The deep blue sea is turning greener. While it may not seem as significant as, say, record-breaking warm sea surface temperatures, the color of the ocean’s surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, microscopic photosynthetic organisms, abound in surface waters and are the foundation of aquatic food webs and the carbon cycle. This shift in water color confirms a trend expected to occur with climate change and signals changes in ecosystems within the global ocean, which covers 70 percent of the Earth’s surface. Researchers led by BB Cael, a senior scientist at the UK's National Oceanography Centre, have revealed that 56 per cent of the global sea surface has undergone significant colour change over the past 20 years. After analysing ocean colour data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite, they found that much of the change is due to the ocean becoming greener. (Keith Cowing)