The wonderful ‘The Song of Phaid the Gambler’ by Mick Farren is set on a future Earth split up into isolated regions by zones of extreme weather, and is looking more like predictive fiction as time goes by.
“The Big Wheel” by William Rollo – a greenhouse gas tipping point is reached and the remnants of humanity are left in space, and Cold War enmities are still in play. Published 1984, New English Library, UK.
Trevor Hoyle’s “The Last Gasp”, 1983, is similar – but the megadoom comes from the death of Phytoplankton in the Earth’s oceans from polution.
Heavy Weather (1994) by Bruce Sterling.
Steven Gould’s “Blind Waves”. That was the first bit of after-the-event climate-change fiction that made me really aware of the possibility of sea-level rise.