Saturday 7 February 2015

Climate Sceptic Wyss Yim

Good letter from Professor Johnny Chan ... putting Professor Wyss Yim in his place

Global warming sceptics must stop cherry-picking data

PUBLISHED : Wednesday, 04 February, 2015, 5:04pm

Professor Wyss Yim's letter published on January 29 ("Hottest year? Not in Hong Kong") argued that urbanisation is the culprit of all the warming that is observed, and that the global temperature actually decreased during the period from 1998 to 2014.

This is typical of climate sceptics who often cherry-pick data to argue that the globe is not warming.
If urbanisation were the only reason for the observed warming, why has the Arctic sea ice shrunk by about a third since 1980? Why have significant amounts of ice melted in many of the glaciers? Why has the ocean temperature continued to increase? In these places, very few people live, and surely no urbanisation exists.

Yes, urbanisation enhances warming in the cities but the increase in temperature is global and not confined to the cities. According to the World Meteorological Organisation, the weather authority within the United Nations, the average temperature over land and ocean in 2014 was 0.57 degrees Celsius above the 1961-1990 average.

Note that the average over land includes all temperature records and not only those in the cities. Just because the temperature in Hong Kong is not the hottest does not imply global warming is not occurring!

As to the "pause" in the warming, the climate system is very complex and the global temperature will always be affected by many factors that occur on relatively short time scales.

Yes, there was short-term downward trend in temperature during the period from 1998 to 2013, but this also happened in the 1970s. And, yet, after the brief downturn, the temperature rose again.
What we are talking about here is a long-term trend and not a short-term one. While there might be periods during which the global temperature decreases, it is still increasing if you examine the record for a longer period of time.

I think the climate sceptics should not cherry-pick data to argue that human-induced global warming is not occurring. There is overwhelming evidence that their argument is invalid.

If we continue to say that human activity has nothing to do with the observed increase in temperature, and therefore nothing needs to be done to reduce our greenhouse emissions, our earth as we know it will be doomed.

Of course, most of us reading this letter will be dead by the time this happens, but is it fair to do this to our future generations?

Johnny Chan, dean and chair professor of atmospheric science, City University of Hong Kong

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