For those who care about population and sustainability, the meeting was especially disappointing. Despite advocacy efforts by scientists and NGOs from around the world, including a high-profile lead-up report by the UK’s Royal Society, the outcome document failed to recognize the environmental implications of population dynamics and to connect the dots between demography, reproductive health, and sustainable development.

How did this happen? The reasons are many, but here, I’ll focus on one that is fundamental to the global stalemate on environmental issues in general and to population and environment issues in particular: inequality.

The Gap

Around the world, there is a vast – and widening – gulf between the “haves” and the “have-nots.” A 2008 study by the UN University’s World Institute for Development Economics Research found that the richest one percent of adults now own 40 percent of global assets. The bottom half of humanity, in contrast, owns barely one percent of all wealth.

This appalling gap in wealth is matched by disparities in environmental impact: The relatively affluent citizens of industrialized countries consume a far greater share of the planet’s resources and emit a greater quantity of waste than their counterparts in the developing world. According to the Global Footprint Network, if everyone on Earth lived the lifestyle of an average American, we would need five planets to support everyone.

These disparities, and the injustice they represent, are a major obstacle to global consensus and action on environmental problems. Take climate change; because industrialized countries have historically contributed the lion’s share of heat-trapping carbon dioxide emissions, those countries lack the moral authority to call for reductions elsewhere. And developing countries, which are struggling to lift their people from abject poverty, reasonably fear that emissions limits will stunt their development.

Inequality also effectively shuts down discussion of the environmental impact of population growth. It is well established that environmental impact is shaped by a combination of resource use, technology, and population size. The impact of any group of people depends on how they use resources (their systems of production and consumption) and on how many people are doing the producing and consuming.

But, in the context of global inequality, many believe that a focus on population growth is a dodge, a way of shifting attention away from industrialized countries’ supersized consumption habits. As environmental activist and journalist George Monbiot puts it, “population is the issue you blame if you can’t admit to your own impacts: it’s not us consuming, it’s those brown people reproducing.”

All Things Being Equal, Population Matters More

Inequality makes it difficult to address – and even acknowledge – the environmental impact of population growth. But that doesn’t mean that population is irrelevant to sustainability. Indeed, in the more equitable world that many of us would like to inhabit, population dynamics would be more important, not less.

Again, consider climate change. Today, human beings collectively emit more than 30 billion tons of the greenhouse gas carbon dioxide each year. That aggregate figure masks vast disparities in per capita emissions, both between and within countries. Americans are among the highest per-capita emitters on Earth, at about 17 tons per person, per year. Europeans emit about half that and most Indians and sub-Saharan Africans come in at a ton or less. Today, the poorest people in the world make a negligible contribution to climate change.

But let’s imagine a world in which wealth and its attendant environmental impacts are distributed more equitably. Let’s say Americans, through behavior and/or technological change, are able to cut carbon emissions by two-thirds and Europeans cut theirs in half. While we are at it, let’s conjure a massive redistribution of resources and technology, which enables everyone on Earth to converge at an emissions level of five tons per person, per year – about the aggregate level of China today.

Against this backdrop, consider the range of possibilities for future population growth. The UN Population Division predicts that world population will grow from 7 billion today to anywhere between 8 and nearly 11 billion by 2050.

In our equitable world, if world population reaches nine billion (slightly below the UN’s medium variant projection), global carbon dioxide emissions would rise to 45 billion tons of CO₂ per year. This would represent a 50 percent increase over our current level. In the equitable world scenario, the difference between a world population of 8 billion and 11 billion would be about 15 billion tons of CO₂ per year – half our current emissions and quite possibly the margin between a manageable climate crisis and catastrophe.

In the short term, the difference is less dramatic: by 2025, our equitable world would emit 38 billion tons of carbon a year at the low population variant; 42 tons at the high variant. And, of course, it is in the short term that we must drastically reduce our carbon emissions if we are to keep global warming below two degrees Celsius – the threshold set in the Copenhagen Accord to prevent the most disastrous effects of climate change. But there is a clear divergence between the emissions impact of a slow-growing population and a fast-growing one, which widens over time.

In an equitable world, then, population matters. In fact, the only scenario in which population doesn’t matter (much) is one where the current inequitable divide between rich and poor remains fixed for all time. Fortunately, that scenario is unlikely, because development is proceeding, if haltingly, even in the poorest countries.

The Moral Challenge of Our Time

So, what does this mean for the inequitable world in which we actually live?

First, if we take seriously the twin imperatives of social justice and sustainability, we must address inequality by fostering human and economic development in less developed countries. Of course, that will entail greater resource use in these countries. And, since the planet cannot sustain 7 billion people living as we do in the industrialized world – much less a future population of 8 or 11 billion – it is crucial that we simultaneously reduce resource consumption in the industrialized countries and find ways to meet human needs at less environmental cost. One model is the “safe and just space for humanity,” envisioned by Oxfam International, in which all people have the resources they need to fulfill their human rights, while ensuring that humanity’s collective use of natural resources does not exceed sustainable boundaries.

Finally, we should aim for the lower end of the UN population projections. We can do this by educating girls, empowering women, and ensuring universal access to family planning and reproductive health services. These cost-effective interventions not only slow population growth, but, equally if not more important, they have other enormous benefits for women and families. Moreover, by freeing up resources for productive investment, slower population growth can jumpstart development and help reduce inequality. A wealth of evidence suggests that a world population of 8 billion would be better than 11 billion, for human beings and for the natural systems that sustain all life.

Inequality is the moral challenge of our time; it casts a deep shadow over the global debate on sustainability, obscuring other priorities. In fact, the challenges of inequality, overconsumption, and population growth are all vitally important, and profoundly interconnected. All deserve the most urgent priority if we are to build a world that is sustainable and just.

Laurie Mazur is a consultant on population and the environment for the Wilson Center’s Environmental Change and Security Program and a writer and consultant to non-profit organizations. She is the editor, most recently, of A Pivotal Moment: Population, Justice and the Environmental Challenge (Island Press, 2009).

Sources: Encyclopedia of Earth, Futures Group, George Monbiot, Global Footprint Network, International Energy Agency, Oxfam, Population Action International, Rolling Stone, TIME, UN Conference on Sustainable Development, UN Framework Convention on Climate Change, UN Population Division, UN Population Fund, UN University, Washington Post.

I left Rio more hopeful about the future than the official part of Rio+20 would allow. As governments clearly fumbled in the face of the complex challenges of imagining and building a more equitable and sustainable economic growth model in the decades ahead, I saw senior business executives and leaders of civil society engaged in intelligent and productive dialogue about difficult issues at hundreds of thematic panels held at the Corporate Sustainability Forum and other sessions held in Rio.

An initial draft of this conference’s outcome document stated, “We are committed to ensure the equal access of women and girls to education, basic services, economic opportunities, and health care services, including addressing women’s sexual and reproductive health and their reproductive rights.”

In the final draft, the stronger wording “We are committed to ensure the equal access” was switched to the weaker “We are committed to promote equal access.” The reference to reproductive rights was deleted altogether, after opposition from the G-77, a negotiating bloc of developing countries at the United Nations, and the Holy See.

We have the largest youth demographic ever in the history of the world, and most developing nations have a “youth bulge.” This can be seen as a challenge, or opportunity, particularly if the focus is on providing development programs for child survival, family planning, reproductive health, and education. The importance of women’s empowerment was also central. But it’s not a given; it’s an opportunity only if we pay attention to these issues to increase the benefits of the “demographic dividend.”

While I am very pleased that this year’s outcome document endorses sexual and reproductive health and universal access to family planning, to reach our goals in sustainable development we also have to ensure women’s reproductive rights. Women must be empowered to make decisions about whether and when to have children. And the United States will continue to work to ensure that those rights are respected in international agreements.

Now none of this is an abstract discussion. There is just too much at stake, too much still to be done. And many of you visited the U.S. Center here in Rio and saw practical solutions related to some of the work I’ve discussed and other goals we hold in common. We believe solutions require action by all of us. Governments, yes; let’s do our part. Let’s do more than our part.

From the start of the negotiations, gender equality and women’s human rights, including reproductive rights, have continuously been challenged by a few governments, claiming that [these] had “nothing to do with sustainable development.”

This debate continued until the last few hours of the negotiations. In the end, the text includes a re-affirmation of both the Cairo and Beijing agreements, but it falls short by failing to recognize that reproductive rights are also critical to the achievement of sustainable development. If a woman cannot decide if and when to have children and if she is not provided with the reproductive health care that is her human right, it is challenging to contribute to sustainable solutions for the planet.

• Musimbi noted that though the linkages between the environment – particularly climate change – and reproductive health issues can be contentious, we must remember that we are talking about real people with real needs – not abstract ideas.
• Carmen argued that women’s health and rights should be included in the upcoming Sustainable Development Goals, because health is intrinsic to sustainability, and reproductive rights are intrinsic to health.
• Musimbi remarked that climate change, urbanization, energy, and food security are all connected to population, our planet, and reproductive health. She highlighted the need for an open discussion about these linkages, especially for the 200 million women who want access to family planning.
• I pointed out that development projects that address population, health, and environmental issues are making a difference in remote communities around the world.