Phytoplankton may affect global weather by seeding clouds

BBC : Clouds, which are made of water drops or ice crystals in the atmosphere, play an important role in Earth’s weather. Ice crystals form when particulates in the air trigger water droplets to freeze. Now researchers have found that some of those airborne ice-nucleating particles come from phytoplankton secretions in the ocean that are lifted into the atmosphere by wave action and sea spray. Theo Wilson of the University of Leeds in the UK and colleagues used a remote-controlled boat to gather samples from the very top layer of water in the Arctic, northwestern Atlantic, and northeastern Pacific Oceans. They found that the phytoplankton’s tiny gel-like secretions, which are just 0.2 μm in size, are small enough to be wafted into the air where they act as the nucleus for the formation of ice crystals. The researchers say that such marine organic material may be a significant factor in cloud seeding, particularly in remote marine environments, and must be taken into account in future climate models.