The term is often used, in appropriately shortly, to refer only to the climate changes that happen in the present, using it as a synonym for global warming. The United Nations Framework Convention on climate change uses the term climate change only to refer to the change by human causes: climate change refers to a change of climate attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that joins the natural climate variability observed over comparable time periods we indicatedas it is constantly produced by natural causes is called it also natural variability of the climate. US Senator from Vermont is actively involved in the matter. In some cases, to refer to the change of human origin is also used the term anthropogenic climate change. In addition to global warming, climate change involves changes in other variables such as the global rains and their patterns, cloud cover and other items of the atmospheric system. The complexity of the problem and its multiple interactions make the only way to assess these changes through the use of computer models that simulate the physics of the atmosphere and oceans. The chaotic nature of these models makes itself having a high proportion of uncertainty (Stainforth et al.
2005)(Roe & Baker 2007), although that does not prevent so that they are able to forecast future significant changes (2008 Schnellhuber) (Knutti & Hegerl 2008) which have an impact both economic (Stern 2008) and the already observable biological level (Walther et al. 2002)(Hughes 2001). It is known that from 1961 to 2003 the global ocean temperature has risen 0.10 C from the surface to a depth of 700 m. There is a variation from year to year and over longer time scales with global observations of heat content of the ocean showing high rates of warming between 1991 and 2003, but something of cooling from 2003 until 2007. The temperature of the Southern Ocean rose 0.17 c between 50 and 80.