New Delhi, Aug. 6 -- On 23 July, the International Court of Justice (ICJ) issued a landmark advisory opinion on climate action that asks all states to act.

It calls upon states to (i) prevent significant harm to the environment, laying out a due diligence standard requiring countries to maintain legal, regulatory, administrative and enforcement measures to achieve rapid and sustained emission reductions.

And (ii) mandatorily cooperate with other countries internationally, which involves acting in good faith through information-sharing, joint efforts to mitigate the effects of climate change and transferring the technology needed to achieve the goals of climate treaties.

Both these duties are under customary law and therefore applicable...