本研究预计2100年全球总和生育率降至1.6左右，超过75%的国家和地区将无法维持其人口水平。各国过去70年总和生育率均呈显著下降趋势，1950年的4.84降低至1980年的3.61再进一步下降到2021年的2.23。
Title: The Population Situation in the 21st Century
In an era characterized by rapid technological advancements, global population growth has been consistently declining over the past few decades. This trend is particularly notable in countries with an increasing birth rate and demographic shifts. According to your research, it is expected that global total birth rates will decrease to approximately 1.6 by the year 2100, and the proportion of nations unable to sustain their current population levels will be upwards of 75%.
This demographic shift can be attributed to various factors such as declining fertility rates, aging populations, increased life expectancy, and changes in societal norms and attitudes towards family planning. The decrease in fertility rates is likely due to both traditional and modern methods of contraception, which have evolved to become more effective and affordable over time.
Historically, the United Nations Data Centre for Human Development estimates that world population growth has slowed down significantly from the late 20th century, and continues to do so in many parts of the globe. In fact, it is projected that around 75% of countries in the world will be unable to maintain their current population levels by 2100.
The decline in birth rates has led to increased awareness of population-related issues and concerns about sustainability. Governments worldwide have taken steps to promote family planning and reproductive health, investing heavily in infrastructure development, education, and healthcare services.
However, despite these efforts, the challenges faced by nations in maintaining their populations are immense. These include demographic老化, lower birth rates, low fertility expectations, and increased dependence on external factors like economic stability and political stability.
Furthermore, addressing this issue requires significant policy changes at all levels, from individual households to national governments. These policies may involve greater emphasis on contraception, investment in child care facilities, improved access to education and job opportunities, and investments in infrastructure that support families.
It is important to note that while declining birth rates may lead to reduced population growth, it does not necessarily mean a decrease in overall life expectancy. With advances in medicine and other areas, life expectancy is increasing worldwide, and the trend is expected to continue.
In conclusion, while declining birth rates are undoubtedly a concern for policymakers, they should also recognize that they provide an opportunity to address some of the most pressing social and environmental challenges facing our planet. By taking proactive measures to promote family planning and reduce unintended pregnancies, we can help ensure a sustainable future for generations to come.