New Delhi, Feb. 12 -- As Donald Trump begins his second term as US president, the world is bracing for a dramatic shift in US climate policy. His first presidency was marked by a withdrawal from the Paris Agreement, a regulatory rollback on emissions and a strong embrace of fossil fuels. His successor Joe Biden rejoined the commitment made in Paris, where leaders of nations had come together in 2015 to "pursue efforts" to contain global warming, key among them being to set up country-level emission-reduction targets.

Now, with Trump back in the White House, early indications suggest an even more aggressive dismantling of climate priorities. One of his first actions was to exit the Paris deal, which according to the rules will take a year...