Time is almost out to avoid a climate catastrophe that would leave today’s children and future generations with a world starkly different from the one that nurtured civilization for the past 10,000 years, according to one of the world’s most eminent climate scientists.

Left unchecked, for example, rising global temperatures could soon cross thresholds that melt enough ice in Greenland and Antarctica to drown all of the world’s existing coastal cities in rising seas.