New York (VNA) - Sea level has risen by 3 cm a year on average over the past 12 years, while the average rise in sea level over the past 50 years is 0.18 cm only, NASA scientists said.

Although the rise in sea level has been controlled since the early 20th century, it is impossible for scientists to know how much the sea level has risen over the last 100 years.

With assistance from the most advanced equipment and satellites, NASA scientists now can determine exactly the change of sea level and the reason for its rise.

The current rise in global sea levels is the consequence of some factors, of which global warming is the most important. The process melts the ice caps, which cover a great proportion of the earth’s surface and contain three - fourth of fresh water in the world, leading to a rise in sea level, maybe up to 67 metres higher.

If the sea level rises by just 1 metre, more than 100 million people will be affected, NASA scientists said.