Forest fire Black carbon as a positive climate feedback
Tom Goreau
- NB Black carbon can make up to half the carbon in soil, especially wherever forests were burned down to create agricultural or pasture land, and it decomposes at extremely low, practically negligible rates.
- Fire derived forms of carbon are present in most soils as unweathered charcoal and weathered black carbon.[10][11] Soil organic carbon is typically 5–50% derived from char,[12] with levels above 50% encountered in mollisol, chernozem, and terra preta soils.[13]
In addition the black carbon sitting on top of glaciers and Arctic Ice caps is greatly increasing ice melting, you can see that clearly in today’s BBC piece: Alps glaciers melting faster as heatwaves hit
Video content
Video caption: Global warming: Alps glaciers melting faster as heatwaves hit
Global warming: Alps glaciers melting faster as heatwaves hit
Video shows meltwater flowing as data suggests glaciers may lose the most ice in at least six decades.
- Review Article
The black carbon cycle and its role in the Earth system
- Alysha I. Coppola,
- Sasha Wagner,
- Sinikka T. Lennartz,
- Michael Seidel,
- Ward Nicholas D.,
- Thorsten Dittmar,
- Cristina Santín &
- Matthew W. Jones
Nature Reviews Earth & Environment volume 3, pages516–532 (2022)Cite this article
Abstract
Black carbon (BC) is produced by incomplete combustion of biomass by wildfires and burning of fossil fuels. BC is environmentally persistent over centuries to millennia, sequestering carbon in marine and terrestrial environments. However, its production, storage and dynamics, and therefore its role in the broader carbon cycling during global change, are poorly understood. In this Review, we discuss BC cycling across the land-to-ocean continuum. Wildfires are the main source of BC, producing 128 ± 84 teragrams per year. Negative climate–BC feedbacks could arise as wildfire increases with anthropogenic warming, producing more BC, which in turn will sequester carbon, but the magnitude of these effects are unknown. Most BC is stored in terrestrial systems with some transported to the ocean via rivers and the atmosphere. However, the oceanic BC budget is not balanced, with known BC removal fluxes exceeding BC inputs. We demonstrate these observed inconsistencies using a simple ocean box model, which highlights key areas of future research. Measurements of BC mineralization and export rates along the land-to-ocean continuum and quantification of previously unexplored sources of oceanic BC are needed to close the global BC budget.
Key points
- Black carbon (BC) is produced from incomplete combustion of biomass and fossil fuels and persists for centuries to millennia in the environment.
- BC production is expected to increase with increasing fire activity under anthropogenic warming and could act as a negative feedback to climate change.
- BC is often divided into particulate and dissolved BC, which can have different environmental transport mechanisms, residence times and fates.
- The largest BC pool is in the soil (160–200 petagrams (Pg) C globally). Rivers transport 43 ± 15 teragrams (Tg) BC per year; BC is cycled in other inland aquatic systems, but the global relevance of these processes is unknown.
- Oceans store 12–14 Pg C of dissolved BC. The observed age of this BC (4,800 ± 620 14C years in the surface ocean, >20,000 14C years in the deep ocean) does not match expected ages based on mass balance estimates.
- Future research must further explore the possibility that some of the dissolved BC in marine waters is not derived from terrestrial fires.
Dennis Amoroso
Thank you for keeping our feet on the ground!
On Aug 9, 2022, at 5:10 AM, Tom Goreau <gor...@globalcoral.org> wrote:
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