According to a new study published in the Lancet journal, the world population will decline for the first time in the next century.

发表在《柳叶刀》杂志上的一项新研究称，下个世纪全球人口将首次下降。

The world's population is currently estimated to be at 7.8 billion people.
目前，全球人口预计为78亿。

According to the estimate, the global population would peak at around 9.7 billion in 2064.
据估计，全球人口将在2064年达到峰值，约为97亿。

Then it will fall to 8.79 billion in 2100.
然后在2100年下降到87.9亿。

Due to low birth rates and aging populations, up to 23 countries, including Japan, Thailand, Italy, Spain, Portugal, South Korea, and others, might see their populations fall by more than 50%.
由于低出生率和人口老龄化，包括日本、泰国、意大利、西班牙、葡萄牙、韩国等在内的多达23个国家的人口可能会下降50%以上。

China is the world's most populated country. But it will see its population drop from 1.4 billion in 2017 to 732 million in 2100.
中国是目前世界上人口最多的国家，但到2100年，中国的人口将从2017年的14亿下降到7.32亿。