British English subtitles for clip: File:Klimafaktor CO₂ (ZDF, Terra X) 720p HD 50FPS.webm

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[Greenhouse gas CO₂]
[Content in the atmosphere: 415 ppm]

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[From industrialization: 280 ppm]
[Emissions per year: 40 gigatons]

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With the use of coal, oil and gas,
humans currently blow

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around 40 gigatons of carbon dioxide
into the atmosphere each year.

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With 415 ppm - i.e. 415 CO₂ molecules
per million air molecules -

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the concentration
is about 40 percent higher

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than it was around the middle
of the 19th century,

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before industrialization.

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But how does CO₂
cause the greenhouse effect?

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Part of the sunlight - here yellow -
is reflected directly,

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for example from ice surfaces.

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Another part is converted
into invisible heat radiation - here red.

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This radiation cannot leave
the atmosphere unhindered.

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They capture greenhouse gases
and partly throw them back to earth -

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a kind of ping-pong effect.

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In an experiment,
atmospheric physicist Stephan Borrmann

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makes the greenhouse effect visible.

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Also helping: the student Svenja Kennt.

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The sun, in the model
a lamp, heats up the earth.

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Like the land and the oceans,
the black band absorbs the radiation

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and converts it into heat.

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A quick heat check:
the thermometer shows 80 degrees.

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Heat that is emitted again and measured
by a special infrared sensor.

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The vessel in between is filled with air, 
the atmosphere of the earth, so to speak.

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"Now we can interrupt this radiation

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by simply holding a piece of paper
in between, for example."

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The heat radiation is blocked by the paper

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and no longer reaches
the measuring device.

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The pointer goes to zero.

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"Now we just fill this atmosphere
with a greenhouse gas,

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namely carbon dioxide,
through a hose from the bottle."

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For all skeptics: This is about
the principle of the greenhouse effect,

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not the simulation of real conditions,
which is not possible in a test tube.

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The experiment shows

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that the CO₂ in the "atmosphere"
intercepts the radiation.

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In a second experiment,

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a highly specialized thermal
imaging camera is used.

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It’s particularly sensitive
to part of the wavelength range,

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which is relevant among other things
for the greenhouse effect of CO₂.

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The camera registers
the heat radiation from a candle.

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As with the first attempt,
pure CO₂ is filled into the equipment,

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so that the effects of CO₂
can be made visible in principle.

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Here, too, the CO₂
absorbs the heat radiation

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and the image of the special camera
goes dark,

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although the candle continues to burn
normally at the other end of the apparatus

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and radiates heat.

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But does the same happen with other gases?

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If the CO₂ in the tube
is replaced by nitrogen,

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the image on the monitor
slowly builds up again.

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That means nitrogen does not absorb heat.

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Conclusion:

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In the atmosphere, the greenhouse effect

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would be weakened
by reduced CO₂ emissions.