One of the key arguments of the IPCC is the term "radiative forcing" which is another description for the ability to store energy.

Storing energy in a material is the basic ability to justify the reality of a "greenhouse effect".

Another the radiation laws:
https://de.wikipedia.org/wiki/Strahlungsgesetze

"The Intergovernmental Panel on Climate Change (IPCC) AR4 report defines radiative forcings as:[4]

'Radiative forcing is a measure of the influence a factor has in altering the balance of incoming and outgoing energy in the Earth-atmosphere system and is an index of the importance of the factor as a potential climate change mechanism. In this report radiative forcing values are for changes relative to preindustrial conditions defined at 1750 and are expressed in Watts per square meter (W/m2).' "
https://en.wikipedia.org/wiki/Radiative_forcing

The reason why I am putting this post in this section is the circumstance that "contrails" are also referred to as "greenhouse gases". Thus, the existance of chemtrails are officially recognized by the IPCC - as "contrails". Also, it seems strange that the "contrail" phenomenon is qualified as "greenhouse gas" - as "slight" is known how it is described by the German version of the following picture (in English) in Wikipedia:

By Leland McInnes, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2501966

The picture below shows the German version of the same picture. It is added with some comments which are worthwhile to look at as the contrails (German word: Luftfahrtkondensstreifen) are also mentioned. The difference to the English version of the picture is the assessment of knowledge of the single "radiative forcing" sources.
https://de.wikipedia.org/wiki/Strahlungsantrieb

For a better understanding of the German version of the picture I have listed some vocabulary for the "Luftfahrtkondensstreifen" (contrails) as follows:

German------------English
hoch----------------high
mittel---------------middle
gering--------------slight
Grad ---------------level
wissenschaftlich---scientific
Verständnis--------Unterstanding

Second picture below (German):
Von Arne Nordmann (norro) - Own drawing, based on Image:600px-Radiative-forcings.svg.png by Leland McInnes. All data ist from the IPCC Fourth Assessment Report Summary for Policymakers., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1784671

There are four aspects to conclude from this mentioning of "contrails" as radiative forcing:
1. "Contrails" are officially agreed upon as a game player of changing the climate.
2. It is agreed upon that there is only slight knowledge of how "contrails" are changing the climate.
3. The door for "public" Geoengineering stays open as there is only "slight" knowledge of how "contrails" are changing the climate.
4. The large historical knowledge of how to change the climate is excluded from this view as the Intergovernmental Panel on Climate Change does not refer to technologies of the past. They have yet to be developed as they don't "exist" yet changing the climate already actively.


"Einen negativen (d. h. kühlenden) Strahlungsantrieb in Höhe von −0,9 W/m² verursachen Aerosole.[6]"
https://de.wikipedia.org/wiki/Strahlungsantrieb
English translation:
"A negative (that means cooling) radiative forcing in the amount of -0,9 W/m² are caused by aerosols." (IPCC)
This could be seen as proof for already ongoing Geoengineering.

Also:
http://climate.envsci.rutgers.edu/climdyn2013/IPCC/IPCC_WGI12-RadiativeForcing.pdf page 5