HK Set for Worst of It Amid Climate Change (只提供英文版本)

By Im Eun Soon, Assistant Professor of Civil and Environmental Engineering and Division of Environment and Sustainability, HKUST


This month, we experienced the hottest day of the year as temperatures in Hong Kong reached 35.1 degrees Celsius.

Countries across western Europe also struggled in record-breaking temperatures recently, with France hit the worst at 45.9 degrees in June.

The grim situation appears to have been a repeat of last year's conditions.

Although there are ongoing indepth analyses and further studies to examine the causes of individual extreme temperature events, many experts believe that extreme heat waves would not be feasible without anthropogenic climate change, meaning human activities are the main culprit for global warming ravages.

Such an assumption has been proven by climate models - a complex computer simulation of physical processes and mathematical formulae used mainly to predict climate and understand how the climate system responds to elevated greenhouse gas emissions.

These models provide robust projections that indicate the length, frequency and intensity of heat waves will increase over most land areas.

Once considered uncommon, heat waves could become the new norm if average global temperatures keep rising.

More specifically, simulations using state-of-the-art climate models forecast that the unprecedented extreme summer Korea experienced in 2018 could emerge annually should we not keep global temperature rises well below the two degrees above pre-industrial revolution levels stipulated in the Paris Agreement, a treaty that for the first time brought all nations into a common cause to undertake ambitious efforts to combat climate change.

Hongkongers will also suffer from the continually rising temperatures: the already humid and hot climate will amplify because even a modest warming may exceed critical levels of heat stress.

Our body has a thermal limit. When the wet-bulb temperature - used as the indicator of heat comfort - hits 35 degrees, the human body loses the ability to cool itself down by sweating and will die in a matter of hours.

Therefore, a place with a wet-bulb temperature that is already high enough to present very uncomfortable conditions with present climate conditions like Hong Kong will face a serious problem if two or three degrees of warming is expected in the future.

Moreover, the effects of urbanization will intensify the risk level of extreme heat for exposure to poor living conditions, such as in subdivided flats in our city.

Climate change was once an abstract concept, but the recent heat extremes may serve as a lesson to enhance public awareness of the potential drastic impact of climate change, as extreme conditions have caused considerable casualties and damage worldwide.

Without public support and engagement, it will not be possible to translate and implement scientific findings to general practice and policy.

While it is important to develop countermeasures to minimize damage from expected climate extremes through coordinated adaptation efforts, all nations should also take an immediate action to mitigate climate change by significantly cutting greenhouse gas emissions from a global perspective.

Pursuing the nationally-stated mitigation ambitions as ratified under the Paris Agreement may make it possible to follow the global greenhouse gas emission pathways that help prevent catastrophic consequences.

For instance, changing from a high dependency on fossil fuels to a timely diversification of renewable energy sector is required.

The article was published on The Standard on Aug 21, 2019.