Humans are changing the atmosphere beyond recognition.

Ever laid under a tree on a warm summer’s day and watched the clouds drifting by? Or marveled at the stars at night? The skies above us and the air we breathe are as familiar to us as they were to our ancestors thousands of years ago.

But what we’re doing to the atmosphere these days is completely new.

The key message here is: Humans are changing the atmosphere beyond recognition.

As you may have guessed, we’re talking about pollution. It’s not that our releasing noxious substances into the air is anything unusual. Just think of the infamous London smog. However, the extent of the damage has changed dramatically.

Humans are no longer just a tiny puff of smoke on the vast surface of the earth. Today, we’re altering the atmosphere on a global scale.

This is partly because there are so many more of us now; the world’s population is already more than seven billion. But that’s not the only reason. The days of the “dark Satanic mills” of the Industrial Revolution may be long gone. Stricter pollution controls have cleared up the visible soot and sulfurous gasses that used to dirty the skies. What they haven’t got rid of is the source of the problem itself – coal power. Pollution from coal power stations in Europe alone still kills more than 22,000 people a year.

And the developing world is also contributing more pollution than ever. In China, there’s so much dirty industry that only a tiny 1 percent of the population is breathing air that European Union standards count as clean.

What’s more, people are adding their own homemade pollution to the industrial emissions.

In Nepal, for example, the largest polluter is the wood and dung cooking fires used all over the country. They arguably make for the tastiest chapatis, the popular local flatbread. But what they also do is infuse the air with a distinctive acrid brown haze.

The effects of the haze are many, from rising temperatures to frequent droughts, which result in failed harvests. And the health effects are as alarming as the environmental ones. In India alone, estimates say that, annually, almost two million people die from conditions related to the haze – more people than are killed by malaria worldwide.

The good news is that the effects need not be permanent. If all the emissions were to stop at once, it wouldn’t take many years for the atmosphere to recover.

But we all know that’s not about to happen. So the challenge for humanity is going to be to learn to live in this new atmosphere and the new climate it brings.