Interesting perspective: that nationalism doesn't object to climate action per se, rather it objects to collective climate action.

In a perverse way, nationalism may be the solution to climate change. Countries that decide "We can't trust the others. We'll need our own energy / agriculture / manufacturing / supply chains..." can best achieve those ends with renewable solutions. Local renewable energy, cellular agriculture, ramped up production of clean technologies. Most importantly, nationalism will drive competition, meaning the first countries to achieve self-sufficiency will also the be the first to export excess (ala China).

All of which could potentially solve climate change in ways cooperation could not.