A century or two from now, people may look back at our current era — with its record-breaking high temperatures year after year, rapid disappearance of Arctic sea ice, and gradually rising sea levels — as part of a much cooler and far more desirable past. The spate of extreme weather events in the past month — which have devastated America’s fourth-largest city, Houston; spawned a massive hurricane that tore through the Caribbean and Florida; and swamped large swaths of India and Bangladesh — may well be a prelude to more monster hurricanes, Biblical rain events, and coastal inundations brought about by extreme weather and vastly higher sea levels.