Abstract: Ironically, the earth may be somehow sustainable today because of conflict, poverty and hunger.
The sustainable population is probably between 2 and 4 billion people [1]. Together we would like to consider a peaceful transition to a prosperous and sustainable population for all, without resorting to unethical means.

If the sustainable world population is the most recent estimates of 2 to 4 billion people (according to Paul R. Ehrlich, the optimal population is 1.5 to 2 billion),[1][2] the human population of approximately 8 billion people (as of 2022) would have to undergo very difficult but peaceful population control. However, extreme measures such as killing each other, spreading disease, and starvation are ethically unacceptable. We must work toward peaceful adjustments to a sustainable population that does not compromise the happiness of all.

One concern is diseases such as AIDS, for which there are conspiracy theories full of doubt that it is used to reduce the population, but which are not known to be true. What is important is that using disease to reduce population is morally wrong. We should fight disease through medical care and raising awareness to achieve sustainable population control while protecting people's health.

It's possible that the current global issues of poverty, hunger, and conflict are related to the concept of sustainable population. This suggests that someone or something may have concluded that the global consumption of resources and environmental impacts necessary for people now and in the future to enjoy a prosperous life, similar to the lifestyle of Americans, may be unsustainable on a global scale. This notion could contribute to keeping certain regions in states of poverty, hunger, and conflict. While this idea is circumstantial, if poverty, hunger, and conflict were successfully resolved at current population levels, and if everyone were to adopt the same resource use and environmental impact as Americans, it could potentially strain the planet's resources [3].

It is possible that one of the main purposes of past wars was to reduce population, but wars cause deep wounds in people. We should try to avoid war and regulate population by peaceful means.

Under the leadership of international organizations, including the United Nations, global campaigns must be launched to strengthen efforts to achieve a sustainable population. Considerable efforts will be required given the results of an estimate that "even if the one-child policy were to begin in 2010, it would take 140 years to reduce the population to 2 billion."[4] It is important to create an environment in which people can voluntarily consider the appropriate number of children through a combination of policy-driven guidance and awareness-raising activities. Particularly in overpopulated areas, it may be necessary to introduce policies such as a "reverse child allowance" to promote sustainable population adjustment. ("Reverse child allowance" is a benefit that should be paid in inverse proportion to the number of children).

People should have a strong will to achieve a peaceful and sustainable population, and we must continue our efforts to realize a society where people live happily together, a world where everyone is prosperous. It is a realistic challenge, and I would like to ask you to think and work together to build a sustainable future through both raising awareness and policy efforts.

[1] Wikipedia [Sustainable Population]
[2] Gretchen C. Daily, Anne H Ehrlich, and Paul R Ehrlich. Optimum Human Population Size. Archived 2017-8-17 at the Wayback Machine...Population and Environment: A Journal of Interdisciplinary Studies Volume 15, Number 6 July 1994 01944 Human Sciences Press Inc.
[3]Glenn Carle. "[Population explosion rather than population decline, what will happen when the population reaches 10 billion in 2055]". Newsweek Japan. 2018-07-03. https://www.newsweekjapan.jp/glenn/2018/07/2055100.php, (last accessed 2023-8-16).
[4] Corey J. A. Bradshaw, Barry W. Brook. Human population reduction is not a quick fix for environmental problems. Proc Natl Acad Sci U S A. 2014. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4246304/, (accessed 2023-7-26).