I think they nastiness of the Greenhouse Effect is much under-advertised. Hot, damp, decay smells. Forest-fire stenches the plume of smoke from Mexico in 1988 reached as far north as Chicago. Lawns drowning and rotting. Things remaining soggy for long periods, in areas where things have never been soggy before.
Animals show up where they've never been seen before, sometimes in big, buggy, biological booms.
Birds and amphibians vanish. Bridges and roads wash out. Lots of urban power failures in the summer, because even if the power keeps coming, the heat burns the wiring out. But mostly, bad smells. Smoky, moldy, gooey, weird smells that you never quite smelled before an evil, creepy stink is the very signature of the Greenhouse Effect.