Spring is hot and deadly this year
The Hong Kong Observatory has reported that high temperatures in April this year are record-breaking. Concurrently, Southeast Asia also experienced historically high temperatures in April this year due to the strong El Niño phenomenon. Many Southeast Asian cities recorded temperatures exceeding 40 degrees Celsius. Even located at a higher latitude, Japan’s average temperature last April was the highest in nearly 130 years.
The temperature in Hong Kong in April has not always risen significantly in the past. The abnormal temperature increase in April this year may tell us that climate change is precisely changing Hong Kong's seasonal climate.
This year, the weather in Hong Kong continued to be rainy since mid-April, making everyone ignore that this April was about to set a historic abnormal temperature record. Under the joint impact of climate change and El Niño, Hong Kong recorded exceptionally high temperatures in April:
the mean maximum temperature was 28.9 degrees, 3.3 degrees higher than the average value and 1.4 degrees higher than the previous highest value (in 1994);
the mean temperature was 26.4 degrees Celsius, 3.4 degrees higher than the average value and 1.6 degrees higher than the previous highest value (in 1998);
the mean minimum temperature was 24.6 degrees Celsius, 3.5 degrees higher than the average and 1.7 degrees higher than the previous highest value (in 1998).
Moreover, these temperatures on most days throughout the last April were above the average.
If we look into the figures of the top records of April temperature rankings in the past, we will find that the difference between two consecutive rankings is mostly within 0.1 degrees Celsius, and rarely more than 0.5 degrees Celsius.
However, the monthly mean maximum, mean and mean minimum temperatures in April this year are 1.4, 1.6 and 1.6 degrees higher than the previous highest records. The temperatures of April 2024 were unprecedently far higher.
April is usually the hottest month in mainland Southeast Asia such as Vietnam, Thailand and Malaysia. Extreme high temperatures will happen in this month when the intensity of El Niño in previous winter is high. The meteorologists call these Aprils “post-Nino” Aprils and this situation has been worsened by global warming in recent years.
The last time extremely high temperatures occurred in mainland Southeast Asia was in April 2016, and that year there was also a strong El Niño phenomenon that occurred in the previous winter.
However, unlike mainland Southeast Asia, Hong Kong did not use to record unusually high temperatures in April during El Niño years such as 2016. Although Hong Kong did not experience extremely hot weather in April this year, the abnormally high-temperature record may imply that the “post-Nino” Aprils phenomenon is extending from mainland Southeast Asia to southern China, and causing Hong Kong's summer to start earlier.
Hong Kong’s “Post-Nino” April this year also shows that climate change can significantly change the weather of a certain month which will be exacerbated under the influence of climatic cycles such as El Niño.
Hot weather can be deadly. Heat-related death cases increased throughout Southeast Asia countries in this spring season. In Hong Kong, according to the results of a local hot weather-related mortality study conducted by the Chinese University of Hong Kong, when the local average daily temperature exceeds 28.2 degrees Celsius, the mortality rate will increase by 1.8% for every 1-degree increase.
Checking the data of the Hong Kong Observatory, the number of high-temperature days (i.e. the daily mean temperature exceeds 28.2 degrees Celsius) increased from some 70 days to more than 100 days from 2000 to 2023. According to the study, the risk of death related to high-temperature weather in Hong Kong has increased significantly by 1.5 times over the past two decades.
Looking into the future, according to projections by the Hong Kong Observatory based on data from various global climate models of the Intergovernmental Panel on Climate Change (IPCC), Hong Kong's annual mean temperature will range from 24.6 to 27.1 degrees Celsius by the end of this century. Then, the number of deaths triggered by high temperatures will increase by 55 to 554 cases compared with 2022. The situation cannot be ignored.
Environmental Protection Department’s research report on assessing the health and economic impacts of air pollution in Hong Kong set the “Value of Statistical Life (VSL)” at HK$20 million (2022 value). Based on this figure, by the end of this century, the economic loss due to death caused by high-temperature weather in Hong Kong due to climate change will range from HK$1.11 billion to HK$11.08 billion.
We can expect that Hong Kong’s high-temperature weather is likely to extend beyond summer in the future. We have checked the Observatory data and found that from 2000 to 2023, the months with the fastest increase in mean temperature were March, September and November (about an increase of 0.7 degrees Celsius per decade). The months with the fastest temperature increase are in spring and autumn. This means that in the future, the risk of death caused by high-temperature weather will also extend to months other than summer.
Under the aggravating hot weather of Hong Kong, Green Power urges the Government to strengthen urgently the city's ability to adapt to high temperatures and reduce the exposure of citizens to extremely high temperatures, including adding more shaded pedestrian corridors, strengthening community heat shelter services for the needed and reducing the heat sources in our living environment such as exhaust gas from the vehicles. At the same time, public health policies and medical services need to be improved to respond to the increasing risk of death caused by high temperatures. Ultimately the local carbon emission reduction measures must be accelerated to reduce economic and human losses caused by hot weather in the long term.
And now I'd like to dedicate this song for everyone in Hong Kong. "The other side of the sun" by Janis Ian. Thank you and Enjoy!