Southern Australia and nearby Pacific nations have been warned of a rise in sea levels that could have serious effects. A study at the University of Queensland in Australia has said that since the late 19th century the sea level in the southwest Pacific has jumped about 20 centimetres with the fastest rate occurring in the early decades of the 20th century.
Sea levels around the world rose at an average rate of 1.5 millimetres a year since 1880, but studies of tidal marshes in Tasmania show a rise of 4.2 mm a year between 1900 and 1950, Australian news agency quoted Patrick Moss of University of Queensland as saying.
"Sea levels in Tasmania remained relatively stable for much of the past 6000 years, but around 1880 they started rising drastically," Moss, the co-wrote the study in conjunction with scientists from the UK, New Zealand and Australia, said.
"The rise in 1910 probably reflects the end of the little ice age, when temperatures were about one to two degrees cooler in the northern hemisphere than today," he said adding, "The 1990s peak is most likely indicative of human-induced climate change."
Moss said research suggests the earth has been free of ice at various periods during its existence, at which times sea levels could have been as much as 90-100 metres higher than today.
The findings of the study are published in 'Earth and Planetary Science Letters' journal and indicate the comparatively higher levels in the southwest Pacific are the result of melting ice in the northern hemisphere.
"A large ice-melt is like a fingerprint," Moss said.
"When such a significant mass shifts around the earth's surface we can detect its movement.
"Based on this, it appears likely that the primary source of sea level rise in the southern hemisphere is the Greenland Ice Sheet, but also mountain glaciers in Alaska, western North America and the Canadian Arctic."
Moss's study is largely based on sediment layers in core samples taken from salt marshes near Little Swanport in Tasmania.
Moss said the samples also provided physical evidence of the start of logging in Tasmania, when nuclear testing was at its peak globally and the introduction of unleaded petrol.