Why it Matters: On October 15th, the world reached a deal to amend the Montreal Protocol that could prevent .5°C in temperature rise by 2100. The agreement will cap the use of HFCs – an extremely potent greenhouse gas – by 2019 for developed countries. More than 100 developing countries including China, the world’s top carbon emitter, will start taking action by 2024. The Marshall Islands-led High Ambition Coalition, which played a key role in securing a strong Paris climate agreement, once again led the charge to secure an ambitious amendment and is working on a separate declaration of those countries committed to even faster action. This is essential to keep alive one of the key goals of Paris: to limit warming to 1.5°C.