Reimagining the world after Covid

(CNN)The way we got here -- a Covid-19 contagion that has sickened more than six million people and killed nearly 380,000 globally -- is absolutely horrible, but the pandemic has awakened the world to at least one thing that's positive: Clean air and healthy cities are a blessing. The air in Delhi was clean enough under a lockdown in late March that residents finally could see the blue sky. The famous smog in Los Angeles lifted. Where I live, in Salt Lake City, Utah, the air was clear enough that I could see all the way across a typically gray and polluted valley. Honking horns and smoke-belching trucks were replaced with the songs of birds. "I have not seen such blue skies in Delhi for the...