Hong Kong shows signs of flipping from ‘extreme wet’ to ‘extreme dry’ climate, NGO warns
Hong Kong Free Press
Hong Kong’s climate has shown signs of flipping from “extreme wet” to “extreme dry” and is becoming more at risk of drought as a result of climate change, according to a study by an international NGO.
WaterAid, an NGO focused on water, sanitation and hygiene across the world, studied the climatic trends of 112 cities between 1982 and 2023, analysing their “climate hazard” risks and whether they are more prone to flooding or to drought.
Its researchers calculated a “wet/dry index” and categorised each month over the 42-year period into either a wet month or a dry month. When the index passes a certain threshold, that month is considered extreme.
Hong Kong “is not only drying but also experiencing a flip in climate hazards [from extreme wet] to more extreme dry conditions,” WaterAid said in its report, which was published on Wednesday.
The city had experienced more extreme dry months and fewer extreme wet months in the second half of the study period – from 2003 to 2023 – than it did in the first half from 1982 to 2002, the report said.
The NGO ranked Hong Kong as fourth in an index measuring the strength of a flip from wet to dry, behind only Cairo, Madrid, and Riyadh. Taipei ranked ninth.
The report said the flip, as well as the intensification of climate hazards, were due to climate change, which results in a warmer atmosphere and more moisture evaporation. But it did not elaborate on the particular climate conditions that affected Hong Kong.
Instead, researchers suggested that Hong Kong is affected by “completely different climatic conditions” to South and Southeast Asia, where major cities are dominated by wetting trends.
Only 10 out of all 112 cities showed signs of a flip from wet to dry extremes, while 14 displayed a flip from dry to wet.
“Cities long adapted to a wet climate tend to have policies, systems, infrastructure and strategies tailored to managing a surplus of water,” the report said.
“A flip to drier conditions poses new challenges to such cities that may lack the water supply and sanitation systems to deal with more frequent droughts and water deficits,” it continued.
Warmer, drier spring
2024 was Hong Kong’s hottest year since records began 140 years ago, according to the city’s weather service. Last year also saw 35 heat records broken in the city.
The Hong Kong Observatory earlier predicted that this spring will be warmer and drier than usual.
Local researchers have warned that extreme weather events will increase significantly in the next two decades, including hot nights and extreme rainfall.
In September 2023, record-breaking rainfall ground the city to a halt after causing severe flooding and landslides.
The Intergovernmental Panel on Climate Change has warned that the intensity and frequency of heatwaves has continued to increase since the 1950s due to human-caused climate change. The prevalence of greenhouse gasses like carbon dioxide – which trap heat in the atmosphere – raises the planet’s surface temperature, with hotter, longer heatwaves putting lives at risk. Hong Kong has already warmed by 1.7 degrees Celsius since the industrial revolution, research NGO Berkeley Earth says. Heat and humidity may reach lethal levels for protracted periods by the end of the century, according to a 2023 study, making it impossible to stay outdoors in some parts of the world.
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