A recent paper estimates that vertical wind shear over the North Atlantic has increased 15 percent during the last four decades - but it is hard to know how much because it's only since the 1980s that we've had accurate measurements, even of things like temperatures.

Models say climate change will lead to an increase in clear-air turbulence, invisible to both pilots and weather radar, and planes will be fine structurally but if you are moving about the cabin when it happens, you will get knocked around.

Which means government is likely to tell you that you can't move around the cabin without getting individual permission from a flight attendant. An already third-world American travel experience is only going to get worse if you can't even stretch your legs.