A hurricane is a giant vortex of wind that forms over warm ocean water. It needs energy, just as a fire needs fuel. A hurricane draws its energy from temperature differences: the warmer the water and the cooler the air above, the more powerful the storm can become.

Previously, scientists assumed that as the planet warms, hurricanes should intensify across all oceans simultaneously. But when they examined each ocean separately, they found otherwise. In the North Atlantic, the number of the most intense hurricanes increased by 7.5 per decade. In contrast, across three parts of the Pacific Ocean, no such increase was observed: in one region the relationship was actually reversed, and in the other two there was none.

This is similar to a situation where one city sees more fires due to heat, while a neighboring city does not, even though the heat is the same everywhere. The reason must lie not only in the heat but also in local conditions: how much dust is in the air, how the winds blow, and how the water circulates. Therefore, hurricane forecasts need to be made for each ocean individually, not for the whole planet at once.