Britain has just had the warmest April since records began several hundred years ago (so possibly for some time before that). Following an exceptionally warm (and dry) winter. I don't think there's much doubt that SOMETHING is happening - it's just the cause and implications that people seem to struggle with. It may well be an extension of pre-existing natural cycles, perhaps related to sun activity, perhaps not. I don't see that the cause matters - what DOES matter is that rainfall patterns also seem to be changing, meaning that areas previously arable may become semi-desert and unable to produce food, while other areas that experience greater rainfall won't be able to produce food because we won't have exploited the new rain. Unless we accept what's happening and do something about it, not trying to stop it (futile) but working out how to deal with it, we are headed for a catastrophe.
As a separate question we have POSSIBLY rising sea levels that MAY render vast areas of coastal lands (and many river valleys) uninhabitable. Not too good for Louisiana or eastern Britain and NW Europe, but catastrophic for Bangladesh, the Maldives and many other places. Including AC. Sea levels in at least some areas ARE rising - the Thames barrier east of London which protects the capital from surges up the estuary is already becoming marginal, and there are plans for a second much more extensive one further out which is itself expected to have a limited life. And there is official policy not to protect large areas of eastern England from the inundation which is now accepted as inevitable.
We don't know the cause or the timescale, nor necessarily all the effects. So we don't know if we are looking at changes over several generations or something much more rapid. But pretending nothing is happening is absurd. It seems likely that people already born will see dramatic changes in their lifetimes.