Get used to heatwaves and floods, say Hong Kong Observatory experts

The chilly temperatures that the city experienced last winter are unlikely to ever happen again, while heatwaves and floods from storm surges are expected to become more and more frequent.

Lee Sai-ming, senior scientific officer at the Observatory, said that according to its records the average daily temperature in the city had risen by 1.2 degrees Celsius since 1913.

Lee estimated that as global warming increased, there would likely be only one day per year when the temperature dropped below 12 degrees. On average, temperatures were predicted to rise in Hong Kong by 4 degrees by 2100. "Days where the temperature drops below 4 degrees will not be seen again. Such cold days will now only occur every 163 years," Lee said.

In contrast, days where temperatures reach 35 degrees or above, which used to occur about every 35 years in the last century, now occur every four to five years.

The forum was organised to discuss the findings of the Intergovernmental Panel on Climate Change (IPCC) in its latest report. The IPCC said that data indicating that global warming is the result of the carbon dioxide-producing activities of humans is now 95 per cent confirmed.

An immediate result of continued global warming will be the melting of the polar ice caps, the UN body found, leading to a rise in sea levels. If no effort is made to curb current carbon dioxide emissions, it is likely that before 2050 the Arctic Ocean will be ice-free for at least part of the summer months, the IPCC found.

The findings were shared by Edwin Lai Sau-tak, an assistant director at the Observatory.

"By [2050], we may see passenger cruise tours able to map routes crossing the North Pole," Lai said.

"Global sea levels are projected to rise by between 0.26 metres and 0.82 metres [if carbon emissions are not curbed] by the end of 21st century," he said.

On average, the mean sea level in Victoria Harbour has risen at a rate of 29 millimetres per decade since 1954, according to Observatory records.

"A major impact of the mean sea-level rise is an increase in sea flooding from storm surges caused by tropical cyclones. These extreme sea levels in Victoria Harbour, which now occur about every 50 years, may occur every year by 2100," Lai said.

Last year the Observatory issued 11 cold weather warnings - with the longest cold spell lasting 139 hours, from January 21 to 27. There were 21 days last year when the temperature went below 12 degrees. Nineteen very hot weather warnings were issued last year, with the longest heatwave lasting for 124 hours from July 7 to 12. There were 21 days when the temperature was higher than 33 degrees.