Xiaosong Chen

Every day, the ocean in the tropical Pacific carries on a quiet conversation with itself: water temperatures are slightly higher in some places, slightly lower in others, and these patches of warmth and cold slowly drift into one another. This chatter seems random, but it hides a signal.

The tropics breathe with an annual rhythm: air temperature rises and falls, and within this breath lie two main pulses. The first pulse peaks in February and weakens in August; the second is shifted by half a year. These two pulses are not just background noise for the famous El Niño; they are its conductors.

Every June, the sky over India fills with moisture, and how much falls determines rice harvests, water reserves, and food prices for a billion people. But predicting the monsoon's strength in advance was like guessing someone's mood from a single photo: too many hidden springs.

In the vast concert hall of the atmosphere, ozone plays a part that changes from tier to tier. Near the surface, its notes sound alarming, for there it is a pollutant that irritates lungs and leaves. At 25 kilometers up, the same gas becomes a protective shield that absorbs harsh ultraviolet radiation.

The Tibetan Plateau is a giant sponge that soaks up rain and snow, then releases water to Asia's rivers. Since 2000, the sponge has been getting wetter. Scientists decided to check: does this moisture make the sponge stronger, or does it soften it? They used a measure of disorder — entropy.

The Pacific Ocean breathes slowly and deeply. Every few years, its warm surface waters shift eastward toward the coast of South America, and then Peru gets drenched while Australia goes up in flames. A year or two later, the water retreats, and the picture flips. This breathing is called El Niño, and until now its rhythm could only be guessed a couple of steps ahead.