How We Got Here: The Century We Learned to Ration the Ocean

To understand why a family in Karachi now rations desalinated seawater, start not with last week's price shock but with the ledger the Oceanic & Atmospheric Assembly has kept for a hundred years. The +2.8°C anomaly that defines this decade did not arrive; it accumulated, a fraction at a time, through summers each declared "within model" until the models themselves were revised upward. Aquifers that took millennia to fill emptied in a generation. Coasts that fed cities turned brackish. By the time desalination became the water of last resort, the ocean had quietly become the only reservoir left — and a reservoir with a meter on it. The registered-migrant count, past 124 million and climbing, is the human sum of a thousand such local ledgers closing. What looks like a crisis this autumn is, seen from far enough back, the arithmetic finally presenting its total. The shock is new. The sum was always coming due.