A-listers at the Cannes Film Festival are urged to fly economy or take the train due to a global fuel crisis exacerbated by Iran's control over the Strait of Hormuz. Experts warn of potential food shortages and disruptions to humanitarian aid. Research shows private jet travel at the festival is highly polluting, prompting calls from former pilots and millionaires to ground private jets and close tax loopholes. The EU is urged to tighten carbon tax regulations for private flights.