The impacts of overpopulation on the environment amount to some of the most contested of the many issues relating to climate change, not least due to the various and sometimes coercive ways that governments worldwide have attempted to alter their countries’ population growth.

Although studies have shown that human activity directly contributes to global warming, many methods of population control have raised debate and questions about their effectiveness.

Scientists do agree on one thing: without drastic intervention or a sudden drop in fertility rates, the global population will most likely continue the trend of overall growth that the planet has seen since the beginning of human life.

According to a 2015 report by the United Nations Department of Economic and Social Affairs, humanity will number at least 8.5 billion by 2030, 9.7 billion by 2050 and 11.2 billion by 2100. The study also predicted that the number of people aged 60 or above is expected to more than double by 2050 and to more than triple by 2100 if life expectancy continues its trend of rising in the future.

Those in favor of strict population restriction argue that a reduction in the number of residents in densely populated areas, especially crowded cities, is necessary to prevent the detriments to climate and health caused by overcrowding.

“Each individual person has a carbon footprint,” said Green Team advisor and biology teacher Dr. Katherine Schafer. “Even in the developing world, whether it’s burning charcoal or burning wood or burning coal, in most cases, if you’re trying to get fuel for cooking or for heating or whatever it might be, most of those sources of fuel are not carbon-neutral.”

These scientists argue that because an increase in human numbers would contribute to a hastened depletion of natural resources due to the greater number of people to supply, nations worldwide should implement population control measures immediately. They also assert that per-capita statistics that seem to show progress in mitigating climate change misleadingly ignore this growth in population.

“I think it’s fairly straightforward logic that with more persons, you face a greater challenge in terms of impact on climate and other environmental concerns, whether it’s water or land or food challenges,” said Dr. John Casterline, director of the Ohio State University Institute for Population Research.

Others contend that although population control may be necessary, coercive measures are inhumane and disrespectful of personal privacy. These scientists cite studies showing that a potential global one-child policy would have an equally minimal impact on climate models to more indirect and humane methods of population control, such as increasing access to contraceptives and gynecologic healthcare.

“We know that in the developing world, as conditions improve, reproductive rates tend to go down, and we’ve seen this throughout the world as countries develop,” Dr. Schafer said. ”A strategy for speeding that along is to invest in organizations that are helping to develop those countries by providing medical care, by providing access to education, especially to women, and so forth. All of those things have been shown to slow population growth.”

An example of a governmentally enforced population control measure is China’s one-child policy was introduced in 1979 and was not relaxed until 2015. Scientists skeptical of coercive reproductive control argue that the policy did little on its own to curb fertility rates, which were already decreasing, and that government-enforced population control measures have better alternatives.

“A high fraction of women or couples want to have fewer than five or four children,” Dr. Casterline said. “Enabling people to have what they want, fertility-wise, would lead to a lot of fertility reduction but might not bring it down to as far as we need in terms of climate change and stabilizing world population. You could encourage people to make certain choices and show them it’s to their benefit and to the society’s benefit without making it coercive.”