“The time for talk is done; it is now the time for action,” says Inger Andersen, director general of the International Union for Conservation of Nature (IUCN), in an interview before the 2016 World Conservation Congress.

Times are good for Fey Wei Dong. A genial, middle-aged businessman based in Hangzhou, Fey says he is raking in the equivalent of $225,000 a year from trading in the humblest of commodities: sand.

“There are truly global-scale environmental challenges, and they need to be dealt with by thinking of solutions at the same scale,” said Thomas Lovejoy, a senior fellow at the United Nations Foundation, at the Wilson Center on June 29. The interaction between human population and environmental degradation is one of these challenges. [Video Below]

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.

In the southwestern part of Indonesian Borneo, known as Kalimantan, there’s a small town on the outskirts of an incredibly diverse forest where the community has turned from illegal logging to stewards of the land.

Over the past decade, the number of undernourished people around the world has declined by around 167 million, to just under 800 million people. However, this positive trend glosses over a stark reality: Food insecurity is increasing in the world’s mountains. This pattern has been under-recognized by development experts and governments, a dangerous oversight with far-reaching social and environmental repercussions.

Iraq has seen its share of calamities in recent years, but none is as dangerous as the impending failure of the Mosul Dam. A breach of the dam will result in a tsunami-like wave that sweeps through cities and hamlets along the Tigris River from Mosul to as far south as Amarah and even Basra. Baghdad would be submerged under five meters of water within four days. Not only do experts estimate the possible fatalities to range from 500,000 to more than 1 million, but consider the logistics of trying to provide electricity, drinking water, food, hospitals, transportation, and diesel for millions of people.

Africa has its share of challenges, but it also leads the way in creative development responses. Take the Lake Tanganyika area in Tanzania. Daily life is hard. There are few roads. Cellphone service is patchy. You must travel by boat for seven hours to reach the nearest hospital. And if you have an obstetric emergency, there is no doctor in the village to help you.