Over a time lapse of only about 170 years, the trajectory of greenhouse gas (GHG) in the atmosphere has exceeded the 1.5°C security level established in the Paris Agreement. States and international organisations have thus far addressed global warming primarily by means of policy-making and law-making–that is, from the standpoint of ‘primary’ rules, but convergence is still limited. Climate science indeed warns that the timely achievement of carbon neutrality by 2050 currently necessitates drastic cuts in GHG emissions on a yearly basis. Can therefore a progressive implementation of ‘secondary’ norms, that is, sanctions and ensuing enforcement procedures, meaningfully contribute to fostering a fast transition to a low-carbon economy based on renewables and, possibly, nuclear energy and further innovative technologies, including corresponding adaptation measures? ‘Hard’ and ‘soft’ mechanisms, both ‘public’ and ‘private’ in nature, whereby enforceable sanctions integrate goal setting, pledges and a variety of behavioural incentives, disclose a fragmented ‘enforcement deficit’, which compels case-by-case decentralised solutions, whereby the threshold is by now set at a 2°C temperature increase above pre-industrial levels, with fast-approaching tipping points.