Fire events have been decreased a lot - thresholds remain as they seem to work fine.
Chances now lowest to highest flammability: 300, 250, 200, 150, 100 (was 200, 600, 1800, 5400, 16200). They should actually still trigger reasonably frequently, but not overwhelm the event system now. Reason for the decreasing chance is that even at high flammability single building fires should still be more frequent than whole city catastrophic fires.
Flammability Property needs changing in the AI weights, the AI should know that Flammability is not good starting as low as 5, is bad starting at 50 and is really awful starting at 100.
Global Warming event added. This one will need a lot of tweaking. Note: it does alter tiles - but it does not highlight the affected tiles yet, so you may or may not notice anything. This is also a test using the building multiplier, which I have never used before. Chance is 50 times the number of globalwarming buildings a player has. What it does precisely is:
Less precisely: it mostly does what Hydro proposed.
I actually think this mechanic should not be an event at all but go into the DLL at some point, it is actually quite capable of hogging a lot of computation time with high pollution players. I need feedback on whether it is bearable.