[News] Greenhouse Gas Carbon Dioxide Ramps Up Aspen Growth

[Moontanman]

Greenhouse Gas Carbon Dioxide Ramps Up Aspen Growth

ScienceDaily (Dec. 4, 2009) — The rising level of atmospheric carbon dioxide may be fueling more than climate change. It could also be making some trees grow like crazy.

 

Greenhouse gas carbon dioxide ramps up aspen growth

[BrianG]

Then CO2 emissions are a good thing, if you like trees.

[CraigD]

Then CO2 emissions are a good thing, if you like trees.

Yes, they are.

 

Increased [ce]CO2[/ce] concentration is good for – that is, increase the growth rate, and increase the concentration of desirable chemicals in their tissues – most plants, but only up to a concentration of about 0.002 (2000 PPM, about 5 times normal). At concentrations over 0.003, [ce]CO2[/ce] is toxic to plants – over a period of days, kills them.

 

[ce]CO2[/ce] is also toxic to animals at high concentrations. The US OSHA maximum safe environmental concentration is 0.005. At about 0.08 (80000 PPM, about 200 times normal), it’ll kill a human within 10 minutes or so.

 

It’s unlikely that atmospheric [ce]CO2[/ce] concentrations could ever be so high on Earth outside of enclosed boxes and rooms with artificial supplies, or rare natural situations where it vents into closed valleys or smaller depressions.

 

For the last 500,000 years or so, average atmospheric [ce]CO2[/ce] concentration varied between roughly 0.0002 and 0.0003. The last 100 years has seen it exceed this range, increase to its present 0.000384, with high-confidence projections that regardless of changes in human-produced carbon output (burning stuff), it will likely continue to increase for at least a few decades. However, even in worst-case scenarios (eg: accelerated deglaciation, rapid global sea level rise, great submarine methane releases), coming [ce]CO2[/ce] concentration will not, I think, increase to levels that are directly hazardous to plants or animals.

 

Hazards to plants and animals due to indirect effects – rising sea levels, climate changes – may be dramatic in the coming decades and centuries. Even more indirect effects – loss of disruption of national governments and economies due to large refugee populations caused by loss of near seal level real estate and agriculture, for example – could be even more hazardous – though are more difficult to scientifically forecast even than future sea levels and climate. It’s a near scientific certainty, however, that we humans won’t be directly, metabolically poisoned by [ce]CO2[/ce], and plants will benefit slightly from metabolically from increased concentration of it.

 

(Sources: wikipedia article “carbon dioxide” and links from it)

[Essay]

Then CO2 emissions are a good thing, if you like trees.

Thanks CraigD, for the figures on CO2; and for the points about life's "supporting" systems in general... and that it's about more than just trees.

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http://www.irri.org/publications/wrrc/wrrcPDF/session19-04.pdf

Effect of elevated CO2 on nutrient uptakeand nutritional conditions of rice

 

Results showed that elevated CO2 affects nutrient up-take and nutritional conditions of rice. Nitrogen content (%) in the rice plants sampled at different growth stages decreased significantly under FACE treatment, but N accumulation increased slightly because of the significant enhancement in dry-matter production. Ear N concentration increased at the heading stage but decreased at the ripening stage. No significant effect was found on root N concentration at tillering, but root N concentration at jointing, heading, and ripening decreased.

... Leaf P concentration at jointing, heading, and ripening increased, but no significant effect was found on P concentration in the stem, ear, and root. P and K concentration in rice was not influenced in the same way as N concentration by elevated CO2. The dilution effect is always used to explain the decrease in N content led by elevated CO2; however, it could not be used to explain the increase in P content.

 

Elevated CO2 effects on plant carbon, nitrogen, and water relations: six important lessons from FACE -- Leakey et al. 60 (10): 2859 -- Journal of Experimental Botany

Journal of Experimental Botany. 60(10):2859-2876.

Elevated CO2 effects on plant carbon, nitrogen and water relations: Six important lessons from FACE [Free-Air Carbon dioxide Enrichment (FACE)]

 

This review describes some of the lessons learned from the long-term investment in these experiments. First, elevated CO2 stimulates photosynthetic carbon gain and net primary production over the long term despite down-regulation of Rubisco activity. Second, elevated CO2 improves nitrogen use efficiency and, third, decreases water use at both the leaf and canopy scale. Fourth, elevated CO2 stimulates dark respiration via a transcriptional reprogramming of metabolism. Fifth, elevated CO2 does not directly stimulate C4 photosynthesis, but can indirectly stimulate carbon gain in times and places of drought. Finally, the stimulation of yield by elevated CO2 in crop species is much smaller than expected. While many of these lessons have been most clearly demonstrated in crop systems, all of the lessons have important implications for natural systems.

 

It's always easy to point to some particular "beneficial" change among the infinity of changes that will accompany any rapid or extreme climate shift; but there are so many more deleterious changes to the established order of our ecosystem-based supporting services, that it's hard to feel good about the few winners in the adaptation game.