Global Human Population Isn't Going to Explode—But That Doesn't Mean We're Safe | Opinion

Population has grown super-exponentially over the 20th century, which has led to some alarmist messages along the way. The most well known of them is the 1968 book, The Population Bomb, by Stanford professor Paul Ehrilch. Mass starvation due to the classic Malthusian catastrophe of population growth outpacing food production was predicted for the 1970s and 80s in the absence of immediate implementation of population reduction measures. This dire prediction did not materialize, of course, thanks to the Green Revolution.

The main drivers of population growth are death and birth rates—but the initial population size is important as well. Lifespan has lengthened due to medical miracles, while fertility has dropped across the board due to birth controls and family planning. But most importantly, because of the education and empowerment of women.

While population growth rates have declined, total population has continued to grow due to the initial size of the population, referred to as population momentum. The UN Department of Economic and Social Affairs projected in 2017 that Earth's population would surpass 11 billion by 2100, despite these fertility and population growth rate trends.

The UN expects that nearly 70 percent of the world's population for the latter half of the 21st century would be made up of a population with fertility rates below-replacement (less than 2.1 births per woman). And yet, there has been a steady call for population reduction—only now in the context of emission targets developed by the Intergovernmental Panel on Climate Change (IPCC) to meet global warming goals.

This "Population Climate Bomb" alarm is founded on ignoring several important factors that have brought us to this state of affairs as far as climate change is concerned. Foremost is the arbitrary accounting of the impact of population on climate, which neglects the global trade network where emissions are moved around hidden in goods and services.

Even the lowered fertility rates among the educated and empowered women may be associated with an unintended upward bump in per capita consumption (as discussed below). Additional complications arise because humanity has yet to chart a course to increasing the Human Development Index without increasing the environmental footprint. All developed countries have a high environmental footprint and no developing country can achieve higher standards of living without increasing its per capita consumption.

The IPCC has often been accused of ignoring population as a driver of climate change and global warming. Population projections are very much a part of the calculations for future scenarios on emission, mitigation and adaptation—but some would like a more explicit mention of the impact of population reduction on greenhouse gas emissions.

John Bongaarts and Brian O'Neill offer the latest consternation about population being left out in the cold in global warming. They seemingly cover all angles of the argument for including population reduction as an explicit component of the overall IPCC climate assessment. The major missing piece is, of course, that consumption patterns of humans show no hint of slowing down. Both in developed and developing countries.

They identify four major misconceptions about population:

⦁ The misconception that population growth is no longer a problem leads them to point out that birth rates remain high and have not declined over Sub-Saharan Africa.

⦁ They argue that the misconception that population policies are not effective is false by using the example of Bangladesh as a success story in reducing population growth compared to Pakistan.

⦁ They dismiss the misconception that population does not matter much for climate by highlighting that a 40 percent or higher reduction in emissions could be achieved, according to one estimate, with population reduction.

⦁ In discussing the misconception that population policy is too controversial to succeed, they go a step further and argue that population reduction in developing countries not only poses challenges for climate and development but it also 'deprives' the international community of a policy lever to improve human welfare.

A few major realities go missing in this stream of thought. It is absolutely evident that growing population puts enormous burden on natural resources, energy sources, habitats for all other species, and on land use change. Here are the complications that make the population story more intricate than it would appear.

Despite the few exceptions, birthrates across the globe have been declining. The sociopolitical factors that lead to exceptions are important to deal with. However, while the educated and empowered women have fewer children, the main motivation for that is to provide more resources to each child. The impact of this seemingly benign calculation of having fewer children with more resources for each has come home to roost already. Per capita consumptions continue to grow when each child is given more resources or wealth.

Unlike birth rates, per capita consumption shows no decline anywhere on the planet. Even in countries like China and India, where the per capita emissions are half and one eighth, respectively, of those in the U.S., the wealthy denizens of these developing countries tend to have a similar per capita emission to the US. The averages are thus not an indication of lower consumption across the board but just an indication of poverty.

Economic development will necessarily raise per capita emission unless we focus on reduction of consumption as the most important goal for all human activities. Even if the developing world accomplishes miraculously high reductions in populations, the total emissions will not come down unless per capita consumptions are reduced even faster. The calculations that estimate 40 percent reductions in emissions with population reductions do not account for the fact that there are massive loopholes in the way per capita consumptions are currently assigned.

The global economy has allowed developed countries to outsource their emissions by manufacturing goods in developing countries and importing finished goods. It is estimated that up to 25 percent of the global carbon footprint is hidden in imported goods. The attribution of emissions will likely never be fair just as the attribution of population impacts on land use change or forest degradation and deforestation is also unlikely be fair.

Trading of grains, fruits, vegetables, timber, biofuels, etc., is a complicated web across the planet, where a developing country is depleting its water, soil and forests for its economic survival and growth, while a developing country is enhancing its quality of life by importing goods and services and bragging about reducing its emissions and pollution.

None of this diminishes the value of continued humane pathways to birth control and family planning. But unintended consequences must never be ignored. The retraction of the one-child policy in China is a prime example. In the meantime, a piece of good news may be staring at the global community in terms of the age structure of populations in many developing countries.

The developed world has a narrow base of younger population with a nearly even distribution up to the aging population. Japan stands as a stark example of an ever growing aging population due to stagnating birth rates. Developing countries on the other hand display a pyramidal age structure with a large base of population under 25. This offers a golden opportunity to educate and empower girls and young women. Nothing has proven more effective as a contraception than educating and empowering women.

Climate assessments including adaptation and mitigation scenarios by the IPCC are indeed better served by focusing on reducing energy intensity of GDPs and carbon intensity of energy production. Population is a problem that is solving itself. Our penchant for high-energy lifestyle shows no signs of diminishing. Our energies are best focused on evolving into carbon-neutral sapiens who will naturally settle into a healthy population level.

Raghu Murtugudde is a Professor of Atmospheric and Oceanic Science and Earth System Science at the University of Maryland. He is currently a Visiting Professor at the Indian Institute of Technology, Bombay in India. His research focuses On the role of the oceans on climate variability and change including the biological feedbacks on climate.

The views expressed in this article are the author's own.​