Two seperate games my early game has been completely wrecked by disasters. The first was an Incan game where I had disasters at 4 because they'd never been a problem before and I kinda enjoyed them. I spawned near 3 volcanoes and had so many eruptions I couldn't get my pop over 4 and constantly had to rebuild my terrace farms. After that experience I dropped the intensity back to 2 and had no trouble for a few games until I started on a large flood plain as Rome on deity. I was penned in by some mountains, Russia and Mongolia so I wasn't able to expand much. 5 cities on a huge map. No big deal, I have legions to take care of that problem right? I had 4 legions built in Rome with an encampment and barracks. I was staging my army in Rome and denounced Genghis to whittle him down before he got his UU. The next turn a 1000 year flood hit and Genghis hit me with a surprise war wiped out half my flood damaged units and took one of my cities. I fought back and recaptured my city plus one of his and had an emergency called on me. Russia swooped in on my other front, Genghis fought back and my short stint as glorious Ceasar wallowed in mediocrity. I still blame that flood although Genghis is a pain on a good day especially with difficulty bonuses added on. It's like everything else, disasters have less impact as the game progresses but the wrong ones in the early game can hurt bad.