[Stoves] Interesting Video

[Gordon West]

Not all “food production” is vegetative, either. I understand that bodies of water are becoming more acidic due to higher atmospheric CO2 levels, which is affecting aquatic life productivity and diversity in a negative way. The simplistic perspective that it’s okay to mess with the complex system of life on the planet because it might increase “food production” for humans does not seem pragmatic to me. I am more likely to believe that natural systems will produce the optimal balance in a complex world of life, than humans “engineering” it for one narrow purpose or another while proceeding in ignorance about everything else.

Gordon 




> On Mar 27, 2018, at 5:01 AM, Andrew Heggie <aj.heggie at gmail.com> wrote:
> 
> On 25 March 2018 at 16:16, Crispin Pemberton-Pigott
> <crispinpigott at outlook.com> wrote:
> 
>> 
>> Sixth, if we were somehow to drive the CO2 down to the pre-industrial low
>> mark, food production on Planet Earth would drop 30%.
> 
> Crispin I'm happy to go along with your first five points but this
> last is misleading in the extreme: whilst it is a fact that elevated
> levels of  CO2 will increase crop yield in certain cases it is not
> true in general, even in those cases where it may be beneficial I can
> find no cites that claim more than 23%.
> 
> In UK I am aware of increases of crop of the potato family, tomatoes
> were routinely grown in heated glass houses with CO2 increased.
> 
> I also played a small part in forest trials in the mid 80s where
> circular plots (which I cleared) in a pine forest were replanted and
> fumigated with different gases, CO2, SO2 and N2 to measure any
> changes.
> 
> This was shortly after the 1979 Charney report which commented on the
> increasing levels of CO2, in the intervening 40 years I don't see much
> to say the predictions were incorrect though personally I didn't
> understand the significance until the middle of this millennium’s
> first decade.
> 
> So my take, and I am not a plantsman nor a biologist and I would have
> hoped that there was someone in that field on this list to comment,
> certain plants have evolved to make better use of CO2, they are
> commonly referred to as C4 plants, because of the more advanced way
> they photosynthesise, these plants use CO2 so much more efficiently
> that any concentrations over 200 parts per million is not advantageous
> to them. They have evolved over millions of years in levels of under
> and about 280 ppm, now we are at about 400 ppm. This group that do not
> benefit from higher than pre industrial levels of CO2 include the food
> crops typically grown in hotter countries:  maize, sugar cane, millet,
> and sorghum.
> 
> The other group of plants generally out competed by the C4 plants in
> hotter drier climates are known as C3 plants. They theoretically can
> benefit from increased CO2 in drier areas because they react to water
> stress by closing their stomata, this reduces their ability to take up
> CO2 into their cells when stressed. Generally these are crops that
> benefit from irrigation, like rice and potatoes. I have seen cites of
> up to 11% increased crop yield being possible  in these plants but
> generally not achieved as other nutrients become limiting,
> particularly nitrogen.
> 
> There have been reports of increases of productivity in non food
> plants up to 23% by Oak Ridge National Laboratory in enhanced CO2 for
> trees but these are overwhelmed by increase of temperature above 30C
> and water stress. In UK summer water deficits limit growth
> increasingly as weather patterns change and the ratio of
> precipitation increases in winter while the total annual rainfall
> remains similar.
> 
> Worse to my mind is the way ocean surface concentrations of CO2 have
> changed so fast in evolutionary terms that marine life has been unable
> to react so there is a net loss of photosynthetic activity  in shallow
> waters.
> 
> Andrew
> 
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