If it could be proven that we are in the warmest period in the past 100,000 years and all natural causes are ruled out
Pretty weak criteria since as you say nothing can be "proven" to someone that doesn't want to believe it.
What I gave you are demonstrable criteria that are achievable within the next ten years. So in other words there is nothing that can happen short of a 10 meter sea level rise in the next ten years that would convince you that maybe there was something to this AGW thing after all?
That's fine because it gives folks an idea about our relative willingness to consider that we might be wrong. I'm willing to accept that I might be wrong based on reasonable criteria within ten years. You're willing to accept that you might be wrong if the hand of god comes down from heaven and sticks a finger up your ass. How's that for an analogy?
If you really do have 10k burning a hole in your pocket
$10K is chump change, just enough to make it interesting. But I haven't really settled on a decent bet that wouldn't take a stupid number of years to collect on. I'm thinking of something like I win if there's a new warmest year on record within the next 5 years if not then I lose, but that's probably a risky bet. The idea is to make a bet that if you believe current AGW projections then the bet is 20 to 1 in your favor but if you don't believe it then it's 20 to 1 in the opposite direction. That would be something both sides should be able to agree on assuming someone is willing to put their money where their mouth is.
There are ridiculous online sucker bets like AGW is "proven" true next year with the caveat that no amount of "proof" other than 30 meters of water over Washington DC would ever convince folks like Inhofe.
send $10k to strangers on the internet
That's why someone like Brad holding the bet is reasonable since he is a public figure, not a stranger on the internet.
That means that it doesn't need to get hotter than it has ever been in the last 100,000 years for us to see sea level rises in the "meters".
We've had at sea level rises of 6 *meters* in the last 120,000 years. That's almost 20 feet.
"During the previous interglacial about 120,000 years ago, sea level was for a short time about 6 m higher than today, as evidenced by wave-cut notches along cliffs in the Bahamas." http://en.wikipedia.org/wiki/Current_sea_level_rise