Will a coronavirus mirage of clean air, water inspire climate action — or make things worse?

OK, let’s be clear about one thing: Dolphins aren’t actually frolicking in the canals of a deserted Venice, a city on lockdown like the rest of Italy because of the global pandemic. But — as is sometimes the case — those misleading or faked viral tweets are an exaggerated version of something that is true, and also compelling: The shutdown of scores of tourist-packed gondolas has cleaned the murky waters of the ancient city to the point where fish are now visible.

And that’s not the only remarkable vision — practically a mirage, really — as the coronavirus crisis shutters the developed world’s economy to levels that resemble pre-Industrial Revolution society. From Beijing to Los Angeles, formerly slow-moving freeways are suddenly all but deserted at the height of rush hour, and the envelope of smog that once greeted those commuters has disappeared as well. Environmentalists have been posting pollution maps and satellite images of clearing skies that hearken to the 18th century.

Yet no one is really celebrating such a sudden drop in pollution on the eve of the 50th anniversary of the first Earth Day — not when the cause is a global pandemic that has already taken the lives of more than 500 Americans and at least 17,000 worldwide, with efforts to stem the coronavirus bring about an economic shutdown that may already be causing the biggest disruption since the Great Depression.

But on the front lines where scientists and activists have been fighting another planetary threat now abruptly pushed to a back burner — climate change — both the stunning images of blue skies, and gigantic scope of the political and societal interventions to stop coronavirus, raise some inevitable questions. Another world looks possible — but is it all a grand and temporary illusion, to be blurred by a return to normalcy once the all-clear whistle sounds?