In today’s world, aging societies and population decline are becoming increasingly prevalent, but in Japan, these challenges have reached unprecedented levels. A staggering 36.21 million people, representing 28.9% of the population, are aged 65 and over.
What’s more, 74.6% of Japan’s 1,747 cities are classified as shrinking, leaving urban policies struggling to keep pace with the decline. Despite these stark realities, the precise factors influencing population changes in cities of different sizes remain unclear.
Dr. Haruka Kato, a junior associate professor at Osaka Metropolitan University, has taken a groundbreaking approach to unraveling this complex issue. Leveraging the Economic, Social, and Educational (ESE) dataset – a comprehensive collection of 270 indicators for each Japanese city – Dr. Kato has employed the cutting-edge machine-learning algorithm XGBoost. This powerful tool has enabled her to uncover the intricate, nonlinear relationships between population changes from 2005 to 2010 and the myriad other factors at play.
The findings highlight the prevalence of medium-sized or small shrinking cities in Japan. Notably, the rate of population change is strongly linked to social factors, such as changes among persons ages 0-14 in small cities, natural population change in medium-sized cities, and migration rates in large cities.
In Japan, the issue of shrinking cities is a pressing concern, with 1304 cities experiencing population decline. These cities, mostly medium-sized and small-sized, are grappling with a range of factors affecting their growth. From economic indicators like the financial strength index in medium-sized cities to urban-planning-related issues such as the designation of underpopulated areas in small-sized cities, the challenges are multifaceted.
This paints a vivid picture of the complex landscape that urban policymakers must navigate. By understanding the unique factors at play in cities of different sizes, policymakers can tailor effective strategies to address the population decline and drive sustainable urban development.
“These results imply that urban policies should be designed according to the size of the city,” said Dr. Kato. “Medium-sized cities should effectively formulate policies other than urban planning, such as childcare initiatives that would contribute to improvements in natural population change and the financial strength index. Meanwhile, small cities need to consider designating underpopulated areas.”
Journal reference:
- Haruka Kato. Multidimensional factors correlated with population changes according to city size in Japan. Environment and Planning B: Urban Analytics and City Science, 2024; DOI: 10.1177/239980832412743