People just say "Wow, climate change is worse than we thought" and move on with their lives.A bit of going on a dead thread here, but.
I don’t know if anyone has said it but the Percy Jackson books give us a sudden eruption of Mt Saint Helens around June 20 2008 (the timeline I found places it between the 13th and the 24th), whose strength isn’t specified but causes at least half a million people to be evacuated, and after that the volcano erupts a few more times (or the eruption doesn’t stop) until some point around June or early-August when the volcano is obliterated in a single new eruption when Typhon escapes it.
Which, after that, sees Typhon cross the US as a ‘freak storm’ (cof-tornado/hurricane-coff) that ends only in August 17th at which point it had reached Manhattan (and with Brooklyn bridge being destroyed) while storm spirits still continue to cause havoc until at least a few months later (meaning more freaky but less destructive storms)
I’m not going to enter on the other books and series but this alone would probably have some major effects on the world
At most there will be a state funeral for those killed by the storms. Perhaps some Islamist leader, like Bin Laden, shouts that this is "a punishment from Allah against the United States for his acts against Islam" (surely this leader will be ignored by anyone who is not an Islamist).
Other than that, surely global warming activists will gain more traction "ahead of time" now that they can exploit this disaster as evidence that their claims are true (Never mind this disaster isn't consequence of climate change, already it still seems like exactly what they're warning against as "sure outcome of climate change").
But removing that I don't think there will be too many changes: as far as people know, none of this has changed their conception of the world as they understand it.