When he invites you to share his lunch with him, he beckons one of his assistants to mix an extra packet of chocolate protein powder with warm water in a Dixie cup.
"The first thing that happens when we add carbon dioxide into the atmosphere is it radiates some extra radiation back down to the surface, and we warm up a little bit, " Kirk-Davidoff says.
Even though the day is bright and warm, I ask you to indulge me to spend a few extra moments to think about what it means that we here, today, to mark the final Memorial Day of this century.