I am on assignment a large part of my time and therefore it is very difficult to answer comments and emails. I apologize for being unreachable, but I sincerely hope that some of the people below might be able to help you.
For my commercial representation:
Alice Keating, National Geographic, Alice.Keating@natgeo.com / (202) 857-7237
For stock image sales:
Stacy Gold at National Geographic Creative, Stacy.Gold@natgeo.com / (202) 857-7537 or 1-800-434-2244
For speaking opportunities:
National Geographic Speaker's Bureau, (202) 775–7800, or send an email to email@example.com
For everything else: firstname.lastname@example.org