As the coronavirus tears around the world, it is exploiting our biggest weaknesses, from under-resourced health care systems to rampant social inequality. Its relationship with one pervasive and neglected problem, however, is more tangled: Air pollution has intensified the pandemic, but the lockdowns imposed in its wake around the world have-temporarily-cleaned the skies. It meant that on this year's Earth Day, that fell on April 22nd, people in some parts of the Indian subcontinent were able to see the mighty Himalayas from where they live for the first time, thanks to reduced air pollution.

From China's Hubei province to industrial northern Italy and beyond, pollution levels have plummeted as lockdowns aimed at slowing the viral spread have shuttered businesses and trapped billions of people at home. Even residents of the Bangladesh capital, Dhaka, have experienced cleaner air in recent weeks, although this has tended to be intermittent. The city that consistently ranks in the top 5 of AirVisual's real-time Air Quality Index for pollution levels in cities around the world, has seen itself drop out of the top 20 on a number of days over the past 4 weeks. Used to scoring in excess of 200 (a score of between 201 and 300 is classified as "very unhealthy", while between 301-500 is classified as "hazardous") on most days, Dhaka's residents will have been pleasantly enthused at seeing their city's air registering scores under 100 (e.g. April 11 and 15) on the index during the lockdown. And yes, they will have noted the supreme irony, in being unable to go out and breathe it all in.

Not to suggest it might be worth the price of a pandemic, but researchers at the University of California, Santa Barbara are projecting carbon emissions could fall 4% in 2020-a historic decline in a single year. Yet even this would not come close to achieving some of the aims identified in the Paris Climate Accord. Global emissions would need to fall by some 7.6% every year this decade in order to limit warming to less than 1.5C above pre-industrial temperatures, one of the principal aims.

In any case, the declines are sure to be only temporary. We know that to get healthier air for the longer term means shifting to clean energy and transportation, not ordering people to stay at home at drastic economic cost. But the cleaner pandemic skies do show how fast we can bring down pollution when we reduce our burning of fossil fuels. It has shown us Mother Nature's remarkable ability to heal herself so quickly, if only we refrain from plundering her resources a bit, coupled with climate action can yield tangible, visible results. Once the pandemic is over, this glimpse of the cleaner, greener world that is indeed possible may just occasion us to want it back again, only this time with a permanence. On the occasion of the 50th anniversary of Earth Day, here's to hoping.