Relaxing its restrictions on family size would make it more difficult for China to achieve its goal to be carbon neutral by 2060, according to a new study by UCL researchers.
The paper, published in Nature Climate Change, is the first research to analyse the impact of a country's population policies on its future carbon emissions.
Researchers estimated the carbon footprint of China's projected population under different fertility policies, including its former two-child policy, current three-child policy and a hypothetical "replacement-level" birth rate (of 2.1 children), that would maintain the country's population at its current level of about 1.4 billion indefinitely.
They found that by relaxing its fertility policies and allowing for more children, China's future population and associated carbon footprint will be greater than it would have otherwise been, making it harder to achieve its stated goal of carbon neutrality by 2060.
Lead author, Professor Zhifu Mi (UCL Bartlett School of Sustainable Construction) said: "China is one of the most populous countries and one of the largest carbon emitters in the world. Capturing the impacts of fertility policies on the country's future population and carbon emissions is crucial for its sustainable development."
Originally implemented to limit stress on limited resources in 1979, China's one-child policy largely limited the country's population growth. It also had the effect of making the country demographically older over time as there were fewer young people to offset the aging population. This one-child policy was replaced with a two-child policy in October 2015, and then by its current three-child policy in May 2021, to cope with population aging.
China's fertility rate was 1.3 births per woman in 2020, lower than the "replacement-level" of 2.1 births per woman needed to maintain its population.
This situation has led to an aging population where the proportion of the population over the age of 65 has doubled from 7% in 2000 to 14% in 2020. In addition, China's population declined by 0.85 million in 2022, marking the first population drop in six decades.
The researchers found that even under the current three-child policy, China's population will still contract to about 1.3 billion by 2060 because not all people will start families, and not all families will have the maximum three children. Under the former two-child policy, the population would contract to about 1.15 billion by 2060, while maintain at 1.39 billion if the country reaches replacement level. Using these estimates, the percentage of people over the age of 65 will increase to 42% of the population under the two-child policy, 37% under the three-child policy, and 35% under the replacement-level.
Future estimated population impact on carbon emissions
The researchers analysed the projected carbon footprints from the different projected demographics under the three different population policies through 2060 when China aims to be carbon neutral.
Though collectively China is the world's largest carbon emitter, the amount of carbon produced per capita is lower than that of developed countries. The average person in China annually produces about one sixth as much household carbon footprint as someone from the United States, and about one third as much as someone from the UK or Japan. China's average of about 2.34 tonnes of CO2 per capita is similar to that of Mexico, and about three times that of India.
However, this average is not universal across age demographics or regions in China. On average younger generations produce between 1.21 to 2.93 times more carbon dioxide because they tend to be wealthier, leading to greater consumption. People living in the more industrialised northwestern and eastern provinces likewise tend to produce more carbon dioxide per capita.
Young people have higher household carbon footprints than their elders, caused largely by greater wealth which leads to greater consumption. The researchers found that now that official policy allows for up to three children in China and the younger generations are wealthier than their elders, China is facing a potentially large increase in carbon emissions, reversing a recent trend.
In addition, the paper estimated the impacts of delayed retirement policies on China's future carbon footprint. In September 2024, China announced plans to gradually raise the retirement age over the next 15 years. The researchers found that while raising the retirement age might lead to a slight increase in its carbon footprint, it would considerably reduce dependency ratios and help ease the pressures of an aging population.
Professor Zhifu Mi said: "It is our hope that this better understanding about the future of the carbon footprint of China's population can help to inform policies that encourage young people to live more sustainable lifestyles, such as by reducing consumption, using public transport and purchasing long-lasting goods."
