The top of a mesocosm (experiment water enclosure), tied to buoys for stability, with the Greenpeace ship Esperanza on standby in the background. The ship and crew are working with scientists from the German marine research institute IFM-GEOMAR to investigate ocean acidification, by deploying nine large mesocosms in Kongsfjord, near the Arctic scientific research station of Ny-Alesund. The mesocosms are being used to investigate future implications of ocean acidification, a phenomenon caused by carbon dioxide (CO2) emissions that has just as much potential to damage marine ecosystems as climate change. Absorption of excess CO2 pollution by seawater causes its PH level to drop, making it more difficult for creatures integral to the food web to form shells and skeletons.