It seems like the global warming discussion is just one of those discussions that can only be settled with a bet, but what is the bet? I would be very grateful if you would help me with the following questions:

1. Could somebody who do not believe global warming is ocurring tell me what fact would lead them to conclude that they've lost the bet?

2. Could someone who do not believe global warming is caused by humans tell me what fact would lead them to conclude that they've lost the bet?

Looking forward to your answers - and to make some easy money...