The mechanism slightly differs: Greenhouse gases like CO2 ABSORB infrared light (that is the warming effect), which is part of the solar radiation spectrum as well as of the backscattered spectrum, re-radiated from the terrestrial surface. However, large proportions of the incoming solar radiation (UV, visible light) are also changed to infrared on Earth's surface - thus leading to a misbalance of incoming and outcoing IR radiation. The resulting effect is a net global warming of the planet compared to a model planet without greenhouse gases.

Nevertheless, the warming effect is counterbalanced by cooling effects from certain aerosols (e.g. sulphates from combustion) or - in advance - by shading effects of certain cloud types or by bright surface albedos - thus giving ground for corresponding climate engineering concepts. However, the overall natural cooling effects are quantitatively less effective than the  greenhouse effect, to date.

Yes Stephan,

It is absorption of incoming solar radiation by CO2 which causes radiative forcing and hence a higher atmospheric temperature on Earth. Additionally, though CO2 is an important radiative forcing agent in the atmosphere of the Earth it certainly is not the only one.

Greenhouse gases (sometimes abbreviated GHGs) are gases in the atmosphere that absorb AND emit radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect.

The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Greenhouse gases strongly affect the temperature of the Earth; without them, the Earth's surface would average about 33 °C colder, below the present (global) average of 14 °C.

A ((mostly) corroborated) hypothesis in Climate Change is that the greenhouse gases  CO2, CH4 and NO alter the Earth's climate due to their increasing emission (and hence imission) levels and reduced uptake (of CO2) by vegetation (mainly (tropical) forests). A feed forward mechanism may cause an amplification of the greenhouse effect due to an increased mixing ratio of water vapor in a warmer atmosphere (larger capacity for absolute gaseous water content) . This can trigger cloudiness changes as well.

Nobody said that it is easy to understand and especially simulate and predict Climate Change and the role of feedback and feed forward mechanisms. Especially the limits of the different atmospheric constituents where climate would show a runaway behavior are till now unknown. Reason enough to be careful with deforestation and increasing greenhouse gas emissions. Till now, humanity is still in a business as usual scenario.

Cheers,

Frank

Check out the attached review paper that touches on this issue. Also, the first paper that addressed this issue using a climate model.

Article The Science of Geoengineering

Article Geoengineering Earth's energy balance to mitigate CO2-induce...

It is not generally known that the greenhouse effect was first shown to exist by Horace Benedict de Saussure in the 18th Century. At that time scientist were trying to explain why mountain tops are covered in snow and ice. It was known that the Sun is responsible for the warmth of the Earth, and it was a mystery why the mountains which intersect the Sun's rays first were cooler.

Based on an idea proposed by Pierre Bouguer, de Saussure proposed that the atmosphere is transparent to solar radiation, but absorbs the "obscure heat" emitted by the surface of the Earth. He showed the existence of the obscure heat using two large concave metal mirrors to reflect the heat from a heated cannon ball onto a thermometer. His discovery of infrared radiation preceded that of Herschel, who mentions Saussure's experiment, by approximately twenty years.

Saussure also used a hotbox to measure the heat from the Sun high on a mountain, and also in a valley below and found that very little difference in the temperature of the air in the hotbox when measured at those two sites, implying that solar radiation is not absorbed in the atmosphere.

Joseph Fourier claimed that Saussure had shown that the atmosphere behaves like a hot box, but that is wrong. Saussure had only used his hotbox, which he called a helio-thermometer, to show that solar radiation is not absorbed. Later, Arrhenius described the phenomenon as a hot house effect which evolved into the greenhouse effect.

I have translated the relevant chapter of Saussure's book here:

Working Paper "Travels in the Alps" Volume 2, Chapter 35 by H-B de Saussur...

and his description of the invention of his helio-thermometer can be downloaded from here: https://www.researchgate.net/project/The-Tiamat-Project/update/594d73861042bfede1608418