Climate change and extreme precipitation: Is there a connection?
Although an individual extreme precipitation event cannot be solely attributed to climate change, as pointed out in scientific studies, climate change will likely affect the frequency of occurrence of such events in the long term. It is because the tropospheric warming due to increased anthropogenic (human induced) greenhouse gases can lead to an increase in the water-holding capacity of the atmosphere. The warming may also enhance the hydrological cycle and atmospheric instability. A less stable atmosphere with more water vapour in the air will provide a more favourable condition for intense precipitation events.
Moreover, some studies suggest that urbanization effect may also partly contribute to heavier rain in urban areas. This may be attributed to the urban heat island effect that enhances the convective activities, the increased roughness over a city that slows down the storm movement and the increase in the concentration of suspended particulates from urban activities that helps the formation and development of rain-bearing clouds.
Locally in Hong Kong, a study on the past occurrences of extreme rainfall indicates that heavy rain events in Hong Kong have become more frequent in the last 120 years or so.
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Note : Precipitation is the general term for rainfall, snowfall and other forms of frozen or liquid water falling from clouds.