(12 September 2023 SCMP)
Within two hours on Thursday night, the Hong Kong Observatory had exhausted the rainstorm warnings it could issue: amber, red and black. The observatory attributed the heavy downpours around the city to the trough of low pressure associated with Typhoon Haikui, although that storm, unlike Typhoon Saola, had not made landfall on Hong Kong.
A black rainstorm warning is issued by the Hong Kong Observatory when rain exceeding 70mm an hour has fallen or is expected to fall. In this instance, the city experienced 158.1mm of rain in an hour, more than double the warning threshold.
Last week’s black rainstorm rewrote more than one record since records began in 1884. It broke the previous hourly rainfall record of 145.5mm set in 2008. The black rainstorm signal was hoisted for more than 16 hours, also exceeding the previous record of nearly six hours in 1999.
Between Thursday night and Friday morning, images and videos of flash floods in MTR stations, roads and shopping malls were also uploaded by members of the public and spread widely on social media.
Those scary scenes unfolding in Hong Kong reminded me of the film An Inconvenient Truth, which I watched when it came out in 2006. At that time, the film was already describing the dire consequences inflicted by climate change.
I am guessing many ordinary people, as well as business leaders and government officials, also watched the film. However, I wonder how many of them have since acted on it, adjusting their lifestyles or implementing measures to make the planet less prone to climate change disaster.
Whether one believes in climate change or not, humankind should take the necessary steps to lower the impact of extreme weather events and make our habitat truly climate-resilient to minimise loss and damage.
For example, the city’s drainage systems were designed to withstand up to once-in-200-years rainstorms and floods. Last week, the systems were stretched by the torrential downpours that exceeded 600mm in 24 hours, which amounted to a quarter of the city’s average annual rainfall.
Over the years, the authorities have made improvements to aged drainage systems and constructed underground stormwater storage tanks to prevent flooding. However, the disruption brought by the latest storm shows there is certainly room for more improvement, especially in anticipation of more intense rainstorms and rising sea levels in the future.
The authorities should also consider using a network of nature-based solutions to effectively retain stormwater in urban environments. As the Drainage Services Department has explained, due to rapid urbanisation in the 1980s, large areas of natural ground became paved areas. As a result, there is less natural ground to retain rainwater, which becomes surface flow that then needs to be diverted into the sea through non-natural drainage systems.
In Hong Kong, listed companies are required to publish annual sustainability or ESG (environmental, sustainability and governance) reports, to inform investors of steps they have taken towards climate adaptation and resilience. Such disclosures are important in giving investors confidence that businesses can be operated amid climate change or any other types of threats.
Although the Hong Kong administration is not a listed company per se, Chief Executive John Lee Ka-chiu should require all government departments to make public their strategies and action plans for making the city climate-resilient in light of foreseeable extreme weather events such as floods and heatwaves.
By requiring disclosures across government departments, the authorities would be able to review any weaknesses and deal with them, so as to keep the city running smoothly whatever the rainstorm warning level.
Amid serious flooding, landslides and water supply disruption, parts of the city became dysfunctional, demonstrating the vulnerability of humankind in the face of the power of nature. More than ever, we should be developing our economy in harmony with nature.
Edwin Lau
Executive Director, The Green Earth