I believe the worst event is the lack of action on carbon emissions. Coasts and island will be inundated, temperatures will be unbearable in many places, and lack of water and food will be driving desperate people from afflicted regions.
Second I would say is the rise of anti-democratic ethnic nationalism and fascism. Putin’s Russian expansionism and ties to the Orthodox Church would be an example. Another is Trump’s support among evangelicals, neo-Nazis, and other “patriots” who can be whipped into a hateful frenzy by the mere existence of people outside the straight, white, “Christian” norm.