In July of 2018, I made a bold and highly uniformed decision – I decided to travel Japan in the peak of summertime. I had heard rumours of extreme heat and humidity, however looking at weather forecasts it seemed relatively mild. My first destination was Tokyo, a 10 hour flight.
I will never forget exiting customs into the train station of Tokyo airport. Images of western products in a confusing font. The unfamiliarity of a non-English language blaring across the speaker system. And most of all, the extreme humidity. I was dripping in sweat by the time I boarded the train. As it was 10pm at night, I calculated I had been awake for over 18 hours. Fatigue was setting in and I had not reached my hotel. All I had to rely on was Google Maps and the assurance that my phone battery would survive the journey. Try as I might, I couldn’t find anyone that spoke English to guide me. Talk about culture shock!
Luckily I successfully arrived at my hotel in central Tokyo (and thanked my lucky stars). Several days later while on a group tour, we were approached by a Japan weather tv crew. They presented an appropriate question: “How are you surviving the heat wave in Tokyo?”. Mostly via perspiration, I thought to myself. We were informed it was 38 degree Celsius at 10am. That’s warm even by international standards. I looked down at my phone some hours later to check the weather – 34 degrees Celsius and feels like 45 degrees Celsius. How was that possible? Why did it feel 11 degree hotter than what it was? The answer relates to the Urban Heat Island Effect.
When the sun’s rays penetrate to earth there is a reflective by-product created in the form of heat. In highly urbanised environments, there is a high proportion of concrete, roads, and other structures that trap and emit heat. Dark surfaces such as roads absorb significantly more solar radiation. Rather than absorbing and reflecting the heat, these urban environments trap heat, especially during heatwaves and at night. Additionally, humans also produce warmth through body heat, which is amplified in highly urbanised environments like Tokyo. Waste heat from cars, industry, air-conditioning and other sources also contribute to the Urban Heat Island effect.
An interesting phenomenon occurred when I sought refuge in Yoyogi park, Tokyo, the temperature dropped. Or at least it felt like it did. The presence of trees, water, rooftops gardens and other green areas have a protective effect against the urban heat island. They lower the relative heat of a city. More and more cities are starting to wake up to the benefit of greening cities, with the City of Melbourne, Australia taking a lead in this program. It is one strategy to reduce to relative effects of climate change and heat waves, in a warming world.