If the current rate were to continue, the world's oceans on average will be at least 2 feet (61 cm) higher by the end of the century compared to today, according to researchers who published in yesterday's Proceedings of the National Academies of Sciences.

Experts say sea level rise is caused by warming of the ocean and melting from glaciers and ice sheets. According to the research, based on 25 years of satellite data, that pace has quickened, mainly due to the melting of massive ice sheets.

The data confirms computer simulations by scientists and accords with the projections of the United Nations, which releases regular climate change reports.

According to lead author Steve Nerem of the University of Colorado, it is a big deal, because the projected sea level rise is a conservative estimate, which is likely to be higher.

''Any flooding concerns that coastal communities have for 2100 may occur over the next few decades,'' Oregon State University coastal flooding expert Katy Serafin said in an email.

Of the 3 inches of sea level rise seen in the past quarter century, around 55 per cent is due to warmer water expanding, and the rest is from melting ice.

The researchers calculated that overall the rate of sea level rise is accelerating by about 0.08 mm per year. If this is not checked, the trend could mean the seas would rise by at least 10 mm per year by the end of the century, which would wreak much havoc on the world's coastal cities.

"This acceleration, driven mainly by accelerated melting in Greenland and Antarctica, has the potential to double the total sea level rise by 2100 as compared to projections that assume a constant rate to more than 60 cm (23.6 in) instead of about 30 (11.8 in)," says Nerem.