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Tuesday, 16th June 2009

Climate change - the latest warning

The past year, 2008, saw a number of weather records broken in Hong Kong.

First, it would be best remembered as a year with the longest cold spell in 40 years, which lasted 24 days from late January to mid-February.

Apart from this, several rainfall records were also broken. The deluges in June 2008 brought 1346.1 mm of rain, making it the wettest month since record began in 1884, while the hourly rainfall of 145.5 mm on 7 June broke all past records by a wide margin (Note: the last record was 115.1 mm, recorded on 16 July 2006). The 237.4 mm on the day of 19 April was an all-time daily high for April, while the hourly rainfall of 46.6 mm in the morning of 3 November was the highest for the month of November.

Temperature-wise, October 2008 with a mean of 26.5 degrees was the warmest October ever.

All these are telling us one thing --- we are facing more weather extremes. Scientifically, it is not possible to blame them 100% on climate change. However, newspapers are telling us that many places in the world are experiencing more weather extremes than ever. Climate scientists have long indicated that practically everywhere in the globe, more and more extremes are on the way.

The Intergovernmental Panel on Climate Change (IPCC), which received the Nobel Peace Price in 2007 for its work on climate change, concluded that climate warming is unequivocal. For Hong Kong, six of the ten warmest years on record occurred in the past ten years.

Results of international research work published this year raise the alarm further. Climate modelling work has been carried out by scientists from U.K. Meteorological Office to find out what would happen if all emissions of carbon dioxide, the major greenhouse gas contributing to global warming, stop immediately. That is, we instantly cease all fossil-based power generation, transportation, industry and manufacturing.

The study finds that even so, the carbon dioxide level in the air would remain high for the next 100 years because nature can only take up a fraction of it. The effect of this is that global temperatures would stay up. That is, there would not be any appreciable cooling. Worse, if all emissions stop 40 years from now, i.e. 2050, temperatures would continue to rise further for at least a century.

CO2 ConcentrationTemperature increase above pre-industrial level

(Simplified from an article in Nature, Vol. 458, p.1093, April 2009.)

A similar study conducted by scientist from U.S. National Oceanic and Atmospheric Administration gives the same result, except that the picture looks even worse --- carbon dioxide levels would remain elevated 1 000 years into the future. Welcome to very warm, sizzling world.

So, is it time to act ?

B.Y. Lee

Last revision date: <17 Jan 2013>