Hurricanes and the Color of the Oceans

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Little kids draw the ocean as blue, but the seas are more complex in color than that. They can be a rich turquoise, like the shallow waters of the Bahamas, or a dark greeny blue, nearly black, out in the middle of the deep oceans. Depth and life, specifically phytoplankton, both influence the ocean's color. It's an issue for more than children's drawings; a new study that will soon be published in Geophysical Research Letters says that ocean color can influence the formation of hurricanes.

Researchers at the National Oceanic and Atmospheric Administration ran simulations of typhoons in the North Pacific and found that bluer water resulted in the formation of fewer storms. Bluer water is water with less phytoplankton and less chlorophyll. It's also water that is more clear, which lets sunlight penetrate deeper, which leaves the surface cooler. In the simulations, when the Pacific gyres—parts of the ocean that rotate in huge circles—had no phytoplankton, storms that formed near the equator dissipated when they moved north over the cooler water. Those storms that did form and persist tended to stay near the equator and hit nearby countries, including the Philippines, Thailand and Vietnam.

Scientists aren't sure what's happening with the ocean's phytoplankton. Some studies have indicated that global phytoplankton has decreased due to climate change over the last century, while others have found a rise in more recent times. But no one is expecting all of the phytoplankton to disappear, like in the simulations. That's a good thing, because no matter the impact of an increase or decrease in these tiny organisms on storms, if we lose phytoplankton, the base of the oceanic food web, we've got even bigger problems.

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