[Stoves] Biosphere GHG emissions and cookstoves (Re: Philip Lloyd)

[Traveller]

This is off-topic, and the List Moderator may reject this, but since some
folks are still intent on GHG beancounting and "climate benefits of
fuel-efficient stoves", this may be of some interest.

The hidden driver of climate change that we too often ignore
<https://www.washingtonpost.com/news/energy-environment/wp/2016/03/09/the-hidden-driver-of-climate-change-that-we-too-often-ignore/?>
(Washington
Post, 9 March 2016).

It cites
<https://www.researchgate.net/publication/297678159_The_terrestrial_biosphere_as_a_net_source_of_greenhouse_gases_to_the_atmosphere>
a paper in Nature whose abstract says, "This results in a net positive
cumulative impact of the three greenhouse gases on the planetary energy
budget, with a best estimate (in petagrams of CO2 equivalent per year) of
3.9 ± 3.8 (top down) and 5.4 ± 4.8 (bottom up) based on the GWP100 metric
(global warming potential on a 100-year time horizon).." The uncertainty
interval is of the same range as I had seen for terrestrial sink in IPCC
reports (Second, Third, Fourth). See the graphic here
<http://www.nature.com/nature/journal/v531/n7593/carousel/nature16946-f1.jpg>.
It "finds that the Earth’s land “biosphere” — defined as all the plants,
animals and microorganisms living on the surface of the Earth (excluding
the oceans) — is now a “net source” of greenhouse gases to the atmosphere.
Thus, the biosphere is now adding to global warming in much the same way
that all of our fossil fuels are."

My haphazard speculations:

1. I don't know much about "much the same way". Atmospheric pathways of
different emitted species may have some local influences of air chemistry,
moisture, temperature - a  methane molecule here is the same anywhere else
but may take different time to turn to CO2 molecule - and the composition
of fossil fuels emissions depends on the combustion process. (Using full
combustion emission factors is a lie, but then again, who knows how good
the data are on fossil fuel combustion by location and combustion
conditions?)

2. Natural methane emissions depend on ambient conditions, see here
<http://www.jerome-chappellaz.com/files/publications/the-relative-importance-of-methane-sources-and-sinks-over-the-last-interglacial-period-and-into-the-last-glaciation-145.pdf>.


3. In general, uncertainties in GHG balances are in the range of billions
of tons of CO2e, though of course some people see every fossil CO2 molecule
as a WMD.) In any case, I think the use of 100-year GWP is an arbitrary
politicized choice; a 20-year GWP is more useful for planning in terms of
population cohorts rather than for eternity.

As far as I know, the atmosphere doesn't care where the carbon comes from,
and allocating blame by source or country is a political choice.

Ronald Reagan was correct - when it comes to CO2, "trees pollute". :-)

4. Inspired by Kirk Smith, I have written advocacy arguments for modern
cooking and "climate benefits". I still believe in the general point that
modern energy transition is good for people and can enhance their
productivities and resilience to climate vulnerabilities. This doesn't have
beans to do with how much GHG reduction any particular activity entails,
but if we are going to play that game, reduction in PIC (products of
incomplete combustion, cooking or otherwise) ranks pretty high in terms of
cost-effectiveness of GHG control options. Kirk Smith now says
<http://www.kirkrsmith.org/publications/2016/5/12/1987-biofuels-air-pollution-and-health-a-global-review-kirk-r-smith>
the climate argument was "a bit of a red herring", but I continue to
believe "All emissions and all impacts considered, modern energy transition
for the poor is good for people and the climate."

Those keen to push biomass stoves because trees sequester carbon (even
though traditional biomass combustion is not carbon-neutral), see Trees on
farms: the missing link in carbon accounting
<http://blog.worldagroforestry.org/index.php/2016/07/20/trees-on-farms-the-missing-link-in-carbon-accounting/>,
based on this paper <http://www.nature.com/articles/srep29987>.

Nikhil

---------
(India +91) 909 995 2080
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