Предупреждение ученых человечеству: от 1992 года до наших дней.

1992 document about human carbon footprint
The "World Scientists' Warning to Humanity" was a document written in 1992 by Henry W. Kendall and signed by about 1,700 leading scientists. Twenty five years later, in November 2017, 15,364 scientists signed "World Scientists' Warning to Humanity: A Second Notice" written by William J. Ripple and seven co authors calling for, among other things, human population planning, and drastically diminishing per capita consumption of fossil fuels, meat, and other resources. The second notice has more scientist cosigners and formal supporters than any other journal article ever published.

In late 1992, the late Henry W. Kendall, a former chair of the board of directors of the Union of Concerned Scientists (UCS), wrote the first warning, "World Scientists' Warning to Humanity", which begins: "Human beings and the natural world are on a collision course." A majority of the Nobel Prize laureates in the sciences signed the document; about 1,700 of the world's leading scientists appended their signature. It was sometimes offered in opposition to the Heidelberg Appeal—also signed by numerous scientists and Nobel laureates earlier in 1992—which begins by criticizing "an irrational ideology which is opposed to scientific and industrial progress, and impedes economic and social development." This document was often cited by those who oppose theories relating to climate change. In contrast, the UCS led petition contains specific recommendations: "We must, for example, move away from fossil fuels to more benign, inexhaustible energy sources to cut greenhouse gas emissions and the pollution of our air and water. We must stabilize population."

In November 2017, 15,364 scientists signed "World Scientists' Warning to Humanity: A Second Notice" written by lead author professor of ecology, William J. Ripple of Oregon State University, along with 7 co authors calling for, among other things, limiting population growth, and drastically diminishing per capita consumption of fossil fuels, meat, and other resources. The second notice included 9 time series graphs of key indicators, each correlated to a specific issue mentioned in the original 1992 warning, to show that most environmental issues are continuing to trend in the wrong direction, most with no discernible change in rate. The article included 13 specific steps humanity could take to transition to sustainability. The second notice has more scientist cosigners and formal supporters than any other journal article ever published. The full warning was published in BioScience and it can still be endorsed on the Scientists Warning website.

In October 2022, Eileen Crist, William J. Ripple, Paul R. Ehrlich, William E. Rees, and Christopher Wolf all contributed to the Scientists' warning on population, published by Science of the Total Environment as "part of the ongoing series of scientists' warning publications," to address the negative impacts of population size and growth on the climate and biodiversity, which they posit "continues to be ignored, sidestepped, or denied." It calls for two actions that, if heeded, will stop population growth before the end of this century. Firstly, the authors issue a global appeal to all adults to have no more than one child as part of the transformative changes needed to mitigate both climate change and biodiversity loss. Secondly, the warning urges policy makers to "implement population policies with two key female empowerment components," primarily improving education for young women and girls and providing high quality family planning services to all. It emphasizes that "the combination of institutional support to plan one's child bearing choices and educational attainment, including enhanced opportunity for higher education for women, yields immediate fertility declines." It also posits that a sustainable human population, which according to environmental analysts is "one enjoying a modest, equitable middle class standard of living on a planet retaining its biodiversity and with climate related adversities minimized," is between 2 and 4 billion people. The warning also advocates for combatting poverty, patriarchy and overconsumption by the affluent, and calls for a global wealth tax to be levied primarily against "wealthy nations, industries and people who have benefitted the most from humanity's massive scale historical and contemporary use of fossil fuels" in order to expand "clean sanitation and water availability, food sovereignty, and electrification via renewables." It stresses that poverty alleviation must include the provision of basic public services, in particular healthcare and education.