TAIPEI: The Central Weather Bureau (CWB) yesterday published a study of weather changes in Taiwan over the past century, showing that local temperatures have risen by an average of 0.8 degrees Celsius.

The average temperature rose by 1.2 degrees in plains areas and 1.4 degrees in metropolitan areas, according to the study, which compiled weather change statistics between 1897 and 2008.

One noteworthy finding was that the minimum temperature increased by 2.1 degrees while the maximum temperature rose by 0.7 degrees on average in metropolitan areas.

"The gap shows that the increase in temperatures at night was greater than in the daytime," a CWB official said.

The survey also found that affected by global warming, Taiwan's isotherms have been pushed northwards by around 150 kilometers.

Isotherms are contour lines that connect or indicate points of equal temperature, usually on maps for special purposes that require such information.

The warming trend also has affected mountain areas, with the average temperature in mountainous areas rising by around 0.6 degrees, while raising the critical altitude for animal habitats by about 100 meters from a century ago.

The CWB also confirmed the general feelings of many local residents: winters are not quite as cold as they used to be and the rest of the year is getting warmer.

Over the past five decades, the number of days with temperature lows falling below 10 degrees Celsius fell by 19 days in mountainous areas but by only one day in low-lying areas.

The number of days with temperatures rising to more than 30 degrees Celsius increased by 28 days in Taiwan proper, though only two days in mountainous areas, and 41 days in its outlying islands.

Though temperatures were up, the amount of sunshine most parts of Taiwan have received has been on the decline, which the CWB attributed to air pollution and suspended particles that blocked the sunshine.

The CWB found that sunny hours on average fell by 176 hours per year in northern Taiwan, 552 hours per year in central Taiwan, 294 hours per year in eastern Taiwan and 417 hours per year in southern Taiwan.

China Daily/CNA

(HK Edition 12/30/2009 page2)