The World's oceans have warmed 50 per cent faster over the last 40 years than previously thought due to climate change,Australian and US climate researchers have reported Higher ocean temperatures expand the volume of water, contributing to a rise in sea levels that is submerging small island nations and threatening to wreak havoc in low-lying, densely-populated delta regions around the globe. The study, published in the British journal Nature, adds to a growing scientific chorus of warnings about the pace and consequences rising oceans. It also serves as a corrective to a massive report issued in the year 2008 by the Nobel-winning UN Intergovernmental Panel on Climate Change, according to the authors. Rising sea levels are driven by two things, the thermal expansion of sea water, and additional water from melting sources 9!" ice. Both processes are caused by global warming. The ice sheet that sits atop Greenland, for example, contains enough water to raise world ocean levels by seven metres, which would bury sea-level cities from Dhaka to Shanghai. Trying to figure out how much each of these factors contributes to rising sea lev