Decades-long swings in the temperature of the North Atlantic Ocean are known to influence everything from surges in hurricane activity to drought in the African Sahel. Scientists have attributed those temperature swings to natural oscillations in the strength of the ocean currents that bring warmth from the south. But a group of climate scientists argues today in Nature that the waxing and waning of atmospheric hazes—tiny particles belched by everything from smokestacks to volcanoes—over the North Atlantic drove ocean temperature changes there. Hazes (seen over the U.S. mid-Atlantic, above) work by varying the amount of sunlight they block from the ocean surface. Older climate models can't duplicate the effect, the group says, but a new-generation model can. If hazes do in fact drive most North Atlantic temperature swings, long-range climate forecasters would have to get into the far hazier business of predicting volcanic eruptions and pollution trends.
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