[ExI] WSJ Article: "In Defense of CO2"

[Kevin G Haskell]

"In Defense of Carbon Dioxide" - WSJ

"By HARRISON H. SCHMITT AND WILLIAM HAPPER

Of all of the world's chemical compounds, none has a worse reputation than
carbon dioxide. Thanks to the single-minded demonization of this natural
and essential atmospheric gas by advocates of government control of energy
production, the conventional wisdom about carbon dioxide is that it is a
dangerous pollutant. That's simply not the case. Contrary to what some
would have us believe, increased carbon dioxide in the atmosphere will
benefit the increasing population on the planet by increasing agricultural
productivity.

The cessation of observed global warming for the past decade or so has
shown how exaggerated NASA's and most other computer predictions of
human-caused warming have been—and how little correlation warming has with
concentrations of atmospheric carbon dioxide. As many scientists have
pointed out, variations in global temperature correlate much better with
solar activity and with complicated cycles of the oceans and atmosphere.
There isn't the slightest evidence that more carbon dioxide has caused more
extreme weather.

The current levels of carbon dioxide in the earth's atmosphere, approaching
400 parts per million, are low by the standards of geological and plant
evolutionary history. Levels were 3,000 ppm, or more, until the Paleogene
period (beginning about 65 million years ago). For most plants, and for the
animals and humans that use them, more carbon dioxide, far from being a
"pollutant" in need of reduction, would be a benefit. This is already
widely recognized by operators of commercial greenhouses, who artificially
increase the carbon dioxide levels to 1,000 ppm or more to improve the
growth and quality of their plants.

Using energy from sunlight—together with the catalytic action of an ancient
enzyme called rubisco, the most abundant protein on earth—plants convert
carbon dioxide from the air into carbohydrates and other useful molecules.
Rubisco catalyzes the attachment of a carbon-dioxide molecule to another
five-carbon molecule to make two three-carbon molecules, which are
subsequently converted into carbohydrates. (Since the useful product from
the carbon dioxide capture consists of three-carbon molecules, plants that
use this simple process are called C3 plants.) C3 plants, such as wheat,
rice, soybeans, cotton and many forage crops, evolved when there was much
more carbon dioxide in the atmosphere than today. So these agricultural
staples are actually undernourished in carbon dioxide relative to their
original design.

At the current low levels of atmospheric carbon dioxide, rubisco in C3
plants can be fooled into substituting oxygen molecules for carbon-dioxide
molecules. But this substitution reduces the efficiency of photosynthesis,
especially at high temperatures. To get around the problem, a small number
of plants have evolved a way to enrich the carbon-dioxide concentration
around the rubisco enzyme, and to suppress the oxygen concentration. Called
C4 plants because they utilize a molecule with four carbons, plants that
use this evolutionary trick include sugar cane, corn and other tropical
plants.

Although C4 plants evolved to cope with low levels of carbon dioxide, the
workaround comes at a price, since it takes additional chemical energy.
With high levels of carbon dioxide in the atmosphere, C4 plants are not as
productive as C3 plants, which do not have the overhead costs of the
carbon-dioxide enrichment system.

That's hardly all that goes into making the case for the benefits of carbon
dioxide. Right now, at our current low levels of carbon dioxide, plants are
paying a heavy price in water usage. Whether plants are C3 or C4, the way
they get carbon dioxide from the air is the same: The plant leaves have
little holes, or stomata, through which carbon dioxide molecules can
diffuse into the moist interior for use in the plant's photosynthetic
cycles.

The density of water molecules within the leaf is typically 60 times
greater than the density of carbon dioxide in the air, and the diffusion
rate of the water molecule is greater than that of the carbon-dioxide
molecule.

So depending on the relative humidity and temperature, 100 or more water
molecules diffuse out of the leaf for every molecule of carbon dioxide that
diffuses in. And not every carbon-dioxide molecule that diffuses into a
leaf gets incorporated into a carbohydrate. As a result, plants require
many hundreds of grams of water to produce one gram of plant biomass,
largely carbohydrate.

Driven by the need to conserve water, plants produce fewer stomata openings
in their leaves when there is more carbon dioxide in the air. This
decreases the amount of water that the plant is forced to transpire and
allows the plant to withstand dry conditions better.

Crop yields in recent dry years were less affected by drought than crops of
the dust-bowl droughts of the 1930s, when there was less carbon dioxide.
Nowadays, in an age of rising population and scarcities of food and water
in some regions, it's a wonder that humanitarians aren't clamoring for more
atmospheric carbon dioxide. Instead, some are denouncing it.

We know that carbon dioxide has been a much larger fraction of the earth's
atmosphere than it is today, and the geological record shows that life
flourished on land and in the oceans during those times. The incredible
list of supposed horrors that increasing carbon dioxide will bring the
world is pure belief disguised as science.

Mr. Schmitt, an adjunct professor of engineering at the University of
Wisconsin-Madison, was an Apollo 17 astronaut and a former U.S. senator
from New Mexico. Mr. Happer is a professor of physics at Princeton
University and a former director of the office of energy research at the
U.S. Department of Energy.

http://online.wsj.com/article/SB10001424127887323528404578452
483656067190.html?mod=WSJ_Opinion_LEADTop

-- 
 * Tweet me on Twitter! - @*KevinGHaskell
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20130509/ce464882/attachment.html>