Food waste is a climate issue, representing 8-10% of global greenhouse gas emissions. The UK has a long-standing reputation as an international leader on food waste action: now it is time to realise the potential of ambitious food waste prevention to deliver climate goals. This policy brief sets out the overwhelming case for scaled up, regulation-led action on food waste, as part of an ambitious plan to decarbonise the UK’s food system. The brief explores, first, why solving the climate crisis requires action on food waste; second, why action to date is failing to truly realise the emissions saving potential of food waste prevention; and third, what an effective food waste prevention policy would look like.