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 on Wednesday. Higher ocean temperatures expand the volume of water, contributing to a rise in sea levels that is submerging small island nations and threatening to great damage 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 of 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（IPCC）, according to the authors.

Rising sea levels are driven by two things: the thermal（热）expansion of sea water, and additional water from melting sources of ice. Both processes are caused by global warming. The ice sheet that sits at the top of Greenland, for example, contains enough water to raise world ocean levels by seven metres（23 feet）, 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 confusing 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 reconcile（与…一致）the models with observed data. Using new techniques to assess ocean temperatures to a depth of 700 metres（2,300 feet）from 1961 to 2003, it shows that thermal warming contributed to a 0.53 millimetre-per-year rise in sea levels rather than the 0.32 mm rise reported by the IPCC.

64. What happens when the ocean's temperature rises?

A. It causes sea levels to rise.

B. It causes sea levels to remain constant.

C. It causes sea levels to decrease.

D. It causes sea level to change.

65. Which of the followings would be buried by the rising sea?

A. Small island nations.

B. All coastal cities around the world.

C. People who enjoy holiday on the beach.

D. Low-lying regions.

66. The new study in this passage _____________.

A. shows that thermal warming contributed to a 0.32 millimeter-per-year rise in sea levels.

B. did not reveal anything that scientists hadn't already known.

C. used new techniques to assess ocean temperatures.

D. shows that models contradict the observed data.

67. What was the main finding of the study?

A. Nothing enough is being done about global warming.

B. That ocean waters have warmed faster than scientists had previously thought.

C. That the warming of the world's oceans is not a threat.

D. A massive report issued last year by IPCC was wrong.