Piedmont Glacier in north-east Greenland (Coen Hofstede/Alfred Wegener Institute) ============================================================= It should be simple. When temperatures on Earth get hotter, huge amounts of water ice trapped in giant glaciers begin to thaw, releasing water into the oceans, and causing sea levels to rise. It's the story of our lives. By contrast, when global temperatures plummet, which happens during ice ages, sea levels proceed to drop, as water content retreats from the ocean, freezing once more in huge inland ice sheets. This epic, ongoing cycle of ice ebb and flow – the transitions from glacials to interglacials – has been occurring...