Hurricanes moving slowly over an area can cause more damage than faster-moving events, because lingering storms have more time to pound an area with storm winds and drop huge volumes of rain that lead to flooding. Princeton researchers investigated whether global climate change would make these slow-moving storms more common. Using a large ensemble of climate simulations, they found that if future temperatures rose by 4℃ there would be significant decreases in a storm’s forward motion.

Their analysis shows that storms’ forward motion would slow by about 2 miles per hour — about 10 to 20% of the current typical speeds — at latitudes near Japan and New York City. In general, this slow-down wouldn’t affect storms in the tropics.

The researchers found that storms would slow because 4 degrees of warming would cause the westerlies — strong currents blowing through the mid-latitudes — to push toward the poles. That shift is also accompanied by weaker mid-latitude weather perturbations. These changes could particularly slow down storms near populated areas in Asia and on the U.S. eastern seaboard.