The devastating Australian fires released twice as much C02 as warming the climate than previously thought, but they also caused huge flowering algae thousands of miles away that may have absorbed significant extra carbon, according to studies released Wednesday.
Severe summer heat and drought helped cause fires from late 2019 to early 2020 that killed 33 people and tens of millions of wildlife, while destroying large expanses of eucalyptus forest.
These “black summer” fires, which surrounded Sydney and other cities of smoke and ash for months, were known to have released large amounts of carbon dioxide into the atmosphere, but the exact amount was difficult to quantify.
To find out, researchers in the Netherlands used a new satellite technology that allows them to monitor the gases released during a fire on a daily basis.
They produced estimates of global emissions as well as released carbon dioxide, concluding that the amount was estimated to more than double previously from five different fire inventories.
“We found that the CO2 emissions from this event were significantly higher than those normally emitted by all Australians with the burning of fossil fuels in a whole year,” said Ivar van der Velde of the Dutch Space Research Institute. SRON, lead author of the article published in the journal Nature.
While still uncertain, he said “given current global warming trends, we believe it is very possible that we will see more of this type of large forest fires in Australia and possibly elsewhere.
“This will likely help get even more CO2 into the atmosphere than expected.”
Forest fires are consistent with a warmer world, as climate change makes droughts and heat waves more frequent and intense.
Depending on how much CO2 is removed from the plants as they grow, emissions can help increase warming.
– “Fertilize the ocean” –
The fires also released aerosols carrying nitrogen and iron particles that can cause oceanic “blooms” of microscopic algae, called phytoplankton.
In a separate study in Nature, researchers found that high levels of iron pumped into the air by fires caused enormous distances, eventually causing a significant increase in phytoplankton in the Pacific Ocean thousands of miles from Australia.
Previous studies have suggested that wildfires could sow algae flowering, said co-author Joan Llort of the University of Tasmania’s Institute for Marine and Antarctic Studies.
But he said the “most striking was the magnitude” revealed in the investigation, with flowers covering a larger area than Australia itself.
Phytoplankton plays a crucial role in the global climate as it takes in CO2 while doing photosynthesis in a process similar to plants.
Some of this carbon eventually sinks into the deep ocean and is stored.
“Our results provide evidence that iron from forest fires can fertilize the ocean, which can lead to a significant increase in carbon uptake by phytoplankton,” said co-author Nicolas Cassar of the Nicholas School of the Environment. Duke University.
But he said finding out whether the amount by which the fire emissions could be offset by the C02 absorbed by the microalgae flowers planted by the fires is the “Holy Grail” of the investigation and is still uncertain.
klm / nrh / lc