[D66] Carbon Dioxide — How Can One Little Molecule Be Such a Big Troublemaker? Carbon Dioxide — How Can One Little Molecule Be Such a Big Troublemaker? Carbon Dioxide — How Can One Little Molecule Be Such a Big Troublemaker?

[Henk Elegeert]

http://news.thomasnet.com/green_clean/2012/03/06/carbon-dioxide-how-can-one-little-molecule-be-such-a-big-troublemaker/
Carbon Dioxide — How Can One Little Molecule Be Such a Big Troublemaker?

Why do climate scientists place so much importance on the role of carbon
dioxide (CO2) in human-caused global warming? Isn’t CO2 just a trace gas?
After all, CO2 molecules are only about 390 out of every million molecules
of air (that is, 390 parts per million, or ppm). How could a gas with such
small concentration cause the earth’s temperatures to rise and cause all
the calamities the alarmists are warning about?

A report from the National Academy of
Sciences<http://dels.nas.edu/resources/static-assets/materials-based-on-reports/booklets/warming_world_final.pdf>
 asserts:

Emissions of carbon dioxide from the burning of fossil fuels have ushered
in a new epoch during which human activities will largely determine the
evolution of the Earth’s climate. Because carbon dioxide is long-lived in
the atmosphere, increases in this key gas can effectively lock the Earth
and many future generations into a range of impacts, some of which could be
severe. Therefore, emission reduction choices made today matter in
determining impacts that will be experienced not just over the next few
decades, but also into the coming centuries and millennia.

Climate-change critic Gregg D. Thompson
counters<http://www.theonelightgroup.com/latest/what-do-you-know-about-co2-and-climate-change>
that
CO2 constitutes only 0.039 percent of air. “CO2 is a harmless, trace gas.
It is necessary for life – just as oxygen and nitrogen are. It is a natural
gas that is clear, tasteless and odorless,” Thompson writes. “It is in no
way a pollutant.”
What is it about this molecule that causes such a fuss?

Climate scientists focus on carbon dioxide because it is a greenhouse gas
and contributes to the greenhouse effect. The use of the word “greenhouse”
in this context is useful on the one hand, but on the other hand is a
little misleading. The transparent glass in a greenhouse roof lets solar
radiation into the building. In a similar way, the earth’s transparent
atmosphere lets solar radiation make it down to the earth’s surface.
*(Illustration
credit: ZooFari <http://commons.wikimedia.org/wiki/User:ZooFari>, CC BY-SA
3.0 <http://creativecommons.org/licenses/by-sa/3.0/deed.en>)*

[image: Illustration of greenhouse effect]

Both systems — the glass greenhouse and the earth’s greenhouse effect —
trap heat and keep the occupied space warm. But they do so for different
reasons. The glass greenhouse traps warm air that has been heated by the
solar radiation; without the glass, the warm air would rise and blow away.
But the earth’s atmosphere doesn’t just hold warm air; it actually absorbs
the radiation; molecules in the atmosphere take in the energy being
radiated up from the earth’s surface.

In reality, the earth’s greenhouse effect is a good thing. If not for the
greenhouse effect, earth’s average surface temperature would be -18°C
(Celsius), or -40°F (Fahrenheit). Instead, our planet exists at a livable
15°C, or 59°F. Climate scientists have concluded, though, that human
activity is increasing the greenhouse effect and that this could have
negative effects on the planet’s living conditions.
So how does it work? How does CO2 trap radiation?

Put simply, carbon dioxide likes a certain kind of radiation and is very
good at capturing it.

[image: Chart showing the electromagnetic spectrum]The sun emits
electromagnetic radiation of all wavelengths. About 50 percent of the sun’s
radiation is visible light; the spectrum of visible light goes from .4
microns to .7 microns (abbreviated as µm, a micron being a micro-meter or
one-millionth of a meter). Radiation, including visible light, travels in
waves; wavelength is the distance from the crest of one wave to the crest
of the next. The visible light spectrum, which you can observe in a rainbow
or a prism, goes from violet at .4 µmthrough blue, green, yellow, orange,
to red at .7 µm.; .4 µm is a shorter wavelength, .7 µm is a longer
wavelength. *(Chart credit:Wikimedia
Commons<http://en.wikipedia.org/wiki/Electromagnetic_spectrum>
, CC BY-SA 2.5 <http://creativecommons.org/licenses/by-sa/2.5/deed.en>)*

About 10 percent of the sun’s radiation, that radiation below the visible
spectrum, is shorter-wavelength, or ultraviolet principally. The rest,
about 40 percent, is above the visible spectrum, mostly longer-wavelength
infrared radiation.

So the sun is constantly blasting the earth with all of this radiation
across the spectrum, especially visible and infrared. The energy that makes
it to the earth’s surface gets absorbed and then radiated back out. The
greenhouse effect works in part because the earth is much cooler than the
sun, so when the earth radiates, it tends to send out lower-energy,
longer-wavelength infrared radiation.

Greenhouse gases, especially CO2 and water vapor, are very good at
absorbing infrared radiation, particularly around 15 µm. Eventually, almost
all of the radiation in the earth’s atmosphere gets re-radiated back out
into space, but the greenhouse gases hold it in long enough to generate a
greenhouse effect in the planet’s atmosphere and keep us at a toasty
15°C. *(Chart
credit: NASA, via Wikimedia
Commons<http://en.wikipedia.org/wiki/Electromagnetic_spectrum>
)*

[image: Chart showing atmospheric electromagnetic opacity across the
spectrum]
What’s going on in a CO2 molecule when it absorbs energy?

David Archer<http://cis.uchicago.edu/outreach/summerinstitute/2008/documents/archer1.pdf>,
professor of Geophysical Sciences at the University of Chicago,
writes<http://forecast.uchicago.edu/archer.ch4.greenhouse_gases.pdf>
:

Gases are the simplest type of molecule, and they only vibrate in very
particular ways. Vibrations in a gas molecule are like vibrations of a
piano string in that they are fussy about frequency. This is because, like
a piano string, a gas molecule will only vibrate at its “ringing” frequency.

When you get down to the molecular level, it becomes useful to think of
radiation as traveling in pulses, or “photons.” When a photon hits a
molecule, it can cause it to vibrate, to take on the photon’s energy,
absorbing it. CO2 vibrates by bending in the direction of the arrows shown
in the following illustation. Not just any old photon can get absorbed by a
CO2 molecule — it has to be a photon of radiation within certain
wavelengths. Any photon that is not within those relatively narrow
wavelengths will just pass by the CO2 molecule and go look for some more
congenial greenhouse gas to take up with, or maybe just mosey on up into
space.

[image: Drawing of a CO2 molecule]

The ESPERE <http://www.espere.net/index.html> (Environmental Science
Published for Everybody ‘Round the Earth) web site provides a helpful
analogy <http://www.espere.net/Unitedkingdom/water/uk_absorption.htm> that
helps explain how energy absorption by greenhouse gases works.

Imagine that you are playing miniature golf, and you come to one of those
maddening holes where the cup is right at the peak of a hill. If you putt
the ball too softly, it will roll back down the hill and everyone will
laugh at you. If you putt the ball too hard, it will skip over the hole,
resulting in more hilarity. But if you putt the ball with just the right
force, it will drop neatly into the cup at the top of the hill, and
everyone will admire you.

[image: Drawing of the mini-golf analogy]

In a similar way, only photons with certain energy characteristics can be
absorbed by a molecule of carbon dioxide (or any other greenhouse gas).

The greenhouse gases receive a constant bombardment of infrared radiation
emitted from the earth. Their molecules vibrate, heating up the air.

Carbon dioxide is only one of the greenhouse gases — water vapor, methane,
nitrous oxide, ozone, and freon-11 and -12 are greenhouse gases as well.
However, CO2 stays in the atmosphere longer than the others. For example,
water vapor is the most abundant greenhouse gas, but it condenses and only
stays in the atmosphere for a few days, so it doesn’t build up in the
atmosphere as CO2 does. The Union of Concerned Scientists
(UCS)<http://www.ucsusa.org/global_warming/science_and_impacts/science/CO2-and-global-warming-faq.html>
 says:

In the case of CO2, much of today’s emissions will be gone in a century,
but about 20 percent will still exist in the atmosphere approximately 800
years from now. This literally means that the heat-trapping emissions we
release today from our cars and power plants are setting the climate our
children and grandchildren will inherit.

The following chart from the UCS shows that, of all human causes, CO2
emissions exert the most influence on global warming.
[image: Chart showing relative forcings of human-induced climate drivers]

Chart courtesy of Union of Concerned Scientists

Climate scientists are concerned that CO2 concentrations in the atmosphere
have risen from 280 ppm in pre-industrial times to 390 ppm today. That
increased concentration has caused an imbalance in the greenhouse effect,
so that the atmosphere is capturing a little extra energy each year,
raising global surface temperatures.

Research by NASA’s Goddard Institute for Space Studies (GISS) has
identified CO2 as “The Thermostat That Controls Earth’s Temperature.” A
science brief by NASA scientist Andrew
Lacis<http://www.giss.nasa.gov/research/briefs/lacis_01/index.html>
emphasizes
that, while both water and CO2 are greenhouse gases, they provide different
functions in the maintenance of the greenhouse effect. Water vapor
condenses, whereas CO2, methane, ozone, and the other trace gases are
non-condensing. Lacis writes:

[W]ater vapor accounts for about 50% of the Earth’s greenhouse effect, with
clouds contributing 25%, carbon dioxide 20%, and the minor greenhouse gases
(GHGs) and aerosols accounting for the remaining 5%… Thus, while the
non-condensing greenhouse gases account for only 25% of the total
greenhouse effect, it is these non-condensing GHGs that actually control
the strength of the terrestrial greenhouse effect since the water vapor and
cloud feedback contributions are not self-sustaining and as such, only
provide amplification. Because carbon dioxide accounts for 80% of the
non-condensing GHG forcing in the current climate atmosphere, atmospheric
carbon dioxide therefore qualifies as the principal control knob that
governs the temperature of Earth.

So how can a trace gas that makes up only 390 ppm of the earth’s atmosphere
(that is, after all, only .04 percent) possibly make any difference? The
upshot is that even a relatively small concentration of a substance can
have a large impact, especially at large scales and over longer time
periods.
"

Ok, ook in 'geloven' maakt de lichtste twijfel meteen een eind aan de/alle
zekerheid, maar wat nu is precies de 'large impact' ?

En...: is 'kunnen hebben'  ook een wetenschappelijk bewijs? Kortom: hoe zit
dat nu met dat: "HOE" ?

Henk Elegeert

Biltse professor heeft oplossing broeikasprobleem
http://www.youtube.com/watch?v=EYLAHFz9WqQ

... maar, hebben we überhaupt wel een echt / echt een broeikasprobleem?
Evenzogoed, hoe is - in geval dat - het probleem nu werkelijk opgelost,
immers: 'even a relatively small concentration of a substance can have a
large impact'!!
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