From the Arctic Islands to the Yucatán Peninsula, North Americans are increasingly concerned about the impacts of climate change, and rightly so. They understand the need to act. Their leaders, Prime Minister Justin Trudeau and presidents Enrique Peña Nieto and Barack Obama – the “Three Amigos” – understand it, too. Presenting a joint strategy to address the serious climate challenge was thus of prime importance at last month’s North American Leaders’ Summit in Ottawa… Noted Rutgers University climate scientist Jennifer Francis has in recent years proposed that global warming and the retreat of Arctic sea ice has led to a reduced temperature contrast between the temperate regions and the North Pole. That in turn, she suggests, has changed the character of the Jet Stream, slowing it down and allowing it to wander farther to the north and the south, fuelling climate extremes by allowing weather fronts to stall.