams of CO2 were emitted between November 2019 and January 2020 — more than twice the amount previously estimated from five different fire inventories and comparable to a bottom-up bootstrap analysis of this fire episode, surpassing Australia’s normal annual fire and fossil fuel emissions by 80%.
Gaining a stronger understanding of the atmospheric burden of CO2 caused by these fires, and what they will cause in the future, is critical for constructing future scenarios of the global carbon balance, the authors note.
In addition to carbon emissions, wildfires release aerosols that affect ecosystems; for example, transportation of nutrients such as nitrogen and iron can enhance plankton growth. Nicolas Cassar, Weiyi Tang and colleagues report the presence of extensive phytoplankton blooms from December 2019 to March 2020 in the Southern Ocean, downwind of the fires. Aerosol samples originating from the fires contained high levels of iron, which the authors suggest were transported vast distances and fertilized the blooms.
Together, these studies demonstrate that wildfires can have an important influence on atmospheric CO2 levels and ocean ecosystems.
Nature
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The Amazon - Manaus, Brazil. Photo by Bruno Kelly
The Amazon Basin has a vital role in regulating the Earth’s climate and is home to 10% of all known species. Degradation of the forest threatens the resilience of this ecosystem; around 21–40% of the forest cover is predicted to be lost by 2050, which will have large impacts on Amazonian biodiversity.
To better understand these impacts, Xiao Feng and colleagues investigate how forest fires have been affecting the geographic range of 11,514 plant species and 3,079 animal species over the past two decades.Up to 85% of species listed as threatened in the Amazon may have lost a substantial portion of their habitat owing to deforestation and fires in the past two decades, a study in Nature indicates. It is estimated that for every 10,000 km2 of forest that is burned, about 27–37 additional plant species and about 2 or 3 more vertebrate species that have more than 10% of their range in the Amazon will be affected. As fires move closer to the heart of the Amazon Basin, which has greater levels of biodiversity, the impact of fires on biodiversity is expected to increase.
Since 2001, up to 189,755 km2 of Amazon rainforest have experienced fires - as much as four % of the total area. This has impacted the ranges of as many as 85 % of species listed as threatened in this region. They note that periods of increased fires correlate with relaxation of policies designed to slow deforestation and forest burning.
In Brazil, policies to reduce deforestation implemented in the mid-2000s were relaxed in 2019, which saw an increase of up to 28% in fire-impacted area, affecting the ranges of an estimated 12,064–12,801 plant and vertebrate species.
These findings demonstrate the connection between policy and forest fires and how these factors can impact biodiversity, the authors conclude.
