FW: Forest fire Black carbon as a positive climate feedback

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Tom Goreau

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Aug 9, 2022, 11:45:05 AM8/9/22
to soil-age, Russ Speer

 

  • 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 mollisolchernozem, 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

Nature Reviews Earth & Environment volume 3pages516–532 (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.

 

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Nan Hildreth

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Aug 9, 2022, 1:27:10 PM8/9/22
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A major source of black carbon is from household energy use in low income countries.   They use extremely cheap and inefficient tools to cook and light.   This is as bad for them as for our climate.    Of all the climate actions, this is low hanging fruit.   Very effective for little effort.   A UN Sustainable Development Goal is to upgrade them

Kerosene lamps are used by folks without any electricity and they are very, very smokey.  About 700 million people still don't have grid or solar electricity.    A $50 solar lamp will pay for itself because they can quit buying so many quarts of expensive kerosene.  Solar light is brighter, cleaner, cheaper.   In many areas, folks are switching, but Africa and parts of Asia,  need some help with this.    The good news is in the last decade or so, maybe 40% of these folks got some electricity. 

Half of humanity cooks with firewood and half of them use hand-made and inefficient stoves.   A $25 to $100 factory made stove is so much more efficient, it will cut their firewood use in half or more.   Upgrading them is very good for the people too.  Less time or expense in getting fuel.  Less smoke to breathe during cooking. 

A more efficient little stove means lots less black carbon emissions.    Project Drawdown found that improved stoves will help about as much as rooftop solar

My favorite nonprofit doing last-mile distribution of these gadgets is Solar Sister.   Regeneration.org lists some of the groups working on this.   The UN's Clean Cooking Alliance networks and supports them. 

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