b) The IPCC - https://www.ipcc.ch/about/
Please decide who would have the most legitimacy in what they write and if you agree that the IPCC collective of hundreds of scientists is noteworthy, then please read the 6th report issued by the IPCC.
I link below the summary:
https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6...