Bangladesh already suffers catastrophic floods and is already being exacerbated by human influences: https://en.wikipedia.org/wiki/Floods_in_Bangladesh#Coverage_...

Small changes that we'll see well before the end of this century will have huge consequences. Don't be surprised if the country doesn't exist at all by the end of the century.

Oh good, so we have time?

Not sure what you're point is unless to say that this problem is on a long enough time horizon (where the survival rate for everyone drops to zero ...).