I can't comment on the copyright issues but the ipcc logo comprises the ipcc lettering (not itself a logo) in the frutiger font plus the logos of the two parent organizations WMO and UNEP. The two smaller logos of WMO and UNEP are an integral part of the IPCC logo and quite some effort goes into enforcing this.
This work includes material that may be protected as a trademark in some jurisdictions. If you want to use it, you have to ensure that you have the legal right to do so and that you do not infringe any trademark rights. See our general disclaimer. This tag does not indicate the copyright status of the attached work. A normal copyright tag is still required.See Commons:Licensing.
Captions
The logo of the Intergovernmental Panel on Climate Change
Das Logo des IPCC (Intergovernmental Panel on Climate Change)