Warming oceans kill phytoplankton that sequester carbon and support other ocean life
So what does this mean? The phytoplankton is an indication of the amount of plant life in the ocean. In fact the phytoplankton is the equivalent of the grass on land. When there is more phytoplankton, the ocean has more food to support the food chain. Furthermore, phytoplankton is essential for enabling the ocean to sequester excess carbon in the atmosphere. The sea is one of nature's "carbon sinks", which removes carbon dioxide from the atmosphere and deposits the carbon in a long-term store - dissolved in the ocean or deposited as organic waste on the seabed. The vast quantities of phytoplankton in the oceans absorb huge amounts of carbon dioxide. When the organisms die they fall to the seabed, carrying their store of carbon with them, where it stays for many thousands of years - thereby helping to counter global warming
Pacific Views, http://www.pacificviews.org/weblog/archives/002353.html. December 9, 2006.