AGW is quite falsifiable, idiot.
1) Show humans are not the source of the increased CO2 in the atmosphere
2) Show that CO2 is not a greenhouse gas
3) Show that the greenhouse effect isn't real
4) Show that the Earth's temperature is not increasing
And when you cannot falsify it, accept the likelihood that it is valid.
I'll add a few more:
5) Show sea level isn't increasing.
6) Show glaciers aren't melting (overall)
7) Show that backradiation isn't increasing.
8) Show there's no stratospheric cooling.
9) Demonstrate conclusively that a specific natural factor is causing the current fast warming
The real irony? Denialism can't be falsified. There is literally no evidence that could disprove it the mind of any denier. Denialism doesn't even rise to the level of pseudoscience, becasue there's no theory at all behind it. If you ask them for their theory of what's causing the current fast warming, you get either conspiracy theories or silence. What you don't get is any actual theory that can be tested.