It’s really quite simple Sco-Mo. Someone, in this case a key international organisation seeking to save the planet, invites you to a world conference. It is polite to respond with your RSVP, particularly when you are advised of the event with perhaps a year’s notice. You say thank you for inviting me, I would be pleased to attend and look forward to further information so I can be well prepared to participate.
Anything less is just rude Scott. They are still waiting for your reply. You continue to live your life at 5 minutes to midnight and prioritise political advantage.
Awesomely Astute 