Contrails are the ice-crystal clouds jets leave behind. They trap heat in the atmosphere. That heat makes up nearly a third of aviation's total climate impact, according to Dr. Paul Hodgson. This winter, air traffic controllers responsible for the North Atlantic's Shanwick airspace will use AI forecasts to spot exactly where contrails could form, then guide pilots to shift altitude to avoid them. The trial run could be the next step to make a big difference in aviation's impact on the climate.