Building height is a crucial variable in the study of urban environments, regional climates, and human-environment interactions. However, high-resolution data on building height, especially at the national scale, are limited. Fortunately, high spatial-temporal resolution earth observations, harnessed using a cloud-based platform, offer an opportunity to fill this gap. We describe an approach to estimate 2020 building height for China at 10 m spatial resolution based on all-weather earth observations (radar, optical, and night light images) using the Random Forest (RF) model. Results show that our building height simulation has a strong correlation with real observations at the national scale (RMSE of 6.1 m, MAE = 5.2 m, R = 0.77). The Combinational Shadow Index (CSI) is the most important contributor (15.1%) to building height simulation. Analysis of the distribution of building morphology reveals significant differences in building volume and average building height at the city scale across China. Macau has the tallest buildings (22.3 m) among Chinese cities, while Shanghai has the largest building volume (298.4 10⁸ m³). The strong correlation between modelled building volume and socio-economic parameters indicates the potential application of building height products. The building height map developed in this study with a resolution of 10 m is open access, provides insights into the 3D morphological characteristics of cities and serves as an important contribution to future urban studies in China.

As of 2023, the bulk of the Chinese population was aged between 25 and 59 years, amounting to around half of the population. A breakdown of the population by broad age groups reveals that around 61.3 percent of the total population was in working age between 16 and 59 years in 2023. Age cohorts below 25 years were considerably smaller, although there was a slight growth trend in recent years. Population development in China Population development in China over the past decades has been strongly influenced by political and economic factors. After a time of high fertility rates during the Maoist regime, China introduced birth-control measures in the 1970s, including the so-called one-child policy. The fertility rate dropped accordingly from around six children per woman in the 1960s to below two at the end of the 20th century. At the same time, life expectancy increased consistently. In the face of a rapidly aging society, the government gradually lifted the one-child policy after 2012, finally arriving at a three-child policy in 2021. However, like in most other developed countries nowadays, people in China are reluctant to have more than one or two children due to high costs of living and education, as well as changed social norms and private values. China’s top-heavy age pyramid The above-mentioned developments are clearly reflected in the Chinese age pyramid. The age cohorts between 30 and 39 years are the last two larger age cohorts. The cohorts between 15 and 24, which now enter childbearing age, are decisively smaller, which will have a negative effect on the number of births in the coming decade. When looking at a gender distribution of the population pyramid, a considerable gender gap among the younger age cohorts becomes visible, leaving even less room for growth in birth figures.

Thanks to the substantial economic development in the country, obesity is replacing malnutrition and growth delay in becoming a new prominent health issue among China's youth. In December 2020, China's National Health Commission reported that while the average height of youngsters between six and 17 years old increased between 2015 and 2020, the obesity rate also rose continuously, with almost one in five children and adolescents aged between six and 17 years being obese or overweight.

In 2022, the average height of South Korean men in their thirties lay at 174.71 centimeters. Men in older age groups tended to be shorter. On average, South Korean men were 171.49 centimeters tall that year.

 Diet and healthcare in South Korea

It has been observed that improvements in nutrition and healthcare lead to increased average height over time. With the rapid industrialization in South Korea came improvements in healthcare and nutritional intake. South Korea ranks among the leading countries in the health index, which measures a population’s health and a country’s healthcare system. Even with an excellent healthcare system, South Koreans have increasingly been concerned about their diet and nutrition, exemplified by the share of people trying to consume certain nutrients every day.

 Height preferences in South Korea 

According to a 2019 survey, for most respondents the preferred height for South Korean men was higher than the current average. This discrepancy was similar for the preferred height for women, showing how preferences for taller people stretched across genders. Not only are South Koreans preferring taller partners, but they are also getting taller over time. Another survey found that the ideal height for a spouse in the country came closer to the average height of younger generations.