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.

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.”

In late July, Iran’s government announced that it would no longer fund family planning programs, a dramatic reversal following 20 years of support. The change is especially abrupt for a country that has been lauded as a family planning success story, with thorough rural health services and an educated female population contributing to one of the swiftest demographic transitions in history.

“It is plausible that key transitions in human evolutionary history have been driven in large part by climate change,” write Eugene A. Rosa and Thomas Dietz in “Human Drivers of National Greenhouse-Gas Emissions,” a literature review published by Nature Climate Change. “Changes in climate will doubtless be a key force in the future evolution of social systems, including all aspects of social, economic, and political life, while impinging on the health and well-being of the individuals who populate them.” Rosa and Dietz cite numerous studies to argue that nearly every facet of society will be affected by climate change. “The critical point,” they write, “is that population, affluence, technology, and all other drivers act not alone or additively but in a multiplicative fashion.” For example, rapid population growth can lead to an increase in urbanization, which generates “substantial demand for goods and services that can induce emissions in distant places.” They conclude that huge changes must be made in technology and consumption in order to combat the effects of climate change that are being caused by a growing population and an increasingly affluent world.

The National Intelligence Council is trying something new for this year’s Global Trends report: keeping a blog. So far, there have been postings from analysts and contributors on everything from migration and urbanization to international banking and precision strike capabilities, but over the past week, one of the most extensive series yet went up on demography. Though youth bulge theories have often dominated population-related security discussions, 11 posts highlight the newest and least understood of all demographic conditions: advanced population aging.

Urbanization and climate change may be the two most important trends to shape global development in the decades ahead. On the one hand, urban cities have the potential to serve as engines of change, driving economic growth in some of the world’s least developed countries and pulling more people out of poverty than at any other time in history. On the other hand, climate change could undercut all of this by exacerbating resource scarcity and putting vulnerable communities at risk from sea level rise and more frequent and intense storms.

Mongolia, a vast, sparsely populated country almost as large as Western Europe, is at once strikingly poor and strikingly rich. Its GDP per capita falls just below that of war-torn Iraq, and Ulan Bator has some of the worst air pollution ever recorded in a capital city. At the same time, Mongolia sits atop some of the world’s largest mineral reserves, worth trillions of dollars, and its economy, already one of the world’s fastest growing, could expand by a factor of six by the end of the decade as those reserves are developed.

The original version of this article, by Fiona Harvey, appeared in The Guardian.

The global battle for natural resources – from food and water to energy and precious metals – is only beginning, and will intensify to proportions that could mean enormous upheavals for every country, leading academics and business figures told a conference in Oxford on Thursday.