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Monday, 25th May 2009

Dragon boats in May, stow the blanket away ?

As the Dragon Boat Festival draws near, we at the Observatory are often asked the question whether the weather has got so warm these days that blankets and winter clothing can be put away earlier.

I have looked at temperature readings around the time of Tuen Ng (Dragon Boat Festival) over the past few decades. Taking a minimum of 25 degrees Celsius as a comfortable temperature for the night, the number of days having this temperature or lower for the 7-day period ending on Tuen Ng is:

10-year period

No. of days with minimum of 25 degrees or lower for the 7-day period ending on Tuen Ng

1979-1988 35 (50%)
1989-199824 (34%)
1999-2008 21 (30%)

It could thus be said that 20 to 30 years ago, nighttime in Hong Kong was comfortable half of the time during the Tuen Ng period. We are losing this fast, and now it has gone down to less than one-third of the time.

Scientific evidence supporting climate change is strong and unequivocal. Hong Kong is hit by a double whammy --- global warming and urbanization, the latter a result of city development and population growth.

The current projection for Hong Kong is that, by the decade 2030-39, the number of cold days, i.e. those with a minimum of 12 degrees Celsius or below, will on average be less than one per year. A more dramatic way of putting this is by that time we will lose winter altogether. Gone will be the days of hot pots and winter fashion.

This is only 20 years from now, and is set to happen earlier if the current way of life and society development does not change.

It takes global effort to contain the warming. The least we Hong Kong people can do is to adopt a simple, less energy-intensive lifestyle.

B.Y. Lee

Last revision date: <17 Jan 2013>