i saw a headline in Prensa Libre yesterday (i read the on-line version of the Guatemalan newspaper), asserting that geologic records show that at the current temperature of the Earth, past sea levels were 8 meters higher than today's sea level. More than 27 feet higher. Bye-bye London (or Ta-ta as the Brits say), along with most major coastal cities.
And the global heating has not stopped, by any means. Atmospheric carbon has not been at this level (now over 400 ppm CO2, swiftly approaching a 50% increase caused by human activities in the geologic eye-blink of less than 400 years) since millions of years ago.
If we stop burning fossil fuels; stop deforestation; transform industrial agriculture; and roll out a humanity-wide practice of agroecology, permaculture, and tree-planting: we may avert catastrophic collapse of the ecology and civilization.
Absent such transformation, it seems the die is cast.