Over the next two decades, as many as three billion people will join the middle class, even as billions more live without electricity, modern cooking fuel, and safe and reliable access to food and water. Resources are becoming more scarce and more difficult to extract, and combined with environmental factors ranging from climate change to soil erosion, those changes will make meeting middle class demand all the more difficult while leaving the world’s poorest more vulnerable to price shocks and resource shortages. In a recent report, the McKinsey Global Institute concludes that nothing less than a “step change” in how resources are managed will be required if individuals, businesses, and governments are to overcome these trends and pave the way for a more sustainable and equitable future.

The original version of this article appeared on The Economist.

Economies benefit when people start having smaller families. As fertility falls, the share of working-age adults in the population creeps up, laying the foundation for the so-called “demographic dividend.” With fewer children, parents invest more in each child’s education, increasing human capital. People tend to save more for their retirement, so more money is available for investment. And women take paid jobs, boosting the size of the workforce. All this is good for economic growth and household income. A recent National Bureau of Economic Research study estimated that a decrease of Nigeria’s fertility rate by one child per woman would boost GDP per head by 13 percent over 20 years. But not every consequence of lower fertility is peachy. A new study by researchers at the Harvard School of Public Health identifies another and surprising effect: higher inequality in the short term.

The original version of this article, by Christina Larson, appeared on Yale Environment 360.

Bouncing along bad roads in a jeep through central Mongolia, with bright blue skies and high clouds overhead, we drive for miles through a treeless landscape, passing only dry grasslands dotted with cattle and white yurts. But as we head north – myself, two U.S. scientists, and one Mongolian forestry expert – we begin to notice Siberian pine and larch growing on the northern slopes of rolling hills, but not the southern slopes, and at some elevations, but not others. In water-scarce Mongolia, as my travel companion Neil Pederson of Columbia University’s Lamont-Doherty Earth Observatory explained, the precarious growth of trees is limited by temperature and moisture availability; small variations – northern slopes are slightly cooler and wetter – can make all the difference.

In the “first spatially explicit comparison of groundwater use, availability, and environmental flow for aquifers globally,” a new article in Nature finds that the “size of the global groundwater footprint is currently about 3.5 times the actual area of aquifers.” An aquifer’s footprint is the theoretical size it would need to be to sustainably support use at its current rate, so groundwater footprints being much larger than their corresponding aquifers is a sign of overuse.

“I’m going to talk about religion. But it’s a broad and very delicate subject, so I have to limit myself. Therefore I will limit myself to only talk about the links between religion and sexuality…I will talk on what I remember as the most wonderful – it’s the moment when the young couple whispers, ‘tonight, we are going to make a baby,’” said Hans Rosling, the eclectic Swedish doctor and statistician known for his Gapminder tool, in a TedxSummit presentation in April.

Contraceptives prevented an estimated 272,040 maternal deaths in 2008, reducing worldwide maternal mortality by 44 percent, according to a recent paper by Saifuddin Ahmed, Qingfeng Li, Li Liu, and Amy O. Tsui, published in The Lancet. But the prevention of maternal deaths could have been even higher. The study, “Maternal Deaths Averted by Contraceptive Use: An Analysis of 172 Countries,” estimates that an additional 104,000 maternal deaths – many occurring in developing parts of Africa and South Asia – could have been averted simply by satisfying existing unmet need for contraception. In sub-Saharan Africa, for example, only 22 percent of women who are married or sexually active use contraception – a far cry from the 65 percent which the study suggests is the point at which maternal deaths avoided by contraceptive use begin to plateau. Not surprisingly, this has also yielded some of the highest regional fertility rates in the world.

Such high fertility rates are driving growing concerns about scarcity and capacity in the region, and how climate change might exacerbate already-difficult development hurdles. This nexus of issues was the subject of a recent policy brief by Population Action International and the African Institute for Development Policy, titled Population, Climate Change, and Sustainable Development in Africa. The brief points out that “a large share of Africa’s population lives in areas susceptible to climate variation and extreme weather events,” and that there is an inherent tension the continent faces as it seeks to balance high population growth with climate change-induced reductions in the availability of natural resources, like water and arable land.  The authors urge policymakers, rather than focusing on environment, population, and health individually, to “connect population dynamics and climate change” to address their interlinked challenges together.

June’s Rio + 20 Conference on Sustainable Development left environmentalists little to cheer about. Kumi Naidoo, executive director of Greenpeace International, called the meeting “a failure of epic proportions.” And Washington Post reporter Juliet Eilperin said the conference “may produce one lasting legacy: convincing people it’s not worth holding global summits.”