The waters of Lake Chad sustain 70 million people in four countries. Beginning in the 1970s, the 25,000-square-kilometer lake began shrinking due to excessive drawdown for agriculture and mining. Now only 10 percent remains. The dwindling water supply devastated food production and fostered massive economic and political tensions. Many experts credit the worsening conditions for contributing to the rise of Boko Haram, an extremist group that has killed 20,000 people and forced 2.3 million more to flee.

Known as the “vitamins of industry,” rare earths refer to a cluster of minerals widely used in green technologies such as wind turbines, rechargeable batteries, and electric vehicles. Rare earth elements embedded in these products keep them light, efficient, and affordable. They’re essential to the decarbonization of the global economy envisioned in the Paris Climate Agreement, agreed to by 192 countries in 2015. And we may soon face a significant shortage, due in no small part to changes in China.

More than 40 years ago, the Soviet Union attempted to harness hydropower to modernize Afghanistan. Between 1960 and 1968, they poured money and technical knowledge into the 100-meter Naghlu gravity dam outside Kabul and a village for its workers called Sharnak. Although the town has been damaged and the boons of modernity remain elusive for many Afghans, the dam remains a crucial source of power for the capital and is the largest power plant in the country with an installed capacity of 100 megawatts.

This week, newly minted Secretary of Defense James Mattis joined a long list of senior U.S. military leaders who have warned about the national security threats of climate change.

The intelligence community’s landmark Global Water Security assessment in 2012, warned of major water-driven challenges to U.S. national security. The combined assessment of several intelligence agencies foresaw many challenges to U.S. policy objectives and national security arising from protracted drought, declining water quality, and more natural disasters in countries important to U.S. interests. The intelligence community further warned of rising social instability, cross-border tensions, and a steady drain of resources away from other development objectives. These warnings have proven prescient.

As the 1990s drew to a close, there was a sense that much of the momentum gained at the first Earth Summit on sustainable development, a positive, affirming environmental narrative, was waning.