This week the Albanese Government reached an historic agreement with the Greens and key crossbench senators on a modified safeguard mechanism to reduce industrial greenhouse gas emissions. So, why has such a nerdy concept featured so prominently in the media and caused such simultaneous and high-pitched rejoicing and angst?

Annual safeguard emissions, currently around 140 million tonnes, had been projected to rise to 146 million tonnes by 2030. Changing this trajectory to 100 million tonnes by 2030 was the signature element of Labor’s climate-change policy at the last election and central to achieving its commitment to 43 per cent emissions reduction from 2005 levels by 2030.