CUSP briefing addressing the question of when the UK should aim for zero carbon emissions. In it, Prof Tim Jackson is making the case for a (fair) zero carbon target of 2030, calling for a policy strategy not only on zero carbon targets, but emission pathways, with a defined level of negative emission technologies. It is notable that reduction rates high enough both to lead to zero carbon (on a consumption basis) by 2050 and to remain within the carbon budget require absolute reductions of more than 95% of carbon emissions as early as 2030.