Sea levels to rise for next 1,000 years, says UN report

UN:World sea levels will keep rising for more than 1,000 years even if governments manage to slow a projected surge in temperatures - blamed on greenhouse gases - this century, a draft United Nations climate report says.

The study, by a panel of 2,500 scientists who advise the UN, also says that dust from volcanic eruptions and air pollution seems to have braked warming in recent decades by reflecting sunlight back into space.

The Intergovernmental Panel on Climate Change (IPCC) will publish its report, the most complete overview of climate change science, in Paris on February 2nd after a final review. It will guide policymakers combating global warming.

The draft report projects more droughts, rains, shrinking Arctic ice and glaciers, and rising sea levels to 2100. It also cautions that the effects of a build-up of greenhouse gases in the atmosphere will last far longer.

"Twenty-first century anthropogenic [ human-caused] carbon dioxide emissions will contribute to warming and sea level rise for more than a millennium, due to the timescales required for removal of this gas," scientific sources quoted the report as saying.

Still, the report has good news. It quoted six models with projections of sea level rises this century of between 28cm and 43cm (11in and 16.9in). This compared to a far wider band of 9cm to 88cm (3.5in to 34.6in) in a 2001 report.

Sea levels rose by 17cm (6.7in) in the 20th century. Rising seas would threaten low-lying Pacific islands, coasts from Bangladesh to Florida, and cities from Shanghai to Buenos Aires.

The report says it is "very likely" - or more than a 90 percent chance - that human activities, led by the burning of fossil fuels, are to blame for warming since 1950. The previous report in 2001 said the link was "likely", or at least 66 per cent. Lingering uncertainties include whether higher temperatures will bring more clouds - their white tops bounce heat back into space.

In New Delhi, IPCC chairman Rajendra Pachauri said: "I hope this report will shock people, governments into taking more serious action as you really can't get a more authentic and a more credible piece of scientific work."

The draft report projects temperatures will rise by 2° to 4.5°Celsius above pre-industrial levels with a "best estimate" of a 3° rise, assuming carbon dioxide levels are stabilised at about 45 per cent above current levels.

That is a narrower range than the 1.4°-5.8° projected in the previous IPCC report in 2001, which did not say what end of the band was most likely. The EU says any temperature rise above 2° will cause "dangerous" changes.

Stabilising carbon dioxide levels would lead to a further temperature rise of about 0.5°, mostly between 2100 and 2200, and push up sea levels by a further 30cm to 80cm (11in to 31in) by 2300 with decreasing rates in later centuries, it said.

It notes that sea levels were probably 4-6m (13-19½ft) higher when temperatures were 3° higher than the present in a period between ice ages 125,000 years ago.

The Gulf Stream, bringing warm waters to the north Atlantic and keeping Ireland temperate, was likely to slow but not enough to offset an overall warming. And there was scant chance of an abrupt shutdown of the ocean current system by 2100.