THE OCEAN'S OWN RANKING

Forty seven years of sea surface temperature, lining up one by one.

Same period and same rules as the air temperature race we published: each bar is one complete year, every month weighted by its length, every cell weighted by the surface it actually covers. A year is born at the bottom of the ranking, grows into its own value, overtakes whoever it can on the way up, and then stops. A year only gets one number and it keeps it forever.

But watch how differently this one behaves. In the air temperature race the ranking churns for two decades before it settles. Here the churning barely happens. The ocean does not hesitate. The order it ends with is almost the order it was heading for from the start, and the warmest years sit stacked at the end of the record with nothing underneath them.

Also watch the numbers, because the interesting thing is how small the spread is. The whole range of this ranking, coldest year to warmest, is well under a degree. Less than on land. That restraint is not good news, it is the physics: water takes an enormous amount of energy to warm up, and the ocean has absorbed around ninety per cent of the extra heat trapped by greenhouse gases. Every tenth of a degree you see here cost a staggering amount of energy to produce.

The land warms faster and makes the headlines. The ocean warms slowly and sets the terms: it is what holds the heat, moves it around the planet, feeds the storms, and decides how much sea level rises. A slow bar is not a reassuring bar.

Two things stated on screen, as always. The axis does not start at zero, because the ocean surface averages around 19 degrees and moves by about one degree across the record. And the polar bands above 60 degrees are excluded: ice covered cells are filled with the freezing point of seawater, so the loss of ice would register as warming without being a measurement of anything.

Data: NOAA ERSSTv5, 1979 to 2025. Monthly SST, area weighted, 60S to 60N.