Changing population
International Baccalaureate · IB Diploma · Geography · SL Topic 1 6:48 English narration · English + 中文 subtitles burned in
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In 2024, nine point five four million babies were born in China and ten point nine three million people died. The population fell for the third year in a row.
2024 年，中国出生 954 万人，死亡 1093 万人，人口连续第三年下降。
Fifty years earlier the problem was the opposite: too many births.
五十年前的问题恰恰相反：出生太多。
This topic explains such a change, and what governments can do.
本课解释这种变化，以及政府能做些什么。
Population distribution depends on physical factors, such as climate, water and relief, and human factors, such as jobs and transport.
人口分布取决于自然因素，如气候、水源和地形，以及人文因素，如就业和交通。
In China, about ninety-four per cent of people live east of the Hu Line, on about forty-three per cent of the land.
在中国，约 94% 的人口居住在胡焕庸线以东，只占约 43% 的国土。
The west is high, dry and cold.
西部高、干、冷。
Population density is people divided by area.
人口密度是人口除以面积。
Take a desert country with ten million people on a million square kilometres: ten people per square kilometre.
设想一个沙漠国家，一千万人、一百万平方千米：每平方千米十人。
But divide by its twenty thousand square kilometres of farmland and the physiological density is five hundred.
但若只除以两万平方千米的耕地，生理密度就是五百人。
That shows the pressure on the land that grows food.
它反映了产粮土地承受的压力。
People also move towards cities.
人们也向城市迁移。
A megacity has more than ten million people; there were thirty-three in 2018.
超大城市人口超过一千万，2018 年有 33 个。
Inside a country, a rich, well-connected core region, such as the Yangtze River Delta, draws people, money and ideas from a poorer periphery.
在一个国家内部，富裕、交通便利的核心区，如长三角，从较贫穷的边缘区吸引人口、资金和思想。
Four measures.
四个指标。
The crude birth rate is births per thousand people a year, and the crude death rate is deaths per thousand.
粗出生率是每年每千人的出生数，粗死亡率是每年每千人的死亡数。
Natural increase is one minus the other.
自然增长率是两者之差。
The total fertility rate is the average number of children a woman has.
总和生育率是每名妇女平均生育的子女数。
About two point one is replacement level; China's is about one, and Niger's about six.
约 2.1 是更替水平；中国约为 1，尼日尔约为 6。
A country has a birth rate of twenty-four and a death rate of eight per thousand.
某国出生率为千分之二十四，死亡率为千分之八。
Natural increase is sixteen per thousand: one point six per cent a year.
自然增长率是千分之十六，即每年 1.6%。
Doubling time is about seventy divided by the growth rate, so seventy over one point six: about forty-four years.
倍增时间约等于 70 除以增长率，70 除以 1.6，大约 44 年。
Total change also adds net migration.
总人口变化还要加上净迁移。
Read the graph.
读图。
In 2016 China had seventeen point eight six million births.
2016 年中国出生 1786 万人。
Births fell almost every year, while deaths slowly rose.
此后出生人数几乎逐年下降，死亡人数缓慢上升。
The lines crossed in 2022, and natural decrease began.
两条线在 2022 年相交，开始出现人口自然减少。
In 2024, natural change was minus one point three nine million.
2024 年自然变化为负 139 万。
The demographic transition model shows birth and death rates as a country develops.
人口转变模型展示国家发展过程中出生率和死亡率的变化。
In stage one both are high.
第一阶段两者都高。
In stage two death rates fall fast with clean water and vaccines, so growth is very fast.
第二阶段由于清洁水和疫苗，死亡率迅速下降，人口增长很快。
In stage three birth rates fall too.
第三阶段出生率也下降。
In stage four both are low.
第四阶段两者都低。
In stage five births fall below deaths, as in Japan and China.
第五阶段出生率低于死亡率，如日本和中国。
The model is based on European history.
这个模型基于欧洲历史。
It leaves out migration, and it does not say how long each stage lasts.
它不包括迁移，也不说明每个阶段持续多久。
China passed through stages two to four in about fifty years, much faster than Britain.
中国用大约五十年走完第二到第四阶段，比英国快得多。
A population pyramid shows the number of people in each age group.
人口金字塔显示各年龄组的人数。
A wide base means many young people. Straight sides mean similar numbers at each age. A narrow base means few recent births.
底部宽表示年轻人多；两侧直表示各年龄人数相近；底部窄表示近年出生少。
The dependency ratio compares people of non-working age with people of working age.
抚养比是非劳动年龄人口与劳动年龄人口之比。
A town has twenty thousand children and fifteen thousand people over sixty-five: thirty-five thousand dependants.
某镇有两万名儿童和一万五千名六十五岁以上老人，共三万五千名被抚养者。
Divide by seventy thousand of working age and multiply by a hundred: fifty.
除以七万劳动年龄人口再乘以一百，得五十。
Every hundred workers support fifty dependants.
每一百个劳动者抚养五十人。
When birth rates fall, a country has for some years many people of working age and few dependants. This can speed up growth: the demographic dividend.
出生率下降后，一个国家在若干年里劳动年龄人口多、被抚养人口少，这能加快经济增长，即人口红利。
China's fast growth from the 1980s used it.
中国自 1980 年代以来的快速增长就利用了它。
Now those workers are ageing, and the dividend is ending.
如今这些劳动者正在老去，红利正在消失。
An ageing population, like Japan's with twenty-nine per cent over sixty-five, has fewer workers and spends more on pensions and health care.
老龄化人口，比如日本 29% 的人超过六十五岁，劳动者更少，养老金和医疗支出更多。
But older people care for grandchildren and volunteer, and silver industries grow.
但老人照顾孙辈、做志愿者，“银发”产业也在发展。
A youthful population needs schools and jobs; without jobs, young people may migrate or become frustrated.
年轻型人口需要学校和工作；没有工作，年轻人可能外迁或心生不满。
Governments respond with policies.
政府用政策来应对。
An anti-natalist policy aims for fewer births, like China's one-child policy from 1980 to 2015.
限制生育政策旨在减少出生，如中国 1980 至 2015 年的独生子女政策。
A pro-natalist policy aims for more, like China's two-child and three-child policies, or France's family payments.
鼓励生育政策旨在增加出生，如中国的二孩和三孩政策，或法国的家庭补贴。
And an ageing policy supports older people: China began slowly raising the retirement age in 2025.
老龄化政策则支持老年人：中国 2025 年开始逐步提高退休年龄。
Policies on births work slowly.
生育政策见效很慢。
China allowed three children in 2021, but births kept falling, because housing, education and childcare are expensive and many young people marry later.
中国 2021 年允许生三孩，但出生人数仍在下降，因为住房、教育和托育成本高，许多年轻人结婚更晚。
The sex ratio at birth was also unbalanced: about one hundred and eleven boys per hundred girls, against a natural level of about one hundred and five.
出生性别比也不平衡：约每一百个女孩对应一百一十一个男孩，而自然水平约为一百零五。
Migration is a long-term move from one place to another.
迁移是从一地到另一地的长期移动。
Push factors such as conflict and poverty drive people away. Pull factors such as safety and jobs attract them. Intervening obstacles, such as cost, distance and borders, stop some people on the way.
冲突、贫困等推力因素把人推走；安全、工作等拉力因素吸引他们；成本、距离和边境等中间障碍让一部分人半途而止。
There were about two hundred and eighty million international migrants in 2020.
2020 年全球约有 2.8 亿国际移民。
A refugee has crossed a border to escape persecution or war.
难民是为躲避迫害或战争而越过国界的人。
An internally displaced person has fled too, but stayed inside their own country.
国内流离失所者同样被迫逃离，但仍留在本国境内。
China has one of the largest internal migrations in history.
中国有史上规模最大的国内迁移之一。
The 2020 census counted about three hundred and seventy-six million people living outside the area where their household is registered, most of them from villages to eastern cities.
2020 年人口普查显示，约 3.76 亿人居住在户籍地以外，大多从农村迁往东部城市。
Under the hukou system, many could not easily use schools and health care in their new city.
在户口制度下，许多人难以在新城市使用学校和医疗服务。
Migration affects both places.
迁移对两地都有影响。
The place of origin gains remittances, money sent home, and has less unemployment, but it loses young workers, and children stay behind with grandparents.
迁出地获得侨汇，即寄回家的钱，失业也减少，但会失去年轻劳动力，孩子留给祖父母照看。
The destination gains workers and a younger population, but faces pressure on housing and services, and sometimes tension with local people.
迁入地获得劳动力和更年轻的人口，但住房和公共服务承受压力，有时还会与本地居民产生摩擦。
To finish: distribution and the two densities; natural increase and doubling time; the transition model, pyramids and the dependency ratio; ageing and youthful populations with their policies; and migration, with its push, pull, obstacles and effects.
总结：人口分布与两种密度；自然增长与倍增时间；人口转变模型、人口金字塔与抚养比；老龄化与年轻型人口及相应政策；以及迁移的推力、拉力、障碍和影响。