World Ocean Census - Extract 12 - Disappearing Ice oceans
24 February 2010
Dramatic change is occurring at the opposite poles of our planet. A climatic shift caused by global warming is leaving an indelible mark on the “ice oceans” and the creatures that inhabit them. The ice at the poles has always grown and shrunk with the seasons. However, as global average temperatures rise, the overall amount of ice at the poles is shrinking. Each year during the month of September, the amount of sea ice floating in the Arctic Ocean is typically at its lowest for that year. In 2007, however, the loss of Arctic sea ice in September set a modern-day record: the ice cover shrank to about 4.1 million square kilometers (1.6 million square miles) – 43 percent less than in 1979, when accurate satellite observations first began.
Similarly, the Antarctic ice sheet, which covers about 98 percent of the continent and has an average thickness of more than 1,600 meters (1 mile), is losing approximately 150 cubic kilometers (36 cubic miles) of ice every year, according to a recent study that used satellite observations.
Scientist aboard RV Polarstern captured this picture of a drifting plateau iceberg in a very calm sea in Antarctica. The iceberg was one of the thousands seen by researchers during a 10-week expedition to the Wedell Sea in 2006-07. Courtesy of G. Chappelle/ AWI
Because of these dramatic, relatively rapid changes, there is a sense of urgency among scientists studying life in the ice oceans to learn as much as they can, as quickly as they can, before the regions are irreversibly changed. Fortunately, a means of studying these regions more fully was already in the works with the designation of the fourth International Polar Year (IPY) by the International Council for Science and the World Meteorological Organization (the previous IPYs were in 1882–83, 1932–1933 and 1957–58). To allow for full and equal coverage of both the Arctic and the Antarctic, the fourth IPY (actually two years – from March 2007 to March 2009) brought together thousands of scientists from more than 60 nations to examine a wide range of physical, biological and social research topics. Two Census projects are playing an integral role in the IPY initiative; in the Antarctic region alone, the Census has gathered data from 18 expeditions during this two-year period.
Scientists are racing to study these areas before they are further affected by climate change so that they can establish a baseline against which future changes can be measured. Researchers are also seizing the opportunity to discover what inhabits these regions before they are altered by climatically induced environmental changes.
Since the polar regions have been underexplored because of their relative inaccessibility, the rate of discovery when these areas are sampled has been simply remarkable. New life-forms have been found on virtually every expedition to these remote regions. It is estimated that half of all species found below 3,000 meters (about 2 miles) in the global ocean are new to science; in isolated parts of the world, such as the Southern Ocean, the figure may be closer to 95 percent. In three expeditions to the Southern Ocean from 2004 to 2007, for example, more than 700 new species were discovered.
Text and images reprinted with permission from World Ocean Census: A Global Survey of Marine Life by Darlene Trew Crist, Gail Scowcroft and James M. Harding Jr., Firefly Books, 2009