The world's oceans have warmed 50 percent faster over the last 4

The world's oceans have warmed 50 percent faster over the last 40 years than previously thought due to climate change,Australian and US climate researchers reported Wednesday．Higher ocean temperatures expand the volume of water,contributing to a rise in sea levels that is covering small island nations and threatening to destroy the low-lying,densely-populated low 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 last year by the Nobel-winning UN Intergovernmental Panel on Climate Change(IPC C),according to the authors. Rising sea levels are driven by two things:the thermal expansion of sea water,and additional water from melting sources of 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 meters,which would bury sea-level cities from Dhaka to Shanghai. Trying to figure out how much each of these factors contributes to rising sea levels is critically important to understanding climate change,and forecasting future temperature rises,scientists say．But up to now,there has been a puzzling gap between the projections of computer-based climate models,and the observations of scientists gathering data from the oceans. The new study,led by Catia Domingues of the Centre for Australian Weather and Climate Research,is the first to reunite the models with observed data．Using new techniques to assess ocean temperatures to a depth of 700 meters from 1961 to 2003,it shows that thermal warming contributed to a 0.53 millimeter-per-year rise in sea levels rather than the 0.32 mm rise reported by the IPC C. What happens when the ocean's temperature rises?
A、It causes sea levels to ris
B、It causes sea levels to decreas
C、It causes sea levels to remain unchange
D、It causes sea flood all over the glob
【正确答案】：A
【题目解析】：在文章中提到，随着海洋温度的升高，海水的体积会扩大，这会导致海平面的上升。文章还明确指出，这种海平面的上升正在淹没小岛屿国家，并威胁着全球低洼、人口稠密的低地地区。因此，当海洋温度上升时，最直接和显著的影响是海平面的上升。 对于选项： A. 它导致海平面上升 - 这与文章中的描述相符，是正确答案。 B. 它导致海平面下降 - 这与文章中的描述相反。 C. 它导致海平面保持不变 - 文章中没有提及这种情况。 D. 它导致全球洪水 - 文章没有提到海洋温度的上升会直接导致全球洪水，而是提到了海平面上升对特定地区（如小岛屿国家和低洼地区）的威胁。 因此，正确答案是A。