How wildfires trap carbon for centuries to millennia
2019 AUG 20 (NewsRx) -- By a
The extensive and unprecedented outbreak of wildfires in the arctic and the vast amounts of CO2 they are emitting have been hitting the headlines across the world.
But a new Nature Geoscience study quantifies the important role that charcoal plays in helping to compensate for carbon emissions from fires. And the research team say that this charcoal could effectively ‘lock away’ a considerable amount of carbon for years to come.
In an average year, wildfires around the world burn an area equivalent to the size of
As vegetation in burned areas regrows, it draws CO2 back out of the atmosphere through photosynthesis. This is part of the normal fire-recovery cycle, which can take less than a year in grasslands or decades in fire-adapted forests.
In extreme cases, such as arctic or tropical peatlands, full recovery may not occur for centuries.
This recovery of vegetation is important because carbon that is not re-captured stays in the atmosphere and contributes to climate change.
Deforestation fires are a particularly important contributor to climate change as these result in a long-term loss of carbon to the atmosphere.
Now, a new study by researchers at
Lead author Dr
“However, in a fire some of the vegetation is not consumed by burning, but instead transformed to charcoal. This carbon-rich material can be stored in soils and oceans over very long time periods.
“We have combined field studies, satellite data, and modelling to better quantify the amount of carbon that is placed into storage by fires at the global scale.”
The paper, which was co-authored by Dr
The researchers say this pyrogenic carbon needs to be considered in global fire emission models.
“Climate warming is expected to increase the prevalence of wildfires in many regions, particularly in forests. This may lead to an overall increase in atmospheric CO2 emissions from wildfires, but also an increase in pyrogenic carbon storage. If vegetation is allowed to recover naturally then the emitted CO2 will be recaptured by regrowth in future decades, leaving behind an additional stock of pyrogenic carbon in soils, lakes and oceans.
“We expect any additional pyrogenic carbon to be trapped for a period of centuries to millennia, and although it will eventually return to the atmosphere as charcoal degrades, it is locked away and unable to affect our climate in the meantime.
“This brings some good news, although rising CO2 emissions caused by human activity, including deforestation and some peatland fires, continue to pose a serious threat to global climate.”
There are still important questions to be answered about how a warmer, more drought-prone climate will affect the global extent of wildfires in the future. For example, will there be more fire in arctic peatlands as we are experiencing this summer, and what proportion of CO2 emissions will be recaptured by future vegetation regrowth?
But this new research shows that pyrogenic carbon production should be considered as a significant product of fires and an important element of the global carbon cycle. Global fire emissions buffered by the production of pyrogenic carbon is published in the journal Nature Geoscience.
(Our reports deliver fact-based news of research and discoveries from around the world.)
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