The growing dangers of record heat waves like the one engulfing July 4th celebrations

Americans across the East Coast are preparing for one of the hottest Independence Days in recorded history.

Triple-digit temperatures have disrupted travel, strained the energy grid and forced some communities to change or cancel planned celebrations.

Meanwhile, health authorities in Europe have now linked thousands of excess deaths to record heat.

Jeff Goodell joins Amna Nawaz to unpack it all. ...