Polar storms in the northernmost Atlantic region, which are too small or short-lived to be resolved by most climate models, significantly affect the overturning circulation of the North Atlantic Ocean, according to research published online in Nature Geoscience. Because the frequency of these storms is expected to decline as the planet warms, ocean circulation may weaken more than projected by the current climate models.

Alan Condron and Ian Renfrew compared ocean-sea-ice model simulations that included the effects of polar storms on the ocean circulation with model runs without these effects. They show that more water is transported along the main circulation pathways of the North Atlantic when the effects of the polar storms are taken into account. They conclude that the impact of the thousands of polar low-pressure systems that traverse the northern parts of the North Atlantic Ocean each year need to be considered in climate-prediction models.