“We don’t know the reason for the death of fish in downstream villages,” Hamberton Nongtdu, a mine owner from the northeastern Indian state of Meghalaya, told me.

Despite some critics, the recent U.S.-China agreement over carbon emissions has sparked remarkable optimism in global climate negotiations. It’s also opened the door to new bilateral engagement between the U.S. and Chinese environmental communities on other issues, including China’s massive air pollution problems (16 of the world’s 20 most polluted cities are in China).

Imagine an overgrown perennial garden. Impenetrable, shrubby bushes knit themselves together in long rows. Grasses reach chest high. Native hardwood trees hog the perimeter.

The Pangani River in Tanzania is important for many reasons: its three major dams provide 17 percent of the country’s electricity; it sustains thousands of farmers and herders living in the basin; and its flow of fresh water supports humans, industry, and ecosystems. But most interesting might be the innovative water policies that govern withdrawals, infrastructure projects, and ecosystems along its banks.

As is becoming clear, climate change, environmental degradation, population, and poverty alleviation are inextricably linked in many parts of the world. [Video Below]