Carbon dioxide: The “gas of life”
Tiny amounts of this miracle molecule make life on Earth possible
Paul Driessen
*************************
It’s
amazing that minuscule bacteria can cause life-threatening diseases and
infections – and miraculous that tiny doses of vaccines and antibiotics
can safeguard us against these deadly scourges. It is equally
incredible that, at the planetary level, carbon dioxide is a miracle
molecule for plants – and the “gas of life” for most living creatures on
Earth.
In units of volume, CO2’s concentration is typically presented as 400 parts per million (400 ppm).
Translated, that’s just 0.04% of Earth’s atmosphere – the equivalent of
40 cents out of one thousand dollars, or 1.4 inches on a football
field. Even atmospheric argon is 23 times more abundant: 9,300 ppm. Moreover, the 400 ppm in 2013 is 120 ppm more than the 280 ppm
carbon dioxide level of 1800, and that two-century increase is
equivalent to a mere 12 cents out of $1,000, or one half-inch on a
football field.
Eliminate
carbon dioxide, and terrestrial plants would die, as would lake and
ocean phytoplankton, grasses, kelp and other water plants. After that,
animal and human life would disappear. Even reducing CO2 levels too much
– back to pre-industrial levels, for example – would have terrible
consequences.
Over the past two
centuries, our planet finally began to emerge from the Little Ice Age
that had cooled the Earth and driven Viking settlers out of Greenland.
Warming oceans slowly released some of the carbon dioxide stored in
their waters. Industrial Revolution factories and growing human
populations burned more wood and fossil fuels, baked more bread, and
brewed more beer, adding still more CO2 to the atmosphere. Much more of
the miracle molecule came from volcanoes and subsea vents, forest fires,
biofuel use, decaying plants and animals, and “exhaust” from living, breathing animals and humans.
What a difference that extra 120 ppm
has made for plants, and for animals and humans that depend on them.
The more carbon dioxide there is in the atmosphere, the more it is
absorbed by plants of every description – and the faster and better they
grow, even under adverse conditions like limited water, extremely hot
air temperatures, or infestations of insects, weeds and other pests. As
trees, grasses, algae and crops grow more rapidly and become healthier
and more robust, animals and humans enjoy better nutrition on a planet
that is greener and greener.
Efforts
to feed seven billion people, and improve nutrition for more than a
billion who are malnourished, are steadily increasing the tension
between our need for land to feed humans – and the need to keep land in
its natural state to support plants and wildlife. How well we are able
to increase crop production from the same or less acreage may mean the
difference between global food sufficiency and rampant human starvation
in coming decades – and between the survival and extinction of many
plant and animal species.
Modern
agricultural methods steadily and dramatically improved crop yields per
acre between 1930 and today. That is especially important if we
continue to divert millions of acres of farmland from food crops, and
convert millions of acres of rainforest and other wildlife habitat to
cropland, for biofuel production to replace fossil fuels that we again have in abundance. Carbon dioxide will play a vital role in these efforts.
Increased
CO2 levels in greenhouses dramatically improve plant growth, especially
when temperatures are also elevated; rising atmospheric carbon dioxide
levels have likewise had astounding positive impacts on outdoor plant
growth and survival. Lentils and other legumes grown in hothouses with
700 ppm CO2 improved their total biomass by
91%, their edible parts yield by 150 % and their fodder yield by 67%,
compared to similar crops grown at 370 ppm carbon dioxide, Indian researchers found.
Rice grown at 600 ppm
CO2 increased its grain yield by 28% with low applications of nitrogen
fertilizer, Chinese scientists calculated. U.S. researchers discovered
that sugarcane grown in sunlit greenhouses at 720 ppm
CO2 and 11 degrees F (6 degrees C) higher than outside ambient air
produced stem juice an amazing 124% higher in volume than sugarcane
grown at ambient temperature and 360 ppm carbon dioxide. Non-food crops like cotton also fare much better when carbon dioxide levels are higher.
Research
into natural forest and crop growth during recent periods of rising
atmospheric carbon dioxide levels, between 1900 and 2010, found
significant improvements under “real-world” conditions, as well.
An
analysis of Scots pines in Catalonia, Spain showed that tree diameter
and cross-sectional area expanded by 84% between 1900 and 2000, in
response to rising CO2 levels. The growth of young Wisconsin trees
increased by 60%, and tree ring width expanded by almost 53%, as
atmospheric carbon dioxide concentrations increased from 316 ppm in 1958 to 376 ppm in 2003, researchers calculated.
University
of Minnesota scientists compared the growth of trees and other plants
during the first half of the twentieth century (which included the
terrible Dust Bowl years), when CO2 levels rose only 10 ppm – to the period 1950-2000, when CO2 increased by 57 ppm.
They found that carbon dioxide lowered plant sensitivity to severe
drought and improved their survival rates by almost 50%. Swiss
researchers concluded that, because of rising carbon dioxide levels,
“alpine plant life is proliferating, biodiversity is on the rise, and
the mountain world appears more productive and inviting than ever.”
Other
researchers used historical (real-world) data for land use, atmospheric
CO2 concentration, nitrogen deposition, fertilization, ozone levels,
rainfall and climate, to develop a computer model that simulates plant
growth responses for southern US habitats from 1895 to 2007. They
determined that “net primary productivity” improved by an average of
27% during this 112-year period, with most of the increased growth
occurring after 1950, when CO2 levels rose the most, from 310 ppm in 1950 to 395 ppm in 2007.
How
does all this happen? Plants use energy from the sun to convert carbon
dioxide from the air, and water and minerals from the soil, into the
carbohydrates and other molecules that form plant biomass. More
CO2 means more and larger flowers; higher seed mass and germination
success; and improved plant resistance to droughts, diseases, viruses,
pathogenic infections, air pollutants, and salt or nitrogen accumulation
in soils. Higher CO2 levels also improve plants’ water use efficiency –
ensuring faster and greater carbon uptake by plant tissues, with less
water lost through transpiration.
More
airborne CO2 lets plants reduce the size of their stomata, little holes
in leaves that plants use to inhale carbon dioxide building blocks.
When CO2 is scarce, the openings increase in size, to capture sufficient
supplies of this “gas of life.” But increasing stomata size means more
water molecules escape, and the water loss places increasing stress on
the plants, eventually threatening their growth and survival.
When the air’s carbon dioxide levels rise – to 400, 600 or 800 ppm
– the stomata shrink in size, causing them to lose less water from
transpiration, while still absorbing ample CO2 molecules. That enables
them to survive extended dry spells much better.
(The 2009 and 2011 volumes of the Nongovernmental International Panel on Climate Change report, Climate Change Reconsidered, especially this section, and Dr. Craig Idso’s www.CO2science.org
website summarize hundreds of similar studies of crops, forests,
grasslands, alpine areas and deserts enriched by carbon dioxide. CO2
Science’s Plant Growth Database lets people search for more studies.)
One
of the worst things that could happen to our planet and its people,
animals and plants would be for carbon dioxide levels to plunge back to
levels last seen before the Industrial Revolution. Decreasing CO2 levels
would be especially problematical if Earth cools, in response to the
sun entering another “quiet phase,” as happened during the Little Ice
Age. If Earth cools again, growing seasons would shorten and arable
cropland would decrease in the northern temperate zones. We would then
need every possible molecule of carbon dioxide – just to keep
agricultural production high enough to stave off mass human starvation …
and save wildlife habitats from being plowed under to replace that lost
cropland.
However,
even under current Modern Warm Era conditions, crops, other plants,
animals and people will benefit from more carbon dioxide. The “gas of
life” is a miracle plant fertilizer that
helps plants grow and prosper – greening the planet, nourishing
wildlife habitats, feeding people who crave larger amounts of more
nutritious food, preventing species loss, and even warming the Earth a
little.
That is an amazing fete for a colorless, odorless, tasteless gas that comprises just 0.04 percent of our atmosphere! We should praise carbon dioxide – not vilify, ban or bury it.
__________
Paul
Driessen is senior policy analyst for the Committee For A Constructive
Tomorrow. His full report on the magic and mystery of carbon dioxide can
be found at www.CFACT.org. 8/14/13*************************
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