Population, reproductive health, and environmental sustainability are inextricably linked. Growing populations place increasing demands on the environment, while meeting the reproductive health needs of populations usually slows their growth. Often, however, policymakers, scholars, and journalists discuss these issues separately, as if unrelated.

Global Population and Reproductive Health connects these dots, so to speak, showing that the links between population dynamics, reproductive health, and the environment demand integrated policies and international cooperation.

World population is projected to reach 8 billion by 2024 and at least 10 billion by the end of this century. Yet hundreds of millions of women who want to use modern contraception can’t access family planning services. These facts relate directly to environmental degradation, maternal and child health, the status of women in society, unsafe abortion, contraceptive practice, climate change, food security, and migration.

The increasing human population and its growing resource demands are severely taxing Earth’s carrying capacity. The absolute increase in numbers, along with an expanding world economy, has profoundly altered the connection between people and their environment with alarming repercussions. Population growth and the consumption patterns of rich countries are relentless in degrading ecosystems, including fresh water resources, oceans, wetlands, forests, fisheries, biodiversity, the atmosphere, and even the climate.

Environmental depletion is as old as human civilization, but the current scale and velocity of natural degradation is unprecedented.

Linking global population, reproductive health, and environmental sustainability is the underlying theme of this five-part, 14-chapter edited book. Ten scholars contribute their expertise to a volume intended as a comprehensive primer for a general audience or as a text for graduate students or advanced undergraduates.

Climate Change

Increased greenhouse emissions, produced by human activity, are causing climate change. The major components of human activity driving greenhouse emissions are economic growth, changes in energy and land use, and population growth, writes Karen Hardee in her chapter.

Population size alone is an important driver of greenhouse emissions, but there is uncertainty about the exact size of future populations. Accordingly, the United Nations offers three different projections for human population growth: low, medium, and high. If world population growth follows the low rather than medium growth path, projected global emissions will be reduced by 15 percent in 2050 and 40 percent by 2100.

In addition to size, other aspects of population dynamics affect greenhouse gas emissions. Urbanization, migration, age structure, density, and growth are significant factors because they influence resource use and consumption rates. Each is linked to health, the environment, and the economy, and each affects individual countries’ capacities to adapt to climate change.

Adaptation efforts need to be tailored to global demographic dynamics. Industrialized countries, which have demonstrated high past and present consumption rates, have certainly made the greatest contributions to climate change to date. Grouped together, the populations of more developed countries have largely stopped growing.

In the developing world, despite much lower per capita consumption, ongoing rapid population growth often exacerbates local scarcity of food and water, vulnerability to natural disasters and infectious diseases, and population displacement, all of which are linked to climate change.

Reproductive health services, namely family planning, offer an important strategy for climate change mitigation – that is, reducing or preventing emission of greenhouse gases. Providing women with access to modern contraception so they are able to have the number of children they desire is cost competitive with other mitigation options, such as low carbon energy and forestry and agricultural interventions. Educating girls, which tends to lower fertility aspirations, is also a cost-effective mitigation and adaptation strategy.

Linking reproductive health and population to climate change strategies remains a challenge, however. Most climate change policies neglect mention of population dynamics, despite the fact that population and development policies are increasingly acknowledging the importance of climate change.

Support is mounting for innovative development strategies, such as population, health, and environment (PHE) programs, but not at a rapid enough pace or a large enough scale. By addressing the connections between people, their health, and their environment, PHE offers a promising approach to climate change adaptation in the Philippines, Ethiopia, Nepal, Tanzania, and other countries.

Food Security

Nearly 1 billion of today’s more than 7 billion people have inadequate nutrition. And while food production is still increasing, it is far from clear that it can grow by the 60 percent or so required to meet the projected needs of 9 billion people in 2050, writes Richard E. White in his chapter.

Food security exists when all people at all times have access to sufficient, safe, nutritious food in order to maintain a healthy and active life. There are multiple obstacles to doing this for the entire world: less arable land per person, more demand for meat products with the corresponding diversion of grain supplies to animals, converting food crops to biofuel production, topsoil loss, water scarcity (due to multiple factors, including declining aquafers and climate change), and the finite supply of fossil fuels, needed especially for industrial agriculture.

There are vast regional differences in food security. While not completely exempt from this concern, developed countries face far less acute food insecurity than developing nations. Of the 26 nations listed as the world’s hungriest countries, only Haiti (#6) does not lie in Africa or Asia. Sub-Saharan Africa, ground zero for food insecurity, has low agricultural yields compared to other developing regions as well as the highest human fertility levels and population growth rates.

Population and nutrition are intertwined. In the big picture, growing food security tends to feed population growth, particularly during a period called the demographic transition, as high mortality and fertility rates – the norm for much of human history – give way to low mortality rates and eventually low fertility rates. Improved nutrition contributes to an excess of births over deaths during the transition, which results in rapid growth. Excessive population growth during the demographic transition may trap countries in poverty, thereby worsening food insecurity. Globally, long-term stability of food security requires the cessation of population growth.

Gender norms and mores influence global food security too. In many parts of the world, women play a critical role in smallholder farming. In Africa and the Middle East, women constitute 20 to 50 percent of the agricultural workforce; in some countries, women’s share of the workforce exceeds 60 percent.

Given equal resources, women farmers are as productive as their male counterparts. However, traditional gender roles greatly limit their access to land, technology, education, and capital. Consequently, women farmers typically produce 20 to 30 percent lower yields per hectare. Bringing up the yields on the limited land farmed by women to the levels achieved by men would increase food production in developing countries by 2.5 to 4 percent alone, thereby reducing the number of undernourished people globally by 100-150 million.

Educating and empowering women, particularly with reproductive health services, holds promise for stabilizing global population growth. Such an achievement would moderate the food security challenge as well as the environmental impacts of population growth.

Toward the Future

Constructively and ethically addressing the links between global population, reproductive health, and environmental sustainability requires collective action, a daunting task, given the current climate of reproductive health politics and economic insecurity. Even so, there is too much at stake to shy away from this challenge.

The links discussed above demand cooperation on many levels. At the global, national, and local levels, separate policy communities (sometimes called “policy silos”) address environmental sustainability, population and reproductive health, food security, gender, and climate change. Indeed, in recent years, the United Nations has hosted separate forums for each of these areas. But the design and implementation of effective policies demands more collaboration.

Good policy design must also incorporate valid causal mechanisms of how objectives are to be met. Fortunately, the most effective policy interventions for reducing population growth – extending contraceptive access and educating girls – also improve reproductive health.

Resources and leadership are also required. At the London Family Planning Summit in 2012, both wealthy and poorer nations along with private donors pledged new support for family planning services, an effort that is continuing through the Family Planning 2020 initiative. Unlike the country-specific fiscal commitments made at the 1994 International Conference on Population and Development, these pledges need to be honored, expanded, and updated.

As the world’s largest economy and the original stronghold of international population assistance, the United States should resume a leadership role, including, but not restricted to, greater fiscal contributions.

Progress toward meeting global objectives must be measured at regular intervals. Policymaking, policy implementation, and policy evaluation take place in real time with ongoing needs and unexpected crises. At any time, there are competing demands for the attention of policymakers and the public. Solid evidence and ongoing research strengthen arguments for more support. It is no exaggeration to say that the world’s future depends on how global population, reproductive health, and environmental sustainability are addressed in our time.